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1.  The Impact of Disability on the Lives of Children; Cross-Sectional Data Including 8,900 Children with Disabilities and 898,834 Children without Disabilities across 30 Countries 
PLoS ONE  2014;9(9):e107300.
Background
Children with disabilities are widely believed to be less likely to attend school or access health care, and more vulnerable to poverty. There is currently little large-scale or internationally comparable evidence to support these claims. The aim of this study was to investigate the impact of disability on the lives of children sponsored by Plan International across 30 countries.
Methods and Findings
We conducted a cross-sectional survey including 907,734 children aged 0–17 participating in the Plan International Sponsorship Programme across 30 countries in 2012. Parents/guardians were interviewed using standardised questionnaires including information on: age, sex, health, education, poverty, and water and sanitation facilities. Disability was assessed through a single question and information was collected on type of impairment. The dataset included 8,900 children with reported disabilities across 30 countries. The prevalence of disability ranged from 0.4%–3.0% and was higher in boys than girls in 22 of the 30 countries assessed – generally in the range of 1.3–1.4 fold higher. Children with disabilities were much less likely to attend formal education in comparison to children without disabilities in each of the 30 countries, with age-sex adjusted odds ratios exceeding 10 for nearly half of the countries. This relationship varied by impairment type. Among those attending school, children with disabilities were at a lower level of schooling for their age compared to children without disabilities. Children with disabilities were more likely to report experiencing a serious illness in the last 12 months, except in Niger. There was no clear relationship between disability and poverty.
Conclusions
Children with disabilities are at risk of not fulfilling their educational potential and are more vulnerable to serious illness. This exclusion is likely to have a long-term deleterious impact on their lives unless services are adapted to promote their inclusion.
doi:10.1371/journal.pone.0107300
PMCID: PMC4159292  PMID: 25202999
2.  The Nakuru eye disease cohort study: methodology & rationale 
BMC Ophthalmology  2014;14:60.
Background
No longitudinal data from population-based studies of eye disease in sub-Saharan-Africa are available. A population-based survey was undertaken in 2007/08 to estimate the prevalence and determinants of blindness and low vision in Nakuru district, Kenya. This survey formed the baseline to a six-year prospective cohort study to estimate the incidence and progression of eye disease in this population.
Methods/Design
A nationally representative sample of persons aged 50 years and above were selected between January 2007 and November 2008 through probability proportionate to size sampling of clusters, with sampling of individuals within clusters through compact segment sampling. Selected participants underwent detailed ophthalmic examinations which included: visual acuity, autorefraction, visual fields, slit lamp assessment of the anterior and posterior segments, lens grading and fundus photography. In addition, anthropometric measures were taken and risk factors were assessed through structured interviews. Six years later (2013/2014) all subjects were invited for follow-up assessment, repeating the baseline examination methodology.
Discussion
The methodology will provide estimates of the progression of eye diseases and incidence of blindness, visual impairment, and eye diseases in an adult Kenyan population.
doi:10.1186/1471-2415-14-60
PMCID: PMC4024270  PMID: 24886366
Cohort study; Longitudinal; Eye disease; Africa; Kenya; Cataract; Glaucoma; Age related macular degeneration; Diabetic retinopathy; Refractive error; Incidence; Progression
3.  The Long Term Impact of Cataract Surgery on Quality of Life, Activities and Poverty: Results from a Six Year Longitudinal Study in Bangladesh and the Philippines 
PLoS ONE  2014;9(4):e94140.
Background
Cataract surgery has been shown to improve quality of life and household economy in the short term. However, it is unclear whether these benefits are sustained over time. This study aims to assess the six year impact of cataract surgery on health related quality of life (HRQoL), daily activities and economic poverty in Bangladesh and The Philippines.
Methods and Findings
This was a longitudinal study. At baseline people aged ≥50 years with visual impairment due to cataract (‘cases’) and age-, sex-matched controls without visual impairment were interviewed about vision specific and generic HRQoL, daily activities and economic indicators (household per capita expenditure, assets and self-rated wealth). Cases were offered free or subsidised cataract surgery. Cases and controls were re-interviewed approximately one and six years later. At baseline across the two countries there were 455 cases and 443 controls. Fifty percent of cases attended for surgery. Response rates at six years were 47% for operated cases and 53% for controls. At baseline cases had poorer health and vision related QoL, were less likely to undertake productive activities, more likely to receive assistance with activities and were poorer compared to controls (p<0.05). One year after surgery there were significant increases in HRQoL, participation and time spent in productive activities and per capita expenditure and reduction in assistance with activities so that the operated cases were similar to controls. These increases were still evident after six years with the exception that time spent on productive activities decreased among both cases and controls.
Conclusion
Cataract causing visual loss is associated with reduced HRQoL and economic poverty among older adults in low-income countries. Cataract surgery improves the HRQoL of the individual and economy of the household. The findings of this study suggest these benefits are sustained in the long term.
doi:10.1371/journal.pone.0094140
PMCID: PMC3991652  PMID: 24747192
4.  Life-course determinants of bone mass in young adults from a transitional rural community in India: the Andhra Pradesh Children and Parents Study (APCAPS)123 
Background: Undernutrition and physical inactivity are both associated with lower bone mass.
Objective: This study aimed to investigate the combined effects of early-life undernutrition and urbanized lifestyles in later life on bone mass accrual in young adults from a rural community in India that is undergoing rapid socioeconomic development.
Design: This was a prospective cohort study of participants of the Hyderabad Nutrition Trial (1987–1990), which offered balanced protein-calorie supplementation to pregnant women and preschool children younger than 6 y in the intervention villages. The 2009–2010 follow-up study collected data on current anthropometric measures, bone mineral density (BMD) measured by dual-energy X-ray absorptiometry, blood samples, diet, physical activity, and living standards of the trial participants (n = 1446, aged 18–23 y).
Results: Participants were generally lean and had low BMD [mean hip BMD: 0.83 (women), 0.95 (men) g/cm2; lumbar spine: 0.86 (women), 0.93 (men) g/cm2]. In models adjusted for current risk factors, no strong evidence of a positive association was found between BMD and early-life supplementation. On the other hand, current lean mass and weight-bearing physical activity were positively associated with BMD. No strong evidence of an association was found between BMD and current serum 25-hydroxyvitamin D or dietary intake of calcium, protein, or calories.
Conclusions: Current lean mass and weight-bearing physical activity were more important determinants of bone mass than was early-life undernutrition in this population. In transitional rural communities from low-income countries, promotion of physical activity may help to mitigate any potential adverse effects of early nutritional disadvantage.
doi:10.3945/ajcn.113.068791
PMCID: PMC4021785  PMID: 24695898
5.  The Association of Early Life Supplemental Nutrition With Lean Body Mass and Grip Strength in Adulthood: Evidence From APCAPS 
American Journal of Epidemiology  2014;179(6):700-709.
In the present study, we examined the associations of early nutrition with adult lean body mass (LBM) and muscle strength in a birth cohort that was established to assess the long-term impact of a nutrition program. Participants (n = 1,446, 32% female) were born near Hyderabad, India, in 29 villages from 1987 to 1990, during which time only intervention villages (n = 15) had a government program that offered balanced protein-calorie supplementation to pregnant women and children. Participants’ LBM and appendicular skeletal muscle mass were measured using dual energy x-ray absorptiometry; grip strength and information on lifestyle indicators, including diet and physical activity level, were also obtained. Ages (mean = 20.3 years) and body mass indexes (weight (kg)/height (m)2; mean = 19.5) of participants in 2 groups were similar. Current dietary energy intake was higher in the intervention group. Unadjusted LBM and grip strength were similar in 2 groups. After adjustment for potential confounders, the intervention group had lower LBM (β = −0.75; P = 0.03), appendicular skeletal muscle mass, and grip strength than did controls, but these differences were small in magnitude (<0.1 standard deviation). Multivariable regression analyses showed that current socioeconomic position, energy intake, and physical activity level had a positive association with adult LBM and muscle strength. This study could not detect a “programming” effect of early nutrition supplementation on adult LBM and muscle strength.
doi:10.1093/aje/kwt332
PMCID: PMC3939852  PMID: 24553777
body composition; cohort study; developmental origins of health and disease; grip strength; lean body mass; muscle mass; nutrition; physical activity
7.  HIV and Childhood Disability: A Case-Controlled Study at a Paediatric Antiretroviral Therapy Centre in Lilongwe, Malawi 
PLoS ONE  2013;8(12):e84024.
Background
As paediatric antiretroviral therapy (ART) is rapidly scaled up in Southern Africa, Human Immunodeficiency Virus (HIV) infection is becoming a chronic illness. Children growing up with HIV may begin to encounter disabilities. The relationship between HIV, disability and the need for rehabilitation has added an additional element that needs to be addressed by paediatric HIV treatment programmes.
Study Objectives
1) Estimate the prevalence of disabilities in HIV-infected and HIV-uninfected children in Lilongwe, Malawi. 2) Examine types of disability and associated clinical and socio-demographic factors. 3) Identify needs, opportunities and barriers for rehabilitation in Malawi.
Methods
A case-controlled study of 296 HIV-infected children aged 2–9 years attending an ART centre in Lilongwe (cases) and their uninfected siblings (controls) was conducted. Disability was assessed using the WHO Ten Question Screen (TQS). Socio-demographic and clinical data were collected using a parent-proxy questionnaire and medical records.
Results
Of 296 case and control pairs recruited, 33% (98) versus 7% (20) screened positive for a disability (OR 8.4, 4.4–15.7) respectively. Of these 98 HIV-infected cases, 6%, 36%, 33%, 53%, 46% and 6% had a vision, hearing; physical, learning/comprehension, speech or seizure-related disability respectively and 51% had multiple coexisting disabilities. HIV-infected cases with a disability were more likely to be WHO stage III or IV at enrolment (71% vs. 52%, OR 2.7, 1.5–4.2), to have had TB (58% vs. 39%, OR 2.3, 1.4–3.8) and to have below-average school grades (18% vs. 2%, OR 11.1, 2.2–54.6) than those without. Sixty-seven percent of cases with a disability had never attended any rehabilitative service. Twenty-nine percent of caregivers reported facing stigma and discrimination because of the child’s disability.
Conclusion
This study reveals the magnitude of disability among HIV-infected children and the large unmet need for rehabilitation services. This expanding issue demands further investigation to provide an evidence base for holistic care for disabled children living with HIV.
doi:10.1371/journal.pone.0084024
PMCID: PMC3877142  PMID: 24391869
8.  The effect of rural-to-urban migration on renal function in an Indian population: cross-sectional data from the Hyderabad arm of the Indian Migration Study 
BMC Nephrology  2013;14:240.
Background
Urban migration is associated with an increased risk of hypertension, obesity and diabetes in Indian migrants. This study assessed the relationship between internal migration and renal function in the Hyderabad arm of the Indian Migration Study.
Methods
We assessed 841 subjects; urban non-migrants (n = 158), urban migrants (n = 424) and rural non-migrants (n = 259). Muscle mass was ascertained from DXA scanning. We derived urban life years for urban migrants and rural non-migrants. Multivariable linear regression was used to examine the association between tertiles of urban life years and 4-variable MDRD eGFR using Stata 11.
Results
Mean eGFR was lower in urban non-migrants and urban migrants compared to rural non-migrants. The prevalence of CKD 3-5 was higher in the rural non-migrant population (5.0%) than in the urban non-migrant populations (2.5%) due to a negatively skewed distribution of eGFR in rural non-migrants. As urban life years increased, eGFR declined (p = 0.008) though there was no obvious dose response effect. After adjustment for muscle mass, the association was attenuated and the trend was consistent with chance (p = 0.08). Further adjustment for vascular risk factors weakened the association to a small degree (p = 0.11).
Conclusions
The high prevalence of reduced eGFR in rural areas requires further research. Urbanization was associated with reduced eGFR. This association appears mostly to be due to higher muscle mass with a small contribution from adverse vascular disease risk factors.
doi:10.1186/1471-2369-14-240
PMCID: PMC4228419  PMID: 24176058
9.  Prevalence, Types, Risk Factors and Clinical Correlates of Anaemia in Older People in a Rural Ugandan Population 
PLoS ONE  2013;8(10):e78394.
Background
Studies conducted in high income countries have shown that anaemia is a common medical condition among older people, but such data are scarce in Africa. The objectives of this study were to estimate the prevalence, types, risk factors and clinical correlates of anaemia in older people.
Methods
Participants were aged (≥ 50) years recruited from a general population cohort from January 2012 to January 2013. Blood samples were collected for assessing hemoglobin, serum ferritin, serum vitamin B12, serum folate, C-reactive protein, malaria infection and stool samples for assessment of hookworm infection. HIV status was assessed using an algorithm for HIV rapid testing. Questionnaires were used to collect data on sociodemographic characteristics and other risk factors for anaemia.
Results
In total, 1449 people participated (response rate 72.3%). The overall prevalence of anaemia was 20.3 % (95% CI 18.2-22.3%), and this was higher for males (24.1%, 95% CI=20.7-27.7%) than females (17.5%, 95% CI=15.0-20.1%). In males, the prevalence of anaemia increased rapidly with age almost doubling between 50 and 65 years (p-trend<0.001). Unexplained anaemia was responsible for more than half of all cases (59.7%). Anaemia was independently associated with infections including malaria (OR 3.49, 95% CI 1.78-6.82), HIV (OR 2.17, 1.32-3.57) heavy hookworm infection (OR 3.45, 1.73-6.91), low fruit consumption (OR 1.55, 1.05-2.29) and being unmarried (OR 1.37 , 95% CI 1.01-1.89). However, the odds of anaemia were lower among older people with elevated blood pressure (OR 0.47, 95% CI 0.29-0.77).
Conclusion
Anaemia control programmes in Uganda should target older people and should include interventions to treat and control hookworms and educational programs on diets that enhance iron absorption. Clinicians should consider screening older people with HIV or malaria for anaemia. Further studies should be done on unexplained anaemia and serum ferritin levels that predict iron deficiency anaemia in older people.
doi:10.1371/journal.pone.0078394
PMCID: PMC3806814  PMID: 24194926
10.  Cohort Profile: Andhra Pradesh Children and Parents Study (APCAPS) 
The Andhra Pradesh Children and Parents Study (APCAPS) was originally established to study the long-term effects of early-life undernutrition on risk of cardiovascular disease. Its aims were subsequently expanded to include trans-generational influences of other environmental and genetic factors on chronic diseases in rural India. It builds on the Hyderabad Nutrition Trial (HNT) conducted in 1987–90 to compare the effects on birthweight of a protein-calorie supplement for pregnant women and children. The index children of HNT and their mothers were retraced and examined in 2003–05, and the children re-examined as young adults aged 18–21 years in 2009–10. The cohort was expanded to include both parents and siblings of the index children in a recently completed follow-up conducted in 2010–12 (N = ∼6225 out of 10 213 participants). Recruitment of the remaining residents of these 29 villages (N = ∼55 000) in Ranga Reddy district of Andhra Pradesh is now under way. Extensive data on socio-demographic, lifestyle, medical, anthropometric, physiological, vascular and body composition measures, DNA, stored plasma, and assays of lipids and inflammatory markers on APCAPS participants are available. Details of how to access these data are available from the corresponding author.
doi:10.1093/ije/dyt128
PMCID: PMC4190511  PMID: 24019421
11.  Development and validation of anthropometric prediction equations for estimation of lean body mass and appendicular lean soft tissue in Indian men and women 
Journal of Applied Physiology  2013;115(8):1156-1162.
Lean body mass (LBM) and muscle mass remain difficult to quantify in large epidemiological studies due to the unavailability of inexpensive methods. We therefore developed anthropometric prediction equations to estimate the LBM and appendicular lean soft tissue (ALST) using dual-energy X-ray absorptiometry (DXA) as a reference method. Healthy volunteers (n = 2,220; 36% women; age 18-79 yr), representing a wide range of body mass index (14–44 kg/m2), participated in this study. Their LBM, including ALST, was assessed by DXA along with anthropometric measurements. The sample was divided into prediction (60%) and validation (40%) sets. In the prediction set, a number of prediction models were constructed using DXA-measured LBM and ALST estimates as dependent variables and a combination of anthropometric indices as independent variables. These equations were cross-validated in the validation set. Simple equations using age, height, and weight explained >90% variation in the LBM and ALST in both men and women. Additional variables (hip and limb circumferences and sum of skinfold thicknesses) increased the explained variation by 5–8% in the fully adjusted models predicting LBM and ALST. More complex equations using all of the above anthropometric variables could predict the DXA-measured LBM and ALST accurately, as indicated by low standard error of the estimate (LBM: 1.47 kg and 1.63 kg for men and women, respectively), as well as good agreement by Bland-Altman analyses (Bland JM, Altman D. Lancet 1: 307–310, 1986). These equations could be a valuable tool in large epidemiological studies assessing these body compartments in Indians and other population groups with similar body composition.
doi:10.1152/japplphysiol.00777.2013
PMCID: PMC3798815  PMID: 23950165
lean body mass; appendicular lean soft tissue; anthropometry; prediction equation; Indian
12.  Obstetric fistula in Southern Sudan: situational analysis and Key Informant Method to estimate prevalence 
Background
Obstetric fistula is a severe condition which can have devastating consequences for a woman’s life. Despite a considerable literature, very little is known about its prevalence. This project was conducted to carry out a situational analysis of fistula services in South Sudan and to pilot test the Key Informant Method (KIM) to estimate the prevalence of fistula in a region of South Sudan.
Methods
Key stakeholder interviews, document reviews and fistula surgery record reviews were undertaken. A KIM survey was conducted in a district of Western Bahr-el-Ghazal in January 2012. One hundred sixty-six community-based distributors, traditional birth attendants and village midwives were trained as key informants to identify women with fistula in the community. Women identified were subsequently examined by an obstetrician and nurse to verify whether they had a fistula.
Results
There were limited fistula repair services in South Sudan. Approximately 50–80 women per year attend periodic campaigns, with around half having a fistula and receiving a repair. On average a further 5 women a year received fistula repair from hospital services. Ten women with potential fistula were identified via KIM; all confirmed by the obstetrician. Of these, three were from the survey area, which had 8,865 women of reproductive age (15–49 years). This gives a minimal estimated prevalence of at least 30 fistulas per 100,000 women of reproductive age (95% CI 10–100).
Conclusions
Routine fistula repair services available do not meet the population’s needs. The pilot study suggests that KIM can be used to identify women with fistula in the community. Data on fistula are generally poor; the KIM methodology we used in South Sudan yielded a lower fistula prevalence than estimates reported previously in the region.
doi:10.1186/1471-2393-13-64
PMCID: PMC3607911  PMID: 23497241
13.  Prevalence of Age-Related Macular Degeneration in Nakuru, Kenya: A Cross-Sectional Population-Based Study 
PLoS Medicine  2013;10(2):e1001393.
Using digital retinal photography and slit lamp examination in a population-based sample in the Nakuru District of Kenya, Andrew Bastawrous and colleagues determined the prevalence of age-related macular degeneration in adults 50 years and older.
Background
Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population.
Methods and Findings
In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling.
All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading.
Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7.
After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2–1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007.
Conclusions
AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Worldwide, 39 million people are blind, and 246 million people (mainly living in developing countries) have moderate or severe visual impairment. The third leading global cause of blindness (after cataracts and glaucoma) is age-related macular degeneration (AMD). This group of conditions is characterized by lesions in the macular (central) region of the retina, the tissue at the back of the eye that converts light into electrical messages and sends them to the brain. AMD, which affects older people, destroys the sharp central vision that is needed for reading or driving, leaving only dim, blurred images or a black hole at the center of vision. AMD can be diagnosed by examining digital photographs of the retina or by examining the retina directly using a special magnifying lens (slit lamp biomicroscopy). There is no cure for AMD, although injections into the eye of certain drugs, such as bevacizumab, that block the activity of vascular endothelial growth factor can slow the rate of vision loss caused by some forms of AMD.
Why Was This Study Done?
Most investigations of the prevalence (the proportion of a population with a disease) of AMD and of risk factors for AMD have studied people with European or Asian ancestry. Very little is known about AMD in African populations, and the data that are available mainly come from African populations living outside Africa. It is important to know whether AMD is an important cause of visual impairment and blindness in Africa, so that informed decisions can be made about the need for AMD programs in African countries. In this cross-sectional population-based study, the researchers investigate the prevalence of AMD among people aged 50 years or older living in Nakuru District (an ethnically diverse region of Kenya) and look for predictors of AMD in this population. In a cross-sectional population-based study, researchers observe a representative subset of a population at a single time point.
What Did the Researchers Do and Find?
The researchers randomly selected 100 clusters of 50 people aged 50 years or older for their study. Between January 2007 and November 2008, study participants had a comprehensive eye examination and completed a standardized interview that included questions about their age, gender, other demographic details, medical history, and exposure to possible risk factors for AMD. Based on digital retinal images, the prevalences of early and late AMD among the study population were 11.2% and 1.2%, respectively. The prevalences of early and late AMD judged by slit lamp biomicroscopy were 6.7% and 0.7%, respectively. After controlling for age, women had a higher prevalence of both early and late AMD than men. The overall prevalence of AMD rose with age: compared to the youngest age group, the oldest age group had a three-fold higher risk of developing late AMD. Of the people with any grade of AMD, 25.6% had some visual impairment and 2.5% were blind. Overall, 9.9% of the blindness seen in the study was attributable to AMD.
What Do These Findings Mean?
These findings identify AMD as an important cause of visual impairment and blindness in Nakuru District, Kenya. Extrapolation of these findings to the whole of Kenya suggests that 283,900 to 362,800 Kenyans had early AMD and 25,200 to 50,500 had late AMD in 2007. The accuracy of these findings is limited by the inability to obtain digital retinal images from all the participants (often because of electricity failures) and by other aspects of the study design. Moreover, because the methodology used in this study differed from some other studies of AMD, the prevalence of AMD reported here cannot be compared directly to those found in other studies. Nevertheless, these findings have several important implications. In particular, although recent evidence suggests that bevacizumab is likely to be both effective and affordable in Africa, the infrastructure required to deliver an adequate AMD service is currently prohibitively expensive in most African countries. Thus, these findings suggest that it is essential that research is undertaken to support the development of AMD treatment programs that are affordable and deliverable in Africa, and that low vision resources are provided for individuals with vision impairment.
Additional Information
Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001393.
The US National Eye Institute provides detailed information about age-related macular degeneration
The UK National Health Service Choices website also provides information about age-related macular degeneration, including personal stories about the condition
The UK Royal National Institute of Blind People has information on age-related macular degeneration, including a video of a person describing their experiences of the condition
AMD Alliance International provides written and audio information in several languages about age-related macular degeneration, including a large selection of personal stories; the Macular Degeneration Partnership also provides information about age-related macular degeneration, including a simulation of the condition
MedlinePlus has links to additional resources about age-related macular degeneration (in English and Spanish)
doi:10.1371/journal.pmed.1001393
PMCID: PMC3576379  PMID: 23431274
14.  Differences in estimation of creatinine generation between renal function estimating equations in an Indian population: cross-sectional data from the Hyderabad arm of the Indian migration study 
BMC Nephrology  2013;14:30.
Background
Creatinine based formulae for estimating renal function developed in white populations may be less valid in other ethnic groups. We assessed the performance of various estimating formulae in an Indian population.
Methods
917 subjects were recruited from the Hyderabad arm of the Indian Migration Study. Data were collected on comorbidity, serum creatinine and body composition from DXA scans. Renal function was compared using the modified Cockcroft-Gault, MDRD and CKD-EPI formulae. 24-hour creatinine production was derived from each estimate and the agreement with measured muscle mass examined. 24-hour creatinine production estimates were compared to that derived from a formula by Rule incorporating DXA measured muscle mass. Potential systematic biases were examined by age and eGFR. We assessed the association of renal function by each formula with hypertension and self-reported measures of vascular disease.
Results
Mean modified Cockcroft-Gault eCCl was 98.8 ml/min/1.73 m2, MDRD eGFR 91.2 ml/min/1.73 m2 and CKD-EPI eGFR 96.3 ml/min/1.73 m2. MDRD derived 24-hour creatinine production showed the least age-related underestimation compared to the Rule formula. CKD-EPI showed a marked bias at higher eGFRs. All formulae showed similar strength associations with vascular disease and hypertension.
Conclusions
Our analyses support the use of MDRD for estimating renal function in Indian populations. Further work is required to assess the predictive value of formulae for incident disease and complications of CKD.
doi:10.1186/1471-2369-14-30
PMCID: PMC3599554  PMID: 23379609
Creatinine; Ethnicity; Muscle mass; Renal function
15.  Validation of Dual Energy X-Ray Absorptiometry Measures of Abdominal Fat by Comparison with Magnetic Resonance Imaging in an Indian Population 
PLoS ONE  2012;7(12):e51042.
Objective
Abdominal adiposity is an important risk factor for diabetes and cardiovascular disease in Indians. Dual energy X-ray absorptiometry (DXA) can be used to determine abdominal fat depots, being more accessible and less costly than gold standard measures such as magnetic resonance imaging (MRI). DXA has not been fully validated for use in South Asians. Here, we determined the accuracy of DXA for measurement of abdominal fat in an Indian population by comparison with MRI.
Design
146 males and females (age range 18–74, BMI range 15–46 kg/m2) from Hyderabad, India underwent whole body DXA scans on a Hologic Discovery A scanner, from which fat mass in two abdominal regions was calculated, from the L1 to L4 vertebrae (L1L4) and from the L2 to L4 vertebrae (L2L4). Abdominal MRI scans (axial T1-weighted spin echo images) were taken, from which adipose tissue volumes were calculated for the same regions.
Results
Intra-class correlation coefficients between DXA and MRI measures of abdominal fat were high (0.98 for both regions). Although at the level of the individual, differences between DXA and MRI could be large (95% of DXA measures were between 0.8 and 1.4 times MRI measures), at the sample level, DXA only slightly overestimated MRI measures of abdominal fat mass (mean difference in L1L4 region: 2% (95% CI:0%, 5%), mean difference in L2L4 region:4% (95% CI: 1%, 7%)). There was evidence of a proportional bias in the association between DXA and MRI (correlation between difference and mean −0.3), with overestimation by DXA greater in individuals with less abdominal fat (mean bias in leaner half of sample was 6% for L1L4 (95%CI: 2, 11%) and 7% for L2L4 (95% CI:3,12%).
Conclusions
DXA measures of abdominal fat are suitable for use in Indian populations and provide a good indication of abdominal adiposity at the population level.
doi:10.1371/journal.pone.0051042
PMCID: PMC3522679  PMID: 23272086
16.  A comparison of the sensitivity of EQ-5D, SF-6D and TTO utility values to changes in vision and perceived visual function in patients with primary open-angle glaucoma 
BMC Ophthalmology  2012;12:43.
Background
Economic viability of treatments for primary open-angle glaucoma (POAG) should be assessed objectively to prioritise health care interventions. This study aims to identify the methods for eliciting utility values (UVs) most sensitive to differences in visual field and visual functioning in patients with POAG. As a secondary objective, the dimensions of generic health-related and vision-related quality of life most affected by progressive vision loss will be identified.
Methods
A total of 132 POAG patients were recruited. Three sets of utility values (EuroQoL EQ-5D, Short Form SF-6D, Time Trade Off) and a measure of perceived visual functioning from the National Eye Institute Visual Function Questionnaire (VFQ-25) were elicited during face-to-face interviews. The sensitivity of UVs to differences in the binocular visual field, visual acuity and visual functioning measures was analysed using non-parametric statistical methods.
Results
Median utilities were similar across Integrated Visual Field score quartiles for EQ-5D (P = 0.08) whereas SF-6D and Time-Trade-Off UVs significantly decreased (p = 0.01 and p = 0.001, respectively). The VFQ-25 score varied across Integrated Visual Field and binocular visual acuity groups and was associated with all three UVs (P ≤ 0.001); most of its vision-specific sub-scales were associated with the vision markers. The most affected dimension was driving. A relationship with vision markers was found for the physical component of SF-36 and not for any dimension of EQ-5D.
Conclusions
The Time-Trade-Off was more sensitive than EQ-5D and SF-6D to changes in vision and visual functioning associated with glaucoma progression but could not measure quality of life changes in the mildest disease stages.
doi:10.1186/1471-2415-12-43
PMCID: PMC3552875  PMID: 22909264
Glaucoma; Quality of life; Utility values; Cost-utility analysis
17.  Evaluation of the Indian Migration Study Physical Activity Questionnaire (IMS-PAQ): a cross-sectional study 
Background
Socio-cultural differences for country-specific activities are rarely addressed in physical activity questionnaires. We examined the reliability and validity of the Indian Migration Study Physical Activity Questionnaire (IMS-PAQ) in urban and rural groups in India.
Methods
A sub-sample of IMS participants (n = 479) was used to examine short term (≤1 month [n = 158]) and long term (> 1 month [n = 321]) IMS-PAQ reliability for levels of total, sedentary, light and moderate/vigorous activity (MVPA) intensity using intraclass correlation (ICC) and kappa coefficients (k). Criterion validity (n = 157) was examined by comparing the IMS-PAQ to a uniaxial accelerometer (ACC) worn ≥4 days, via Spearman's rank correlations (ρ) and k, using Bland-Altman plots to check for systematic bias. Construct validity (n = 7,000) was established using linear regression, comparing IMS-PAQ against theoretical constructs associated with physical activity (PA): BMI [kg/m2], percent body fat and pulse rate.
Results
IMS-PAQ reliability ranged from ICC 0.42-0.88 and k = 0.37-0.61 (≤1 month) and ICC 0.26 to 0.62; kappa 0.17 to 0.45 (> 1 month). Criterion validity was ρ = 0.18-0.48; k = 0.08-0.34. Light activity was underestimated and MVPA consistently and substantially overestimated for the IMS-PAQ vs. the accelerometer. Criterion validity was moderate for total activity and MVPA. Reliability and validity were comparable for urban and rural participants but lower in women than men. Increasing time spent in total activity or MVPA, and decreasing time in sedentary activity were associated with decreasing BMI, percent body fat and pulse rate, thereby demonstrating construct validity.
Conclusion
IMS-PAQ reliability and validity is similar to comparable self-reported instruments. It is an appropriate tool for ranking PA of individuals in India. Some refinements may be required for sedentary populations and women in India.
doi:10.1186/1479-5868-9-13
PMCID: PMC3296617  PMID: 22321669
Health behaviour; Activity Domains; Low-Middle Income Countries; Reproducibility; Adults; Methodology
18.  Socio-Demographic Patterning of Physical Activity across Migrant Groups in India: Results from the Indian Migration Study 
PLoS ONE  2011;6(10):e24898.
Objective
To investigate the relationship between rural to urban migration and physical activity (PA) in India.
Methods
6,447 (42% women) participants comprising 2077 rural, 2,094 migrants and 2,276 urban were recruited. Total activity (MET hr/day), activity intensity (min/day), PA Level (PAL) television viewing and sleeping (min/day) were estimated and associations with migrant status examined, adjusting for the sib-pair design, age, site, occupation, education, and socio-economic position (SEP).
Results
Total activity was highest in rural men whereas migrant and urban men had broadly similar activity levels (p<0.001). Women showed similar patterns, but slightly lower levels of total activity. Sedentary behaviour and television viewing were lower in rural residents and similar in migrant and urban groups. Sleep duration was highest in the rural group and lowest in urban non-migrants. Migrant men had considerably lower odds of being in the highest quartile of total activity than rural men, a finding that persisted after adjustment for age, SEP and education (OR 0.53, 95% CI 0.37, 0.74). For women, odds ratios attenuated and associations were removed after adjusting for age, SEP and education.
Conclusion
Our findings suggest that migrants have already acquired PA levels that closely resemble long-term urban residents. Effective public health interventions to increase PA are needed.
doi:10.1371/journal.pone.0024898
PMCID: PMC3194815  PMID: 22022366
19.  Does Cataract Surgery Alleviate Poverty? Evidence from a Multi-Centre Intervention Study Conducted in Kenya, the Philippines and Bangladesh 
PLoS ONE  2010;5(11):e15431.
Background
Poverty and blindness are believed to be intimately linked, but empirical data supporting this purported relationship are sparse. The objective of this study is to assess whether there is a reduction in poverty after cataract surgery among visually impaired cases.
Methodology/Principal Findings
A multi-centre intervention study was conducted in three countries (Kenya, Philippines, Bangladesh). Poverty data (household per capita expenditure – PCE, asset ownership and self-rated wealth) were collected from cases aged ≥50 years who were visually impaired due to cataract (visual acuity<6/24 in the better eye) and age-sex matched controls with normal vision. Cases were offered free/subsidised cataract surgery. Approximately one year later participants were re-interviewed about poverty. 466 cases and 436 controls were examined at both baseline and follow-up (Follow up rate: 78% for cases, 81% for controls), of which 263 cases had undergone cataract surgery (“operated cases”). At baseline, operated cases were poorer compared to controls in terms of PCE (Kenya: $22 versus £35 p = 0.02, Bangladesh: $16 vs $24 p = 0.004, Philippines: $24 vs 32 p = 0.0007), assets and self-rated wealth. By follow-up PCE had increased significantly among operated cases in each of the three settings to the level of controls (Kenya: $30 versus £36 p = 0.49, Bangladesh: $23 vs $23 p = 0.20, Philippines: $45 vs $36 p = 0.68). There were smaller increases in self-rated wealth and no changes in assets. Changes in PCE were apparent in different socio-demographic and ocular groups. The largest PCE increases were apparent among the cases that were poorest at baseline.
Conclusions/Significance
This study showed that cataract surgery can contribute to poverty alleviation, particularly among the most vulnerable members of society. This study highlights the need for increased provision of cataract surgery to poor people and shows that a focus on blindness may help to alleviate poverty and achieve the Millennium Development Goals.
doi:10.1371/journal.pone.0015431
PMCID: PMC2976760  PMID: 21085697
20.  Prevalence and causes of blindness and visual impairment in Limbe urban area, South West Province, Cameroon 
The British Journal of Ophthalmology  2007;91(11):1435-1439.
Aim
To conduct a rapid assessment of cataract surgical services to estimate the prevalence and causes of blindness and visual impairment in members of the population aged ⩾40 years in the Limbe urban area, Cameroon.
Methods
Clusters of 50 people aged ⩾40 years were sampled with probability proportionate to size. Compact segment sampling was used to select households within clusters. All eligible people had their visual acuity (VA) measured by an ophthalmic nurse. An ophthalmologist examined people with VA<6/18.
Results
2215 people were examined (response rate = 92.3%). The prevalence of bilateral blindness was 1.1% (95% CI: 0.7–1.5%), 0.3% (0.1–0.6%) for severe visual impairment and 3.0% (2.0–4.0%) for visual impairment. Posterior‐segment disease was the leading cause of blindness (29%), followed by cataracts (21%) and optic atrophy (21%). Cataracts were the most common cause of severe visual impairment (43%) and visual impairment (48%). Most cases of blindness (50%), severe visual impairment (57%) and visual impairment (78%) were avoidable (that is, they were caused by cataracts, refractive error, corneal scar, onchocerciasis or phthisis/no globe). The cataract surgical coverage was relatively high, although 57% of eyes operated upon had a poor outcome (presenting VA<6/60).
Conclusions
Although the prevalence of blindness was relatively low, most of the cases were avoidable. The implementation of an effective eye‐care programme remains a priority in the Limbe urban area.
doi:10.1136/bjo.2007.115840
PMCID: PMC2095403  PMID: 17389739
Blindness; Cameroon; survey; cataract; prevalence; urban
21.  Clint's favourite question 
BMJ : British Medical Journal  2007;335(7624):818.
doi:10.1136/bmj.39290.613206.DE
PMCID: PMC2034726
22.  Urbanization, ethnicity and cardiovascular risk in a population in transition in Nakuru, Kenya: a population-based survey 
BMC Public Health  2010;10:569.
Background
Cardiovascular disease (CVD) is the leading cause of death among older people in Africa. This study aimed to investigate the relationship of urbanization and ethnicity with CVD risk markers in Kenya.
Methods
A cross-sectional population-based survey was carried out in Nakuru Kenya in 2007-2008. 100 clusters of 50 people aged ≥50 years were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants were interviewed by nurses to collect socio-demographic and lifestyle information. Nurses measured blood pressure, height, weight and waist and hip circumference. A random finger-prick blood sample was taken to measure glucose and cholesterol levels.
Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg, or diastolic blood pressure (DBP) ≥90 mm Hg or current use of antihypertensive medication; Diabetes as reported current medication or diet control for diabetes or random blood glucose level ≥11.1 mmol/L; High cholesterol as random blood cholesterol level ≥5.2 mmol/L; and Obesity as Body Mass Index (BMI)≥30 kg/m2.
Results
5010 eligible subjects were selected, of whom 4396 (88%) were examined. There was a high prevalence of hypertension (50.1%, 47.5-52.6%), obesity (13.0%, 11.7-14.5%), diabetes (6.6%, 5.6-7.7%) and high cholesterol (21.1%, 18.6-23.9). Hypertension, diabetes and obesity were more common in urban compared to rural groups and the elevated prevalence generally persisted after adjustment for socio-demographic, lifestyle, obesity and cardiovascular risk markers. There was also a higher prevalence of hypertension, obesity, diabetes and high cholesterol among Kikuyus compared to Kalenjins, even after multivariate adjustment. CVD risk markers were clustered both across the district and within individuals. Few people received treatment for hypertension (15%), while the majority of cases with diabetes received treatment (68%).
Conclusions
CVD risk markers are common in Kenya, particularly in urban areas. Exploring differences in CVD risk markers between ethnic groups may help to elucidate the epidemiology of these conditions.
doi:10.1186/1471-2458-10-569
PMCID: PMC2956724  PMID: 20860807
23.  Rapid Assessment of Avoidable Blindness in the Occupied Palestinian Territories 
PLoS ONE  2010;5(7):e11854.
Background
There are no recent data on the prevalence and causes of blindness in the Occupied Palestinian Territories. The aim of our study was to estimate the prevalence and causes of blindness and visual impairment in the population aged 50 years and above in the Occupied Palestinian Territories using the Rapid Assessment of Avoidable Blindness (RAAB) survey method.
Methods and Findings
Clusters of 40 people who were 50 years and above were selected with probability proportionate to size using a multistage cluster random sampling method. Participants received a comprehensive ophthalmic examination in their homes, including visual acuity testing by one of three experienced ophthalmologists. The principal cause for visual loss was determined by an experienced ophthalmologist using portable diagnostic instruments. Information about previous cataract surgery, satisfaction with surgery and barriers to cataract surgery were collected. The prevalence of self-reported diabetes was also determined. The prevalence of bilateral blindness (VA<3/60 in the better eye with available correction) was 3.4% (95% CI: 2.7–4.0), 2.0% (95% CI: 1.4–2.5) for severe visual impairment (VA≥3/60 and <6/60), and 7.4% (95% CI: 6.4–8.3) for visual impairment (VA≥6/60 and <6/18). Avoidable causes (i.e. cataract, refractive error, aphakia, surgical complications, corneal scarring and phthysis) accounted for 80.0% of bilateral blindness, severe visual impairment (70.7%) and visual impairment (86.2%). Cataract was the main cause of blindness (55.0%). The prevalence of blindness was higher in Gaza (4.9%, 95% CI: 3.7–6.1%) than in the West Bank (2.5%, 95% CI: 1.9–3.1%) and among women (4.3%,95% CI: 3.3–5.2%) compared to men (2.2%,95%CI:1.5–2.9%). Among people who had undergone cataract surgery in the past, only 54.5% of eyes obtained a good outcome (VA≥6/18), 23.2% had a borderline outcome (VA<6/18 and ≥6/60) and 22.3% had a poor outcome (VA<6/60) with available correction. The prevalence of self-reported diabetes mellitus in ≥50 year age group was 26.4% (95% CI: 24.9–27.9).
Conclusions
The prevalence of blindness suggests that significant numbers of people in the Occupied Palestinian Territories exist who do not access eye care - predominantly women and those residing in Gaza. Programmes need to focus on maximizing the use of current services by these excluded groups.
doi:10.1371/journal.pone.0011854
PMCID: PMC2912325  PMID: 20686616
24.  Cataract visual impairment and quality of life in a Kenyan population 
Aims
To evaluate the World Health Organization Prevention of Blindness and Deafness 20‐item Visual Functioning Questionnaire (WHO/PBD VF20), a vision‐related quality of life scale, and to describe the relationship between cataract visual impairment and vision‐ and generic health‐related quality of life, in people ⩾50 years of age in Nakuru district, Kenya.
Methods
The WHO/PBD VF20 was pilot tested and modified. 196 patients with visual impairment from cataract and 128 population‐based controls without visual impairment from cataract were identified through a district‐wide survey. Additional cases were identified through case finding. Vision‐ and health‐related quality of life were assessed using the WHO/PBD VF20 scale and EuroQol generic health index (European Quality of Life Questionnaire (EQ‐5D)), respectively. WHO/PBD VF20 was evaluated using standard psychometric tests, including factor analysis to determine item grouping for summary scores.
Results
The modified WHO/PBD VF20 demonstrated good psychometric properties. Two subscales (general functioning and psychosocial) and one overall eyesight‐rating item were appropriate for these data. Increased severity of visual impairment in cases was associated with worsening general functioning, psychosocial and overall eyesight scores (p for trend <0.001). Cases were more likely to report problems with EQ‐5D descriptive dimensions than controls (p<0.001), and, among cases, increased severity of visual impairment was associated with worsening self‐rated health score.
Conclusion
The modified WHO/PBD VF20 is a valid and reliable scale to assess vision‐related quality of life associated with cataract visual impairment in this Kenyan population. The association between health‐related quality of life and visual impairment reflects the wider implications of cataract for health and well‐being, beyond visual acuity alone.
doi:10.1136/bjo.2006.110973
PMCID: PMC1955630  PMID: 17272387
25.  The Impact of Cataract Surgery on Activities and Time-Use: Results from a Longitudinal Study in Kenya, Bangladesh and the Philippines 
PLoS ONE  2010;5(6):e10913.
Background
Cataract is the leading cause of blindness in the world, and blindness from cataract is particularly common in low-income countries. The aim of this study is to explore the impact of cataract surgery on daily activities and time-use in Kenya, Bangladesh and the Philippines.
Methods/Principal Findings
A multi-centre intervention study was conducted in three countries. Time-use data were collected through interview from cases aged ≥50 years with visually impairing cataract (VA <6/24) and age- and gender-matched controls with normal vision (VA≥6/18). Cases were offered free/subsidized cataract surgery. Approximately one year later participants were re-interviewed about time-use. At baseline across the three countries there were 651 cases and 571 controls. Fifty-five percent of cases accepted surgery. Response rate at follow up was 84% (303 out of 361) for operated cases, and 80% (459 out of 571) for controls. At baseline, cases were less likely to carry out and spent less time on productive activities (paid and non-paid work) and spent more time in “inactivity” compared to controls. Approximately one year after cataract surgery, operated cases were more likely to undertake productive activities compared to baseline (Kenya from 55% to 88%; Bangladesh 60% to 95% and Philippines 81% to 94%, p<0.001) and mean time spent on productive activities increased by one-two hours in each setting (p<0.001). Time spent in “inactivity” in Kenya and Bangladesh decreased by approximately two hours (p<0.001). Frequency of reported assistance with activities was more than halved in each setting (p<0.001).
Conclusions/Significance
The empirical evidence provided by this study of increased time spent on productive activities, reduced time in inactivity and reduced assistance following cataract surgery among older adults in low-income settings has positive implications for well-being and inclusion, and supports arguments of economic benefit at the household level from cataract surgery.
doi:10.1371/journal.pone.0010913
PMCID: PMC2879361  PMID: 20531957

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