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1.  Dynamics of Constructs in Successful Aging of Korean Elderly: Modified Rowe and Kahn’s Model 
Objectives
This study examined components in Rowe and Kahn’s successful aging model to investigate their hierarchical order and led to a modification of the previous hierarchical order.
Methods
To examine the hierarchical order of components, we constructed a structural equation model and verified those paths that have discrepancies in studies and/or potential inclusion or omission errors in the model. For this purpose, we analyzed 556 cases out of stratified and purposively sampled 600 elderly people living in the city of Jeonju during the study period (2011).
Results
The paths with inclusion errors such as H3 [self-reported health → productive activity (SRH → PA)]: the effect of SRH on PA, and H6 [social network (SN) → PA]: the effect of SN on PA, were not directly but indirectly supported. The path with discrepancy, H4 [SN → physical–cognitive function (PCF)]: the effect of SN on PCFs, was statistically significant. The path with inclusion error and discrepancy, H8 (PCF → PA): the effect of PCF on PA, was not directly but indirectly supported. Also the path with the omission error, H2 [SRH → psychological trait (PT)]: the effect of SRH on PT, was statistically significant. The other paths in the hierarchical order of the model reported in previous studies were statistically significant.
Conclusion
We verified new dynamics of constructs involved in successful aging, which would provide better understanding of Rowe and Kahn’s successful aging model for Korean elderly people living in a medium-sized city.
doi:10.1016/j.phrp.2012.07.003
PMCID: PMC3738711  PMID: 24159505
productive activity; physical–cognitive function; psychological trait; social network; self-reported health
2.  Prevalence of Successful Aging in the Elderly in Western Mexico 
Objectives. The aim of this paper is to estimate the prevalence of successful aging in the elderly in Western Mexico and to analyze its variability by age, sex, education, marital status, and pension. Methods. This study employs data from the Health, Wellbeing, and Aging Study (SABE) in Jalisco and Colima, Mexico. Successful aging was operationalized in accordance with no important disease, no disability, physical functioning, cognitive functioning, and being actively. There were a total of 3116 elderly. Results. 12.6% of older adults were “successful” aging. The old-old is a lower proportion of successful aging people; it ranges from 18.9% among people aged 60–69 years to 3.9% in the 80–89 years and up to 1% in people 90 and older. There were also differences according to sex (P = .000), with a higher proportion of successful aging men (18.4% compared with 9.2% of women). There were differences in educational level (P = .000); those higher with education were found to be more successful aging, and also there were differences in marital status for married people (P = .000). Discussion. A small number of older adults meet the criteria definition of successful aging, suggesting the need to analyze in depth the concept and the indicators.
doi:10.1155/2012/460249
PMCID: PMC3463158  PMID: 23049550
3.  Recent trends in chronic disease, impairment and disability among older adults in the United States 
BMC Geriatrics  2011;11:47.
Background
To examine concurrent prevalence trends of chronic disease, impairment and disability among older adults.
Methods
We analyzed the 1998, 2004 and 2008 waves of the Health and Retirement Study, a nationally representative survey of older adults in the United States, and included 31,568 community dwelling adults aged 65 and over. Measurements include: prevalence of chronic diseases including hypertension, heart disease, stroke, diabetes, cancer, chronic lung disease and arthritis; prevalence of impairments, including impairments of cognition, vision, hearing, mobility, and urinary incontinence; prevalence of disability, including activities of daily living (ADLs) and instrumental activities of daily living (IADLs).
Results
The proportion of older adults reporting no chronic disease decreased from 13.1% (95% Confidence Interval [CI], 12.4%-13.8%) in 1998 to 7.8% (95% CI, 7.2%-8.4%) in 2008, whereas the proportion reporting 1 or more chronic diseases increased from 86.9% (95% CI, 86.2%-89.6%) in 1998 to 92.2% (95% CI, 91.6%-92.8%) in 2008. In addition, the proportion reporting 4 or more diseases increased from 11.7% (95% CI, 11.0%-12.4%) in 1998 to 17.4% (95% CI, 16.6%-18.2%) in 2008. The proportion of older adults reporting no impairments was 47.3% (95% CI, 46.3%-48.4%) in 1998 and 44.4% (95% CI, 43.3%-45.5%) in 2008, whereas the proportion of respondents reporting 3 or more was 7.2% (95% CI, 6.7%-7.7%) in 1998 and 7.3% (95% CI, 6.8%-7.9%) in 2008. The proportion of older adults reporting any ADL or IADL disability was 26.3% (95% CI, 25.4%-27.2%) in 1998 and 25.4% (95% CI, 24.5%-26.3%) in 2008.
Conclusions
Multiple chronic disease is increasingly prevalent among older U.S. adults, whereas the prevalence of impairment and disability, while substantial, remain stable.
doi:10.1186/1471-2318-11-47
PMCID: PMC3170191  PMID: 21851629
chronic disease; impairment; disability; prevalence trends
4.  Successful Aging in Older Adults with Schizophrenia: Prevalence and Associated Factors 
Objective
This study contrasts the prevalence of successful aging in older adults with schizophrenia with their age peers in the community, and examines variables associated with successful aging in the schizophrenia group.
Methods
The schizophrenia group consisted of 198 community-dwelling persons aged ≥55 years who developed schizophrenia before age 45. A community comparison group (N = 113) was recruited using randomly selected block-groups. The three objective criteria proposed by Rowe and Kahn were operationalized using a 6-item summed score. The association of 16 predictor variables with the successful aging score in the schizophrenia group was examined.
Results
The community group had significantly higher successful aging scores than the schizophrenia group (4.3 vs. 3.0; t =8.36, df =309, p< .001). Nineteen percent of the community group met all 6 criteria on the Successful Aging Score versus 2% of the schizophrenia group. In regression analysis, only two variables –fewer negative symptoms and a higher quality of life index—were associated with the successful aging score within the schizophrenia group.
Conclusion
Older adults with schizophrenia rarely achieve successful aging, and do so much less commonly than their age peers. Only two significant variables were associated with successful aging, neither of which are easily remediable. The elements that comprise the components of successful aging, especially physical health, may be better targets for intervention.
doi:10.1097/JGP.0b013e3181d57441
PMCID: PMC2946512  PMID: 20808093
successful aging; social integration; schizophrenia
5.  How “Successful” Do Older Europeans Age? Findings From SHARE 
Objectives.
We estimate comparable prevalence estimates of “successful aging” for 14 European countries and Israel, adding a new cross-nationally comparative perspective to recently published findings for the United States.
Methods.
Measures for a variety of specific successful aging criteria were derived from baseline interviews of respondents aged 65+ who participated in the Survey of Health, Ageing, and Retirement in Europe (n = 21,493). A multivariate logistic model was run for our global successful aging measure.
Results.
Our analysis revealed substantial cross-country variation around a mean value of 8.5%: Although as many as 21.1% of older Danes meet our successful aging criteria, the respective proportion in Poland is only 1.6%. Age, gender, and socioeconomic status are shown to bear highly significant associations with individuals’ odds of successful aging.
Discussion.
The observed cross-national variation in successful aging—which continues to exist if population composition is controlled for—highlights the importance of taking into consideration structural factors at the societal level. It also suggests a potential for policy interventions supporting individuals’ opportunities for successful aging.
doi:10.1093/geronb/gbq089
PMCID: PMC3041975  PMID: 21135069
Cross-national research; Population aging; SHARE; Successful aging
6.  Impact of social integration on metabolic functions: evidence from a nationally representative longitudinal study of US older adults 
BMC Public Health  2013;13:1210.
Background
Metabolic functions may operate as important biophysiological mechanisms through which social relationships affect health. It is unclear how social embeddedness or the lack thereof is related to risk of metabolic dysregulation. To fill this gap we tested the effects of social integration on metabolic functions over time in a nationally representative sample of older adults in the United States and examined population heterogeneity in the effects.
Methods
Using longitudinal data from 4,323 adults aged over 50 years in the Health and Retirement Study and latent growth curve models, we estimated the trajectories of social integration spanning five waves, 1998–2006, in relation to biomarkers of energy metabolism in 2006. We assessed social integration using a summary index of the number of social ties across five domains. We examined six biomarkers, including total cholesterol, high-density lipoprotein cholesterol, glycosylated hemoglobin, waist circumference, and systolic and diastolic blood pressure, and the summary index of the overall burden of metabolic dysregulation.
Results
High social integration predicted significantly lower risks of both individual and overall metabolic dysregulation. Specifically, adjusting for age, sex, race, and body mass index, having four to five social ties reduced the risks of abdominal obesity by 61% (odds ratio [OR] [95% confidence interval {CI}] = 0.39 [0.23, 0.67], p = .007), hypertension by 41% (OR [95% CI] = 0.59 [0.42, 0.84], p = .021), and the overall metabolic dysregulation by 46% (OR [95% CI] = 0.54 [0.40, 0.72], p < .001). The OR for the overall burden remained significant when adjusting for social, behavioral, and illness factors. In addition, stably high social integration had more potent metabolic impacts over time than changes therein. Such effects were consistent across subpopulations and more salient for the younger old (those under age 65), males, whites, and the socioeconomically disadvantaged.
Conclusions
This study addressed important challenges in previous research linking social integration to metabolic health by clarifying the nature and direction of the relationship as it applies to different objectively measured markers and population subgroups. It suggests additional psychosocial and biological pathways to consider in future research on the contributions of social deficits to disease etiology and old-age mortality.
doi:10.1186/1471-2458-13-1210
PMCID: PMC3923581  PMID: 24359332
Social integration; Social network size; Metabolic functions; Total cholesterol; High-density lipoprotein cholesterol; Glycosylated hemoglobin; Waist circumference; Blood pressure; Older adults
7.  The Prevalence of Cognitive Impairment in Older Adults with Heart Failure 
BACKGROUND
Our understanding of the prevalence of cognitive impairment (CI) in older adults with heart failure (HF) in a nationally-representative sample is limited.
OBJECTIVES
We used a national probability sample to determine the prevalence of CI in older adults with HF.
DESIGN
Cross-sectional analysis of the 2004 wave of the nationally representative Health and Retirement Study linked to 2002–04 Medicare administrative claims
SETTING
United States, community-dwelling
PARTICIPANTS
6,189 respondents ≥ 67 years old.
MEASUREMENTS
An algorithm was developed using a combination of self- and proxy-report of a heart problem and the presence of ≥ 1 Medicare claim in administrative files using standard HF diagnostic codes. On the basis of the algorithm, 3 categories were created to characterize the likelihood of a HF diagnosis: 1) High or Moderate Probability of HF; 2) Low Probability of HF; and 3) Not a HF case. Cognitive function was assessed using a screening measure of cognitive function or by proxy rating. Age-adjusted prevalence estimates of CI were calculated for the high-moderate probability HF group, the low probability HF group, and the non-HF cases.
RESULTS
The prevalence of CI consistent with dementia in older adults with HF was 15%; while the prevalence of mild CI was 24%. The odds of dementiain those with HF was significantly increased, even after adjustment for age, education level, net worth and prior stroke (OR: 1.52; 95% CI: 1.14 – 2.02).
CONCLUSION
CI is common in older adults with HF and is independently associated with an increased risk for dementia. A cognitive assessment should be routinely incorporated into HF-focused models of care.
doi:10.1111/j.1532-5415.2012.04097.x
PMCID: PMC3445700  PMID: 22882000
Heart failure; aged; cognitive impairment; Medicare claims data
8.  Alcohol Consumption at Midlife and Successful Ageing in Women: A Prospective Cohort Analysis in the Nurses' Health Study 
PLoS Medicine  2011;8(9):e1001090.
Using the Nurses' Health Study, Qi Sun and colleagues examine whether moderate alcohol intake is associated with overall health and well-being among women who survive to older age.
Background
Observational studies have documented inverse associations between moderate alcohol consumption and risk of premature death. It is largely unknown whether moderate alcohol intake is also associated with overall health and well-being among populations who have survived to older age. In this study, we prospectively examined alcohol use assessed at midlife in relation to successful ageing in a cohort of US women.
Methods and Findings
Alcohol consumption at midlife was assessed using a validated food frequency questionnaire. Subsequently, successful ageing was defined in 13,894 Nurses' Health Study participants who survived to age 70 or older, and whose health status was continuously updated. “Successful ageing” was considered as being free of 11 major chronic diseases and having no major cognitive impairment, physical impairment, or mental health limitations. Analyses were restricted to the 98.1% of participants who were not heavier drinkers (>45 g/d) at midlife. Of all eligible study participants, 1,491 (10.7%) achieved successful ageing. After multivariable adjustment of potential confounders, light-to-moderate alcohol consumption at midlife was associated with modestly increased odds of successful ageing. The odds ratios (95% confidence interval) were 1.0 (referent) for nondrinkers, 1.11 (0.96–1.29) for ≤5.0 g/d, 1.19 (1.01–1.40) for 5.1–15.0 g/d, 1.28 (1.03–1.58) for 15.1–30.0 g/d, and 1.24 (0.87–1.76) for 30.1–45.0 g/d. Meanwhile, independent of total alcohol intake, participants who drank alcohol at regular patterns throughout the week, rather than on a single occasion, had somewhat better odds of successful ageing; for example, the odds ratios (95% confidence interval) were 1.29 (1.01–1.64) and 1.47 (1.14–1.90) for those drinking 3–4 days and 5–7 days per week in comparison with nondrinkers, respectively, whereas the odds ratio was 1.10 (0.94–1.30) for those drinking only 1–2 days per week.
Conclusions
These data suggest that regular, moderate consumption of alcohol at midlife may be related to a modest increase in overall health status among women who survive to older ages.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
People have always drunk alcoholic beverages but throughout history there have been arguments about the risks and benefits of beer, wine, and spirits. It is clear that excessive alcohol use—heavy drinking (an average of more than two drinks per day for men or more than one drink per day for women; in the US, a “drink” is defined as 15 g of alcohol or, roughly speaking, a can of beer or a small glass of wine) or binge drinking (five or more drinks on a single occasion for men; 4 or more drinks at one time for women)—is harmful. It causes liver damage and increases the risk of developing some types of cancer. It contributes to depression and violence and interferes with relationships. And it is often implicated in fatal traffic accidents. However, in contrast to these and other harms associated with excessive alcohol use, moderate alcohol consumption seems to reduce the risk of specific diseases such as heart disease, stroke, and cognitive decline (deterioration in learning, reasoning, and perception).
Why Was This Study Done?
Although people who drink moderate amounts of alcohol have a reduced risk of premature death compared to abstainers or heavy drinkers, it is not known whether moderate alcohol consumption is associated with overall health among ageing populations. In many countries, elderly people are an increasingly large part of the population, so it is important to know how moderate alcohol consumption affects their well-being. In this study, the researchers examine the effect of alcohol consumption at midlife on successful ageing among the participants of the Nurses' Health Study. The researchers study the effect of midlife alcohol consumption because the chronic conditions that affect elderly people develop slowly and it is likely that factors in earlier life determine health in later life. Successful ageing is defined as being free of major chronic diseases such as cancer and heart disease, and having no major cognitive impairment, physical impairment, or mental health problems. The Nurses' Health Study enrolled 121,700 female registered nurses in 1976 to investigate the long-term effects of oral contraceptive use but has provided insights into many aspects of health and disease.
What Did the Researchers Do and Find?
The researchers assessed the alcohol consumption of the study participants at midlife (average age 58 years) from food frequency questionnaires completed in 1980 and 1984. Successful ageing for 13,984 participants who survived past 70 years was assessed by analyzing biennial health status questionnaires and cognitive function test results. One tenth of the women achieved successful ageing. After allowing for other factors that might affect their health such as smoking, women who drank light or moderate amounts of alcohol had a modestly increased chance of successful ageing compared to nondrinkers. For example, compared to nondrinkers, women who drank 5–15 g of alcohol per day (between one-third and one drink per day) had about a 20% higher chance of successful ageing. Independent of total alcohol intake, women who drank alcohol regularly had a better chance of successful ageing than occasional drinkers. Thus, compared to nondrinkers, women who drank five to seven days a week had nearly a 50% greater chance of successful ageing whereas women who drank only one or two days a week had a similar likelihood of successful ageing.
What Do These Findings Mean?
These findings suggest that regular, moderate consumption of alcohol at midlife may be related to a modest increase in overall health among women who survive to older ages. Because this is an observational study, it is possible that the women who drank moderately share other unknown characteristics that are actually responsible for their increased chance of successful ageing. Moreover, because all the study participants were women and most had European ancestry, these findings cannot be applied to men or to other ethnic groups. Nevertheless, these findings provide support for the 2010 US Department of Agriculture dietary guidelines, which state that consumption of up to one alcoholic drink per day for women and up to two alcoholic drinks per day for men may provide health benefits. Importantly, they also suggest that drinking alcohol regularly in moderation rather than occasional heavy drinking may be associated with a greater likelihood of successful ageing.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001090.
The US National Institute on Alcohol Abuse and Alcoholism has detailed information about alcohol and its effects on health, including a fact sheet on women and alcohol and a booklet entitled Alcohol, a woman's health issue
The US Centers for Disease Control and Prevention has a website on alcohol and public health
The UK National Health Service Choices website provides detailed information about drinking and alcohol, including how to calculate consumption
The Nutrition Source, a website maintained by the Department of Nutrition at Harvard School of Public Health, has an article entitled Alcohol: balancing risks and benefits
MedlinePlus provides links to many other resources on alcohol and on seniors' health
Details of the Nurses' Health Study are available
The 2010 US Department of Agriculture dietary guidelines are available
doi:10.1371/journal.pmed.1001090
PMCID: PMC3167795  PMID: 21909248
9.  Effect of the California Tobacco Control Program on Personal Health Care Expenditures 
PLoS Medicine  2008;5(8):e178.
Background
Large state tobacco control programs have been shown to reduce smoking and would be expected to affect health care costs. We investigate the effect of California's large-scale tobacco control program on aggregate personal health care expenditures in the state.
Methods and Findings
Cointegrating regressions were used to predict (1) the difference in per capita cigarette consumption between California and 38 control states as a function of the difference in cumulative expenditures of the California and control state tobacco control programs, and (2) the relationship between the difference in cigarette consumption and the difference in per capita personal health expenditures between the control states and California between 1980 and 2004. Between 1989 (when it started) and 2004, the California program was associated with $86 billion (2004 US dollars) (95% confidence interval [CI] $28 billion to $151 billion) lower health care expenditures than would have been expected without the program. This reduction grew over time, reaching 7.3% (95% CI 2.7%–12.1%) of total health care expenditures in 2004.
Conclusions
A strong tobacco control program is not only associated with reduced smoking, but also with reductions in health care expenditures.
Stanton Glantz and colleagues find that the California state tobacco control program is associated not only with reduced smoking, but with reductions in health care costs as well.
Editors' Summary
Background
According to the World Health Organization (WHO), tobacco causes 1 in 10 adult deaths worldwide and is the leading preventable cause of death in the world. In 2005, tobacco caused 5.4 million deaths, which amounts to one death every 6 seconds. It is estimated that by 2030, annual deaths from tobacco use will be 8 million worldwide. Eighty percent of these deaths will occur in the developing world.
Exposure to secondhand tobacco smoke is also a major health concern, as it can cause cancer, heart disease, and respiratory illness. An estimated 200,000 workers die annually from exposure to smoke at work, according to the International Labour Organization.
In 2008, the WHO released a report on the global tobacco epidemic, which provided a comprehensive analysis of tobacco use and control efforts. It revealed that not a single country fully implements all key tobacco control measures. The report also stated that governments around the world collect 500 times more money in tobacco taxes each year than they spend on anti-tobacco efforts.
The California Tobacco Control Program (CTCP) is a state-funded public policy intervention established in 1989. Its goal is to decrease tobacco-related diseases and deaths in California by reducing tobacco use across the state. The program is focused on adults and social norm change rather than on adolescent tobacco use prevention, on the premise that the “next generation cannot be saved without changing the generations who have already reached adulthood.”
Why Was This Study Done?
The success of large public health programs, especially those that counter the tactics of powerful industries such as the tobacco industry, require funding. The justification of public spending on these initiatives should be evidence driven. While the success of the CTCP in reducing smoking was known, it was not yet clear whether the program had reduced health care costs. The researchers investigated the effect of the CTCP on personal health care expenditures in the state. Their findings can provide useful information for the development of other tobacco control initiatives.
What Did the Researchers Do and Find?
Using the statistical approach of cointegrating regressions, the researchers modeled the relationships between per capita tobacco control expenditures, per capita cigarette consumption, and health care expenditures. They analyzed data from 1980 and 2004 on smoking, health care expenditures, and exposure to a tobacco control educational program in California and compared them to a group of 38 control states. Control states were those without comprehensive tobacco control programs prior to 2000 or cigarette tax increases of $0.50 or more per pack over the study period. This comparison allowed the researchers to assess the effect of the CTCP on total personal health care spending.
The researchers found that US$86 billion (95% CI $28 billion to $151 billion) were saved in personal health care expenditure between 1989, the start of the program, and 2004. This generally grew over time, reaching 7.3% of the total in 2003–2004. The personal health care expenditure savings represented about a 50-fold return on the $1.8 billion spent on the program during the same period (all 2004 US dollars).
The researchers report that 3.6 billion (95% CI 1.5 billion to 5.9 billion) fewer packs of cigarettes were sold between 1989–1990 and 2003–2004. This represents a loss of $9.2 billion (95% CI $3.8 billion to $14.7 billion) to the tobacco industry in pre-tax cigarette sales.
These cost savings occurred despite the substantial diversion of funding and decreased purchasing power experienced by the CTCP, particularly in the mid-1990s. (The program was funded with a constant tax of $0.05 per pack, despite inflation). The researchers estimated that if the funding, and thus purchasing power, had been maintained, total savings in personal health expenditures would have increased to $156 billion with an additional $70 billion in health cost savings. Cigarette consumption would have dropped to an estimated 6.6 billion packs.
What Do These Findings Mean?
The CTCP has been successful in reducing smoking in California in comparison to other states, and has reduced personal health care expenditures. These cost reductions were substantial, rapid, and grew over time. The researchers contend that the CTCP's focus on social norm change among adults, not primarily on youth prevention, is responsible for such rapid and large reductions in disease and the associated health care costs. They state that a program focused on primary prevention of smoking among adolescents would take decades to have any impact on tobacco-induced diseases, which rarely manifest among adolescents or even young adults. These researcher's findings support the establishment of strong tobacco control programs in other settings: they not only reduce smoking, prevent disease, and save lives, but also represent an important way to curb rapidly increasing health care expenditures in the short term.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050178.
The California Tobacco Control Program provides information about its social change approach
The WHO MPOWER strategy, detailed in the 2008 Report on the Global Tobacco Epidemic, outlines the six most effective policies to help curb the epidemic
Resources to help people quit smoking can be obtained through the US Centers for Disease Control and the UK National Health Service
doi:10.1371/journal.pmed.0050178
PMCID: PMC2522256  PMID: 18752344
10.  Disability Transitions and Health Expectancies among Adults 45 Years and Older in Malawi: A Cohort-Based Model 
PLoS Medicine  2013;10(5):e1001435.
Collin Payne and colleagues investigated development of disabilities and years expected to live with disabilities in participants 45 years and older participating in the Malawi Longitudinal Survey of Families and Health.
Please see later in the article for the Editors' Summary
Background
Falling fertility and increasing life expectancy contribute to a growing elderly population in sub-Saharan Africa (SSA); by 2060, persons aged 45 y and older are projected to be 25% of SSA's population, up from 10% in 2010. Aging in SSA is associated with unique challenges because of poverty and inadequate social supports. However, despite its importance for understanding the consequences of population aging, the evidence about the prevalence of disabilities and functional limitations due to poor physical health among older adults in SSA continues to be very limited.
Methods and Findings
Participants came from 2006, 2008, and 2010 waves of the Malawi Longitudinal Survey of Families and Health, a study of the rural population in Malawi. We investigate how poor physical health results in functional limitations that limit the day-to-day activities of individuals in domains relevant to this subsistence-agriculture context. These disabilities were parameterized based on questions from the SF-12 questionnaire about limitations in daily living activities. We estimated age-specific patterns of functional limitations and the transitions over time between different disability states using a discrete-time hazard model. The estimated transition rates were then used to calculate the first (to our knowledge) microdata-based health expectancies calculated for SSA. The risks of experiencing functional limitations due to poor physical health are high in this population, and the onset of disabilities happens early in life. Our analyses show that 45-y-old women can expect to spend 58% (95% CI, 55%–64%) of their remaining 28 y of life (95% CI, 25.7–33.5) with functional limitations; 45-y-old men can expect to live 41% (95% CI, 35%–46%) of their remaining 25.4 y (95% CI, 23.3–28.8) with such limitations. Disabilities related to functional limitations are shown to have a substantial negative effect on individuals' labor activities, and are negatively related to subjective well-being.
Conclusions
Individuals in this population experience a lengthy struggle with disabling conditions in adulthood, with high probabilities of remitting and relapsing between states of functional limitation. Given the strong association of disabilities with work efforts and subjective well-being, this research suggests that current national health policies and international donor-funded health programs in SSA inadequately target the physical health of mature and older adults.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The population of the world is getting older. In almost every country, the over-60 age group is growing faster than any other age group. In 2000, globally, there were about 605 million people aged 60 years or more; by 2050, 2 billion people will be in this age group. Much of this increase in the elderly population will be in low-income countries. In sub-Saharan Africa, for example, 10% of the population is currently aged 45 years or more, but by 2060, a quarter of the population will be so-called mature adults. In all countries, population aging is the result of women having fewer children (falling fertility) and people living longer (increasing life expectancy). Thus, population aging is a demographic transition, a change in birth and death rates. In low- and middle-income countries, population aging is occurring in parallel with an “epidemiological transition,” a shift from communicable (infectious) diseases to non-communicable diseases (for example, heart disease) as the primary causes of illness and death.
Why Was This Study Done?
Both the demographic and the epidemiological transition have public health implications for low-income countries. Good health is important for the independence and economic productivity of older people. Productive older people can help younger populations financially and physically, and help compensate for the limitations experienced by younger populations infected with HIV. Also, low-income countries lack social safety nets, so disabled older adults can be a burden on younger populations. Thus, the health of older individuals is important to the well-being of people of all ages. As populations age, low-income countries will need to invest in health care for mature and elderly adults and in disease prevention programs to prevent or delay the onset of non-communicable diseases, which can limit normal daily activities by causing disabilities. Before providing these services, national policy makers need to know the proportion of their population with disabilities, the functional limitations caused by poor physical health, and the health expectancies (the number of years a person can expect to be in good health) of older people in their country. In this cohort modeling study, the researchers estimate health expectancies and transition rates between different levels of disability among mature adults in Malawi, one of the world's poorest countries, using data collected by the Malawi Longitudinal Survey of Families and Health (MLSFH) on economic, social, and health conditions in a rural population. Because Malawi has shorter life expectancies and earlier onset of disability than wealthier countries, the authors considered individuals aged 45 and older as mature adults at risk for disability.
What Did the Researchers Do and Find?
The researchers categorized the participants in the 2006, 2008, and 2010 waves of the MLSFH into three levels of functional limitation (healthy, moderately limited, and severely limited) based on answers to questions in the SF-12 health survey questionnaire that ask about disabilities that limit daily activities that rural Malawians perform. The researchers estimated age–gender patterns of functional limitations and transition rates between different disability states using a discrete-time hazard model, and health expectancies by running a microsimulation to model the aging of synthetic cohorts with various starting ages but the same gender and functional limitation distributions as the study population. These analyses show that the chance of becoming physically disabled rises sharply with age, with 45-year-old women in rural Malawi expected to spend 58% of their estimated remaining 28 years with functional limitations, and 45-year-old men expected to live 41% of their remaining 25.4 years with functional limitations. Also, on average, a 45-year-old woman will spend 2.7 years with moderate functional limitation and 0.6 years with severe functional limitation before she reaches 55; for men the corresponding values are 1.6 and 0.4 years. Around 50% of moderately and 60%–80% of severely limited individuals stated that pain interfered quite a bit or extremely with their normal work during the past four weeks, suggesting that pain treatment may help reduce disability.
What Do These Findings Mean?
These findings suggest that mature adults in rural Malawi will have some degree of disability during much of their remaining lifetime. The risks of experiencing functional limitations are higher and the onset of persistent disabilities happens earlier in Malawi than in more developed contexts—the proportions of remaining life spent with severe limitations at age 45 in Malawi are comparable to those of 80-year-olds in the US. The accuracy of these findings is likely to be affected by assumptions made during modeling and by the quality of the data fed into the models. Nevertheless, these findings suggest that functional limitations, which have a negative effect on the labor activity of individuals, will become more prominent in Malawi (and probably other sub-Saharan countries) as the age composition of populations shifts over the coming years. Older populations in sub-Saharan Africa are not targeted well by health policies and programs at present. Consequently, these findings suggest that policy makers will need to ensure that additional financial resources are provided to improve health-care provision for aging individuals and to lessen the high rates of functional limitation and associated disabilities.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001435.
This study is further discussed in a PLoS Medicine Perspective by Andreas Stuck, et al.
The World Health Organization provides information on many aspects of aging (in several languages); the WHO Study on Global Ageing and Adult Health (SAGE) is compiling longitudinal information on the health and well-being of adult populations and the aging process
The United Nations Population Fund and HelpAge International publication Ageing in the Twenty-First Century is available
HelpAge International is an international nongovernmental organization that helps older people claim their rights, challenge discrimination, and overcome poverty, so that they can lead dignified, secure, and healthy lives
More information on the Malawi Longitudinal Study of Families and Health is available
doi:10.1371/journal.pmed.1001435
PMCID: PMC3646719  PMID: 23667343
11.  In Vitro Fertilization and Multiple Pregnancies 
Executive Summary
Objective
The objective of this health technology policy assessment was to determine the clinical effectiveness and cost-effectiveness of IVF for infertility treatment, as well as the role of IVF in reducing the rate of multiple pregnancies.
Clinical Need: Target Population and Condition
Typically defined as a failure to conceive after a year of regular unprotected intercourse, infertility affects 8% to 16% of reproductive age couples. The condition can be caused by disruptions at various steps of the reproductive process. Major causes of infertility include abnormalities of sperm, tubal obstruction, endometriosis, ovulatory disorder, and idiopathic infertility. Depending on the cause and patient characteristics, management options range from pharmacologic treatment to more advanced techniques referred to as assisted reproductive technologies (ART). ART include IVF and IVF-related procedures such as intra-cytoplasmic sperm injection (ICSI) and, according to some definitions, intra-uterine insemination (IUI), also known as artificial insemination. Almost invariably, an initial step in ART is controlled ovarian stimulation (COS), which leads to a significantly higher rate of multiple pregnancies after ART compared with that following natural conception. Multiple pregnancies are associated with a broad range of negative consequences for both mother and fetuses. Maternal complications include increased risk of pregnancy-induced hypertension, pre-eclampsia, polyhydramnios, gestational diabetes, fetal malpresentation requiring Caesarean section, postpartum haemorrhage, and postpartum depression. Babies from multiple pregnancies are at a significantly higher risk of early death, prematurity, and low birth weight, as well as mental and physical disabilities related to prematurity. Increased maternal and fetal morbidity leads to higher perinatal and neonatal costs of multiple pregnancies, as well as subsequent lifelong costs due to disabilities and an increased need for medical and social support.
The Technology Being Reviewed
IVF was first developed as a method to overcome bilateral Fallopian tube obstruction. The procedure includes several steps: (1) the woman’s egg is retrieved from the ovaries; (2) exposed to sperm outside the body and fertilized; (3) the embryo(s) is cultured for 3 to 5 days; and (4) is transferred back to the uterus. IFV is considered to be one of the most effective treatments for infertility today. According to data from the Canadian Assisted Reproductive Technology Registry, the average live birth rate after IVF in Canada is around 30%, but there is considerable variation in the age of the mother and primary cause of infertility.
An important advantage of IVF is that it allows for the control of the number of embryos transferred. An elective single embryo transfer in IVF cycles adopted in many European countries was shown to significantly reduce the risk of multiple pregnancies while maintaining acceptable birth rates. However, when number of embryos transferred is not limited, the rate of IVF-associated multiple pregnancies is similar to that of other treatments involving ovarian stimulation. The practice of multiple embryo transfer in IVF is often the result of pressures to increase success rates due to the high costs of the procedure. The average rate of multiple pregnancies resulting from IVF in Canada is currently around 30%.
An alternative to IVF is IUI. In spite of reported lower success rates of IUI (pregnancy rates per cycle range from 8.7% to 17.1%) it is generally attempted before IVF due to its lower invasiveness and cost.
Two major drawbacks of IUI are that it cannot be used in cases of bilateral tubal obstruction and it does not allow much control over the risk of multiple pregnancies compared with IVF. The rate of multiple pregnancies after IUI with COS is estimated to be about 21% to 29%.
Ontario Health Insurance Plan Coverage
Currently, the Ontario Health Insurance Plan covers the cost of IVF for women with bilaterally blocked Fallopian tubes only, in which case it is funded for 3 cycles, excluding the cost of drugs. The cost of IUI is covered except for preparation of the sperm and drugs used for COS.
Diffusion of Technology
According to Canadian Assisted Reproductive Technology Registry data, in 2004 there were 25 infertility clinics across Canada offering IVF and 7,619 IVF cycles performed. In Ontario, there are 13 infertility clinics with about 4,300 IVF cycles performed annually.
Literature Review
Royal Commission Report on Reproductive Technologies
The 1993 release of the Royal Commission report on reproductive technologies, Proceed With Care, resulted in the withdrawal of most IVF funding in Ontario, where prior to 1994 IVF was fully funded. Recommendations of the Commission to withdraw IVF funding were largely based on findings of the systematic review of randomized controlled trials (RCTs) published before 1990. The review showed IVF effectiveness only in cases of bilateral tubal obstruction. As for nontubal causes of infertility, there was not enough evidence to establish whether IVF was effective or not.
Since the field of reproductive technology is constantly evolving, there have been several changes since the publication of the Royal Commission report. These changes include: increased success rates of IVF; introduction of ICSI in the early 1990’s as a treatment for male factor infertility; and improved embryo implantation rates allowing for the transfer of a single embryo to avoid multiple pregnancies after IVF.
Studies After the Royal Commission Report: Review Strategy
Three separate literature reviews were conducted in the following areas: clinical effectiveness of IVF, cost-effectiveness of IVF, and outcomes of single embryo transfer (SET) in IVF cycles.
Clinical effectiveness of IVF: RCTs or meta-analyses of RCTs that compared live birth rates after IVF versus alternative treatments, where the cause of infertility was clearly stated or it was possible to stratify the outcome by the cause of infertility.
Cost effectiveness of IVF: All relevant economic studies comparing IVF to alternative methods of treatment were reviewed
Outcomes of IVF with SET: RCTs or meta-analyses of RCTs that compared live birth rates and multiple birth rates associated with transfer of single versus double embryos.
OVID MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Cochrane Library, the International Agency for Health Technology Assessment database, and websites of other health technology assessment agencies were searched using specific subject headings and keywords to identify relevant studies.
Summary of Findings
Comparative Clinical Effectiveness of IVF
Overall, there is a lack of well composed RCTs in this area and considerable diversity in both definition and measurement of outcomes exists between trials. Many studies used fertility or pregnancy rates instead of live birth rates. Moreover, the denominator for rate calculation varied from study to study (e.g. rates were calculated per cycle started, per cycle completed, per couple, etc...).
Nevertheless, few studies of sufficient quality were identified and categorized by the cause of infertility and existing alternatives to IVF. The following are the key findings:
A 2005 meta-analysis demonstrated that, in patients with idiopathic infertility, IVF was clearly superior to expectant management, but there were no statistically significant differences in live birth rates between IVF and IUI, nor between IVF and gamete-intra-Fallopian transfer.
A subset of data from a 2000 study showed no significant differences in pregnancy rates between IVF and IUI for moderate male factor infertility.
In patients with moderate male factor infertility, standard IVF was also compared with ICSI in a 2002 meta-analysis. All studies included in the meta-analysis showed superior fertilization rates with ICSI, and the pooled risk ratio for oocyte fertilization was 1.9 (95% Confidence Interval 1.4-2.5) in favour of ICSI. Two other RCTs in this area published after the 2002 meta-analysis had similar results and further confirmed these findings. There were no RCTs comparing IVF with ICSI in patients with severe male factor infertility, mainly because based on the expert opinion, ICSI might only be an effective treatment for severe male factor infertility.
Cost-Effectiveness of IVF
Five economic evaluations of IVF were found, including one comprehensive systematic review of 57 health economic studies. The studies compared cost-effectiveness of IVF with a number of alternatives such as observation, ovarian stimulation, IUI, tubal surgery, varicocelectomy, etc... The cost-effectiveness of IVF was analyzed separately for different types of infertility. Most of the reviewed studies concluded that due to the high cost, IVF has a less favourable cost-effectiveness profile compared with alternative treatment options. Therefore, IVF was not recommended as the first line of treatment in the majority of cases. The only two exceptions were bilateral tubal obstruction and severe male factor infertility, where an immediate offer of IVF/ICSI might the most cost-effective option.
Clinical Outcomes After Single Versus Double Embryo Transfer Strategies of IVF
Since the SET strategy has been more widely adopted in Europe, all RCT outcomes of SET were conducted in European countries. The major study in this area was a large 2005 meta-analysis, followed by two other published RCTs.
All of these studies reached similar conclusions:
Although a single SET cycle results in lower birth rates than a single double embryo transfer (DET) cycle, the cumulative birth rate after 2 cycles of SET (fresh + frozen-thawed embryos) was comparable to the birth rate after a single DET cycle (~40%).
SET was associated with a significant reduction in multiple births compared with DET (0.8% vs. 33.1% respectively in the largest RCT).
Most trials on SET included women younger than 36 years old with a sufficient number of embryos available for transfer that allowed for selection of the top quality embryo(s). A 2006 RCT, however, compared SET and DET strategies in an unselected group of patients without restrictions on the woman’s age or embryo quality. This study demonstrated that SET could be applied to older women.
Estimate of the Target Population
Based on results of the literature review and consultations with experts, four categories of infertile patients who may benefit from increased access to IVF/ICSI were identified:
Patients with severe male factor infertility, where IVF should be offered in conjunction with ICSI;
Infertile women with serious medical contraindications to multiple pregnancy, who should be offered IVF-SET;
Infertile patients who want to avoid the risk of multiple pregnancy and thus opt for IVF-SET; and
Patients who failed treatment with IUI and wish to try IVF.
Since, however, the latter indication does not reflect any new advances in IVF technology that would alter existing policy, it was not considered in this analysis.
Economic Analysis
Economic Review: Cost–Effectiveness of SET Versus DET
Conclusions of published studies on cost-effectiveness of SET versus DET were not consistent. While some studies found that SET strategy is more cost-effective due to avoidance of multiple pregnancies, other studies either did not find any significant differences in cost per birth between SET and DET, or favoured DET as a more cost-effective option.
Ontario-Based Economic Analysis
An Ontario-based economic analysis compared cost per birth using three treatment strategies: IUI, IVF-SET, and IVF-DET. A decision-tree model assumed three cycles for each treatment option. Two separate models were considered; the first included only fresh cycles of IVF, while the second had a combination of fresh and frozen cycles. Even after accounting for cost-savings due to avoidance of multiple pregnancies (only short-term complications), IVF-SET was still associated with a highest cost per birth. The approximate budget impact to cover the first three indications for IVF listed above (severe male factor infertility, women with medical contraindications to multiple pregnancy, and couples who wish to avoid the risk of multiple pregnancy) is estimated at $9.8 to $12.8 million (Cdn). Coverage of only first two indications, namely, ICSI in patients with severe male factor infertility and infertile women with serious medical contraindications to multiple pregnancy, is estimated at $3.8 to $5.5 million Cdn.
Other Considerations
International data shows that both IVF utilization and the average number of embryos transferred in IVF cycles are influenced by IVF funding policy. The success of the SET strategy in European countries is largely due to the fact that IVF treatment is subsidized by governments.
Surveys of patients with infertility demonstrated that a significant proportion (~40%) of patients not only do not mind having multiple babies, but consider twins being an ideal outcome of infertility treatment.
A women’s age may impose some restrictions on the implementation of a SET strategy.
Conclusions and Recommendations
A review of published studies has demonstrated that IVF-SET is an effective treatment for infertility that avoids multiple pregnancies.
However, results of an Ontario-based economic analysis shows that cost savings associated with a reduction in multiple pregnancies after IVF-SET does not justify the cost of universal IVF-SET coverage by the province. Moreover, the province currently funds IUI, which has been shown to be as effective as IVF for certain types of infertility and is significantly less expensive.
In patients with severe male factor infertility, IVF in conjunction with ICSI may be the only effective treatment.
Thus, 2 indications where additional IVF access should be considered include:
IVF/ICSI for patients with severe male factor infertility
IVF-SET in infertile women with serious medical contraindications to multiple pregnancy
PMCID: PMC3379537  PMID: 23074488
12.  The Older They Are, the Less Successful They Become? Findings from the Georgia Centenarian Study 
Journal of Aging Research  2012;2012:695854.
This study examined whether oldest-old adults are successful agers. Three hundred and six octogenarians and centenarians of Phase III of the Georgia Centenarian Study participated in this study. A first model examined Rowe and Kahn's successful aging model (Rowe and Khan (1997 and 1998)) including the probability of disease, physical or cognitive capacity, and engagement with life. All three components were applied to assess how many oldest-old adults satisfied all three criteria. The result showed about 15% of octogenarians (15.1%), and none of centenarians satisfied all three components of successful aging. Consequently, a second alternative model focused on psychosocial aspects including three different components: subjective health, perceived economic status, and happiness. Different from Rowe and Kahn's successful aging model, a total of 62.3% of octogenarians and 47.5% of centenarians satisfied all three components of the alternative model of successful aging. The results suggest that additional criteria of successful aging should be considered thereby expanding the concepts and multidimensional aspects of successful aging among oldest-old adults.
doi:10.1155/2012/695854
PMCID: PMC3414058  PMID: 22900178
13.  An Examination of Healthy Aging Across a Conceptual Continuum: Prevalence Estimates, Demographic Patterns, and Validity 
Background.
Although the notion of healthy aging has gained wide acceptance in gerontology, measuring the phenomenon is challenging. Guided by a prominent conceptualization of healthy aging, we examined how shifting from a more to less stringent definition of healthy aging influences prevalence estimates, demographic patterns, and validity.
Methods.
Data are from adults aged 65 years and older who participated in the Health and Retirement Study. We examined four operational definitions of healthy aging. For each, we calculated prevalence estimates and examined the odds of healthy aging by age, education, gender, and race-ethnicity in 2006. We also examined the association between healthy aging and both self-rated health and death.
Results.
Across definitions, the prevalence of healthy aging ranged from 3.3% to 35.5%. For all definitions, those classified as experiencing healthy aging had lower odds of fair or poor self-rated health and death over an 8-year period. The odds of being classified as “healthy” were lower among those of advanced age, those with less education, and women than for their corresponding counterparts across all definitions.
Conclusions.
Moving across the conceptual continuum—from a more to less rigid definition of healthy aging—markedly increases the measured prevalence of healthy aging. Importantly, results suggest that all examined definitions identified a subgroup of older adults who had substantially lower odds of reporting fair or poor health and dying over an 8-year period, providing evidence of the validity of our definitions. Conceptualizations that emphasize symptomatic disease and functional health may be particularly useful for public health purposes.
doi:10.1093/gerona/glr234
PMCID: PMC3536546  PMID: 22367432
Healthy aging; Measurement; Successful aging
14.  Effects of Community-Wide Vaccination with PCV-7 on Pneumococcal Nasopharyngeal Carriage in The Gambia: A Cluster-Randomized Trial 
PLoS Medicine  2011;8(10):e1001107.
In a cluster-randomized trial conducted in Gambian villages, Anna Roca and colleagues find that vaccination of children with pneumococcal conjugate vaccines reduced vaccine-type pneumococcal carriage even among nonvaccinated older children and adults.
Background
Introduction of pneumococcal conjugate vaccines (PCVs) of limited valency is justified in Africa by the high burden of pneumococcal disease. Long-term beneficial effects of PCVs may be countered by serotype replacement. We aimed to determine the impact of PCV-7 vaccination on pneumococcal carriage in rural Gambia.
Methods and Findings
A cluster-randomized (by village) trial of the impact of PCV-7 on pneumococcal nasopharyngeal carriage was conducted in 21 Gambian villages between December 2003 to June 2008 (5,441 inhabitants in 2006). Analysis was complemented with data obtained before vaccination. Because efficacy of PCV-9 in young Gambian children had been shown, it was considered unethical not to give PCV-7 to young children in all of the study villages. PCV-7 was given to children below 30 mo of age and to those born during the trial in all study villages. Villages were randomized (older children and adults) to receive one dose of PCV-7 (11 vaccinated villages) or meningococcal serogroup C conjugate vaccine (10 control villages). Cross-sectional surveys (CSSs) to collect nasopharyngeal swabs were conducted before vaccination (2,094 samples in the baseline CSS), and 4–6, 12, and 22 mo after vaccination (1,168, 1,210, and 446 samples in CSS-1, -2, and -3, respectively).
A time trend analysis showed a marked fall in the prevalence of vaccine-type pneumococcal carriage in all age groups following vaccination (from 23.7% and 26.8% in the baseline CSS to 7.1% and 8.5% in CSS-1, in vaccinated and control villages, respectively). The prevalence of vaccine-type pneumococcal carriage was lower in vaccinated than in control villages among older children (5 y to <15 y of age) and adults (≥15 y of age) at CSS-2 (odds ratio [OR] = 0.15 [95% CI 0.04–0.57] and OR = 0.32 [95% CI 0.10–0.98], respectively) and at CSS-3 (OR = 0.37 [95% CI 0.15–0.90] for older children, and 0% versus 7.6% for adults in vaccinated and control villages, respectively). Differences in the prevalence of non-vaccine-type pneumococcal carriage between vaccinated and control villages were small.
Conclusions
Vaccination of Gambian children reduced vaccine-type pneumococcal carriage across all age groups, indicating a “herd effect” in non-vaccinated older children and adults. No significant serotype replacement was detected.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The prevention of pneumococcal disease, especially in children in developing countries, is a major international public health priority. Despite all the international attention on the UN's Millennium Development Goal 4—to reduce deaths in children under five years by two-thirds between 1990 and 2015—pneumonia, sepsis, and meningitis together compose more than 25% of the 10 million deaths occurring in children less than five years of age. Streptococcus pneumoniae is a leading bacterial cause of these diseases, and the World Health Organization estimates that approximately 800,000 children die each year of invasive pneumococcal disease.
Pneumococcal conjugate vaccines are currently available and protect against the serotypes that most commonly cause invasive pneumococcal disease in young children in North America and Europe. Such vaccines have been highly successful in reducing the incidence of invasive pneumococcal disease in both vaccinated children and in the non-vaccinated older population by reducing nasopharyngeal carriage (presence of pneumococcal bacteria in the back of the nose) in vaccinated infants, resulting in decreased transmission to contacts—the so-called herd effect. However, few countries with the highest burden of invasive pneumococcal disease, especially those in sub-Saharan Africa, have introduced the vaccine into their national immunization programs.
Why Was This Study Done?
The features of pneumococcal nasopharyngeal carriage and invasive pneumococcal disease in sub-Saharan Africa are different than in other regions. Therefore, careful evaluation of the immune effects of vaccination requires long-term, longitudinal studies. As an alternative to such long-term observational studies, and to anticipate the potential long-term effects of the introduction of pneumococcal conjugate vaccination in sub-Saharan Africa, the researchers conducted a cluster-randomized (by village) trial in The Gambia in which the whole populations of some villages were immunized with the vaccine PCV-7, and other villages received a control.
What Did the Researchers Do and Find?
With full consent from communities, the researchers randomized 21 similar villages in a rural region of western Gambia to receive pneumococcal conjugate vaccine or a control—meningococcal serogroup C conjugated vaccine, which is unlikely to affect pneumococcal carriage rates. For ethical reasons, the researchers only randomized residents aged over 30 months—all young infants received PCV-7, as a similar vaccine had already been shown to be effective in young infants. Before immunization began, the researchers took nasopharyngeal swabs from a random selection of village residents to determine the baseline pneumococcal carriage rates of both the serotypes of pneumococci covered by the vaccine (vaccine types, VTs) and the serotypes of pneumococci not covered in the vaccine (non-vaccine types, NVTs). The researchers then took nasopharyngeal swabs from a random sample of 1,200 of village residents in both groups of villages in cross-sectional surveys at 4–6, 12, and 22 months after vaccination. Villagers and laboratory staff were unaware of which vaccine was which (that is, they were blinded).
Before immunization, the overall prevalence of pneumococcal carriage in both groups was high, at 71.1%, and decreased with age. After vaccination, the overall prevalence of pneumococcal carriage in all three surveys was similar between vaccinated and control villages, showing a marked fall. However, the prevalence of carriage of VT pneumococci was significantly lower in vaccinated than in control villages in all surveys for all age groups. The prevalence of carriage of NVT pneumococci was similar in vaccinated and in control villages, except for a slightly higher prevalence of NVT pneumococci among vaccinated communities in adults at 4–6 months after vaccination. The researchers also found that the overall prevalence of pneumococcal carriage fell markedly after vaccination and reached minimum levels at 12 months in both study arms and in all age groups.
What Do These Findings Mean?
These findings show that vaccination of young Gambian children reduced carriage of VT pneumococci in vaccinated children but also in vaccinated and non-vaccinated older children and adults, revealing a potential herd effect from vaccination of young children. Furthermore, the immunological pressure induced by vaccinating whole communities did not lead to a community-wide increase in carriage of NVT pneumococci during a two-year period after vaccination. The researchers plan to conduct more long-term follow-up studies to determine nasopharyngeal carriage in these communities.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001107.
The World Health Organization has information about pneumococcus
The US Centers for Disease Control and Prevention provides information about pneumococcal conjugate vaccination
doi:10.1371/journal.pmed.1001107
PMCID: PMC3196470  PMID: 22028630
17.  The Kahn Test: A Simplified Technique 
British Medical Journal  1940;1(4128):252-253.
PMCID: PMC2176627  PMID: 20782956
25.  Value of the Kahn Test in Africans* 
PMCID: PMC1054044  PMID: 13276638

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