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1.  Population prevalence of asthma and its determinants based on European Community Respiratory Health Survey in the United Arab Emirates 
No population study has explored the population distribution of adult asthma in the United Arab Emirates (UAE). The objective is to estimate asthma prevalence in general population in UAE.
Using standard European Community Respiratory Health Survey (ECRHS) questionnaires and tools, this is a cross-sectional assessment of a random sample of the population in established quotas of the seven Emirates in the UAE. We surveyed 1,220 participants, of which 63.2% were male, and 20.1% were UAE Nationals, with a mean (SD) age of 32.9 (14.1) years.
Prevalence of individual respiratory symptoms from the ECRHS screening questionnaire in all participants were generally ranging 8 - 10%, while participants 20-44 years presented lower prevalence in all symptoms (p < 0.05). The expected male:female ratio of reported wheezing and asthma attacks and its treatment by age was not observed. Participating women reported more individual symptoms than men. Overall, there were 15.4% (95% C.I. 13.5 - 17.5) participants who fulfilled our screening criteria for asthma, while for consistency with ECRHS, there were 12.1% (95% C.I. 10.4 - 14.1) participants who fulfilled the ECRHS asthma definition, being 9.8% (95% C.I. 7.8 - 12.2) of those 20-44 years, that is 8.6% of male and 11.8% of female young adults participating.
We conclude that asthma is common in the UAE, and gender differences are not observed in reported asthma symptoms in young adults. This being the first population based study exploring the prevalence of asthma and its determinants in the United Arab Emirates based on the ECRHS.
PMCID: PMC3306751  PMID: 22340199
2.  Longterm follow-up in European respiratory health studies – patterns and implications 
Selection bias is a systematic error in epidemiologic studies that may seriously distort true measures of associations between exposure and disease. Observational studies are highly susceptible to selection bias, and researchers should therefore always examine to what extent selection bias may be present in their material and what characterizes the bias in their material. In the present study we examined long-term participation and consequences of loss to follow-up in the studies Respiratory Health in Northern Europe (RHINE), Italian centers of European Community Respiratory Health Survey (I-ECRHS), and the Italian Study on Asthma in Young Adults (ISAYA).
Logistic regression identified predictors for follow-up participation. Baseline prevalence of 9 respiratory symptoms (asthma attack, asthma medication, combined variable with asthma attack and/or asthma medication, wheeze, rhinitis, wheeze with dyspnea, wheeze without cold, waking with chest tightness, waking with dyspnea) and 9 exposure-outcome associations (predictors sex, age and smoking; outcomes wheeze, asthma and rhinitis) were compared between all baseline participants and long-term participants. Bias was measured as ratios of relative frequencies and ratios of odds ratios (ROR).
Follow-up response rates after 10 years were 75% in RHINE, 64% in I-ECRHS and 53% in ISAYA. After 20 years of follow-up, response was 53% in RHINE and 49% in I-ECRHS. Female sex predicted long-term participation (in RHINE OR (95% CI) 1.30(1.22, 1.38); in I-ECRHS 1.29 (1.11, 1.50); and in ISAYA 1.42 (1.25, 1.61)), as did increasing age. Baseline prevalence of respiratory symptoms were lower among long-term participants (relative deviations compared to total baseline population 0-15% (RHINE), 0-48% (I-ECRHS), 3-20% (ISAYA)), except rhinitis which had a slightly higher prevalence. Most exposure-outcome associations did not differ between long-term participants and all baseline participants, except lower OR for rhinitis among ISAYA long-term participating smokers (relative deviation 17% (smokers) and 44% (10–20 pack years)).
We found comparable patterns of long-term participation and loss to follow-up in RHINE, I-ECRHS and ISAYA. Baseline prevalence estimates for long-term participants were slightly lower than for the total baseline population, while exposure-outcome associations were mainly unchanged by loss to follow-up.
PMCID: PMC4021078  PMID: 24739530
3.  Gender differences in respiratory symptoms in 19-year-old adults born preterm 
Respiratory Research  2005;6(1):117.
To study the prevalence of respiratory and atopic symptoms in (young) adults born prematurely, differences between those who did and did not develop Bronchopulmonary Disease (BPD) at neonatal age and differences in respiratory health between males and females.
Design: Prospective cohort study.
Setting: Nation wide follow-up study, the Netherlands.
Participants: 690 adults (19 year old) born with a gestational age below 32 completed weeks and/or with a birth weight less than 1500 g. Controls were Dutch participants of the European Community Respiratory Health Survey (ECRHS).
Main outcome measures: Presence of wheeze, shortness of breath, asthma, hay fever and eczema using the ECRHS-questionnaire
The prevalence of doctor-diagnosed asthma was significantly higher in the ex-preterms than in the general population, whereas eczema and hay fever were significant lower. Women reported more symptoms than men. Preterm women vs controls: asthma 13% vs 5% (p < 0.001); hay fever 8% vs 20% (p < 0.001); eczema 10% vs 42% (p < 0.001). Preterm men vs controls: asthma 9% vs 4% (p = 0.007); hay fever 8% vs 17% (p = 0.005); eczema 9% vs 31% (p < 0.001) Preterm women reported more wheeze and shortness of breath during exercise (sob) than controls: wheeze 30% vs 22% (p = 0.009); sob 27% vs 16% (p < 0.001); 19-year-old women with BPD reported a higher prevalence of doctor diagnosed asthma compared to controls (24% vs 5% p < 0.001) and shortness of breath during exercise (43% vs 16% p = 0.008). The prevalence of reported symptoms by men with BPD were comparable with the controls.
Our large follow-up study shows a higher prevalence of asthma, wheeze and shortness of breath in the prematurely born young adults. 19-year-old women reported more respiratory symptoms than men. Compared to the general population atopic diseases as hay fever and eczema were reported less often.
PMCID: PMC1283982  PMID: 16223446
4.  Evolution of Asthma Severity in a Cohort of Young Adults: Is There Any Gender Difference? 
PLoS ONE  2009;4(9):e7146.
Little is known about the distribution of asthma severity in men and women in the general population. The objective of our study was to describe asthma severity and change in severity according to gender in a cohort of adult asthmatics
Subjects with asthma were identified from random samples of the 22 to 44 year-olds from the general population, screened for asthma from 1991 to 1993 in 48 centers from 22 countries and followed-up during 1998–2002, as part of the European Community Respiratory Health Survey (ECRHS). All participants to follow-up with current asthma at baseline were eligible for the analysis. To assess change over the follow-up, asthma severity at the two surveys was defined using standardized data on respiratory symptoms, lung function and medication according to the Global Initiative for Asthma (GINA) Guidelines. Another quantitative score (Ronchetti) further considering hospitalizations was also analysed.
The study included 685 subjects with asthma followed-up over a mean period of 8.65 yr (min 4.3-max 11.7). At baseline, asthma severity according to GINA was distributed as intermittent: 40.7%, 31.7% as mild persistent, 14% as moderate persistent, and 13.5% as severe persistent. Using the Ronchetti score derived classification, the distribution of asthma severity was 58% mild, (intermittent and mild persistent), 25.8% moderate, and 15.4% severe. Whatever the classification, there was no significant difference in the severity distribution between men and women. There was also no gender difference in the severity distribution among incident cases which developed asthma between the two surveys. Men with moderate-to-severe asthma at baseline were more likely than women to have moderate-to-severe asthma at follow-up. Using GINA, 69.2% of men vs. 53.1% of women (p = 0.09) with moderate-to-severe asthma at baseline were still moderate-to-severe at follow-up. Using Ronchetti score, 53.3% of men vs. 36.2% of women (p = 0.03) with moderate-to-severe asthma at baseline were still moderate-to-severe at follow-up.
There was no gender difference in asthma severity at the two surveys. However, our findings suggest that asthma severity might be less stable in women than in men.
PMCID: PMC2745579  PMID: 19779616
5.  Asthma and allergies in Jamaican children aged 2–17 years: a cross-sectional prevalence survey 
BMJ Open  2012;2(4):e001132.
To determine the prevalence and severity of asthma and allergies as well as risk factors for asthma among Jamaican children aged 2–17 years.
A cross-sectional, community-based prevalence survey using the International Study of Asthma and Allergies in Childhood questionnaire. The authors selected a representative sample of 2017 children using stratified, multistage cluster sampling design using enumeration districts as primary sampling units.
Jamaica, a Caribbean island with a total population of approximately 2.6 million, geographically divided into 14 parishes.
Children aged 2–17 years, who were resident in private households. Institutionalised children such as those in boarding schools and hospitals were excluded from the survey.
Primary and secondary outcome measures
The prevalence and severity of asthma and allergy symptoms, doctor-diagnosed asthma and risk factors for asthma.
Almost a fifth (19.6%) of Jamaican children aged 2–17 years had current wheeze, while 16.7% had self-reported doctor-diagnosed asthma. Both were more common among males than among females. The prevalence of rhinitis, hay fever and eczema among children was 24.5%, 25% and 17.3%, respectively. Current wheeze was more common among children with rhinitis in the last 12 months (44.3% vs 12.6%, p<0.001), hay fever (36.8% vs 13.8%, p<0.001) and eczema (34.1% vs 16.4%, p<0.001). Independent risk factors for current wheeze (ORs, 95% CI) were chest infections in the first year of life 4.83 (3.00 to 7.77), parental asthma 4.19 (2.8 to 6.08), rhinitis in the last 12 months 6.92 (5.16 to 9.29), hay fever 4.82 (3.62 to 6.41), moulds in the home 2.25 (1.16 to 4.45), cat in the home 2.44 (1.66 to 3.58) and dog in the home 1.81 (1.18 to 2.78).
The prevalence of asthma and allergies in Jamaican children is high. Significant risk factors for asthma include chest infections in the first year of life, a history of asthma in the family, allergies, moulds and pets in the home.
Article summary
Article focus
The prevalence of asthma and allergies in both developed and developing countries is continuing to rise.
In some Caribbean countries, asthma is a public health problem associated with high economic costs.
This study determined the prevalence of asthma, allergy symptoms and associated risk factors.
Key messages
We demonstrated that the prevalence of asthma and allergy symptoms among Jamaican children aged 2–17 years is high.
Both the prevalence and severity of asthma symptoms are comparable to that reported among children in high-income countries.
Current wheeze and doctor-diagnosed asthma were more common in males and in children with allergies.
A history of asthma in the family, chest infections in the first year of life, allergies, exposure to moulds and pets in the home were associated with significant risk for asthma.
Identifying children at high risk for asthma and controlling modifiable risk factors is important in reducing the prevalence and morbidity related to asthma.
Strengths and limitations of this study
This is the first national study on asthma and allergies in Jamaica using a nationally representative sample of children with a response rate of 80%.
We used a modified ISAAC protocol in which sampling was done by household rather than by school. Using a population-based sampling strategy; we sampled one child and one adult per household. This approach enabled us to obtain national prevalence estimates for both adults and children in one survey at a reduced cost.
Limitations of this study include the fact that the prevalence of asthma and allergies was based solely on self-reports, no objective measures were done. Also in younger children, caregivers responded to questionnaires.
PMCID: PMC3400072  PMID: 22798254
6.  Occupational risk factors for asthma among nurses and related healthcare professionals in an international study 
The authors examined the relations between self‐reported work tasks, use of cleaning products and latex glove use with new‐onset asthma among nurses and other healthcare workers in the European Community Respiratory Health Survey (ECRHS II).
In a random population sample of adults from 22 European sites, 332 participants reported working in nursing and other related healthcare jobs during the nine‐year ECRHS II follow‐up period and responded to a supplemental questionnaire about their principal work settings, occupational tasks, products used at work and respiratory symptoms. Poisson regression models with robust error variances were used to compare the risk of new‐onset asthma among healthcare workers with each exposure to that of respondents who reported professional or administrative occupations during the entire follow‐up period (n = 2481).
Twenty (6%) healthcare workers and 131 (5%) members of the referent population reported new‐onset asthma. Compared to the referent group, the authors observed increased risks among hospital technicians (RR 4.63; 95% CI 1.87 to 11.5) and among those using ammonia and/or bleach at work (RR 2.16; 95% CI 1.03 to 4.53).
In the ECRHS II cohort, hospital technicians and other healthcare workers experience increased risks of new‐onset current asthma, possibly due to specific products used at work.
PMCID: PMC2078479  PMID: 17332135
7.  Prevalence of asthma among Chinese adolescents living in Canada and in China 
Studies of the prevalence of asthma among migrating populations may help in identifying environmental risk factors.
We analyzed data from Vancouver, Canada, and from Guangzhou, Beijing and Hong Kong, China, collected during phase 3 of the International Study of Asthma and Allergies in Childhood. We subdivided the Vancouver adolescents according to whether they were Chinese immigrants to Canada, Canadian-born Chinese or Canadian-born non-Chinese. We compared the prevalence of asthma and wheezing among Chinese adolescents born in Canada, Chinese adolescents who had immigrated to Canada and Chinese adolescents living in China.
Of 7794 Chinese adolescents who met the inclusion criteria, 3058 were from Guangzhou, 2824 were from Beijing, and 1912 were from Hong Kong. Of 2235 adolescents in Vancouver, Canada, 475 were Chinese immigrants, 617 were Canadian-born Chinese, and 1143 were Canadian-born non-Chinese. The prevalence of current wheezing among boys ranged from 5.9% in Guangzhou to 11.2% in Canadian-born Chinese adolescents. For girls, the range was 4.3% in Guangzhou to 9.8% in Canadian-born Chinese adolescents. The prevalence of ever having had asthma ranged from 6.6% to 16.6% for boys and from 2.9% to 15.0% for girls. Prevalence gradients persisted after adjustment for other environmental variables (odds ratios for ever having had asthma among Canadian-born Chinese compared with native Chinese in Guangzhou: 2.72 [95% confidence interval 1.75–4.23] for boys and 5.50 [95% confidence interval 3.21–9.44] for girls; p < 0.001 for both). Among Chinese adolescents living in Vancouver, the prevalence of ever wheezing increased with duration of residence, from 14.5% among those living in Canada for less than 7 years to 20.9% among those living their entire life in Canada. The same pattern was observed for the prevalence of ever having had asthma, from 7.7% to 15.9%.
Asthma symptoms in Chinese adolescents were lowest among residents of mainland China, were greater for those in Hong Kong and those who had immigrated to Canada, and were highest among those born in Canada. These findings suggest that environmental factors and duration of exposure influence asthma prevalence.
PMCID: PMC2582762  PMID: 19015564
8.  A population-based study of asthma, quality of life, and occupation among elderly Hispanic and non-Hispanic whites: a cross-sectional investigation 
BMC Public Health  2005;5:97.
The U.S. population is aging and is expected to double by the year 2030. The current study evaluated the prevalence of asthma and its correlates in the elderly Hispanic and non-Hispanic white population.
Data from a sample of 3021 Hispanics and non-Hispanic White subjects, 65 years and older, interviewed as part of an ongoing cross-sectional study of the elderly in west Texas, were analyzed. The outcome variable was categorized into: no asthma (reference category), current asthma, and probable asthma. Polytomous logistic regression analysis was used to assess the relationship between the outcome variable and various socio-demographic measures, self-rated health, asthma symptoms, quality of life measures (SF-12), and various occupations.
The estimated prevalence of current asthma and probable asthma were 6.3% (95%CI: 5.3–7.2) and 9.0% (95%CI: 7.8–10.1) respectively. The majority of subjects with current asthma (Mean SF-12 score 35.8, 95%CI: 34.2–37.4) or probable asthma (35.3, 34.0–36.6) had significantly worse physical health-related quality of life as compared to subjects without asthma (42.6, 42.1–43.1). In multiple logistic regression analyses, women had a 1.64 times greater odds of current asthma (95%CI: 1.12–2.38) as compared to men. Hay fever was a strong predictor of both current and probable asthma. The odds of current asthma were 1.78 times (95%CI: 1.24–2.55) greater among past smokers; whereas the odds of probable asthma were 2.73 times (95%CI: 1.77–4.21) greater among current smokers as compared to non-smokers. Similarly fair/poor self rated health and complaints of severe pain were independently associated with current and probable asthma. The odds of current and probable asthma were almost two fold greater for obesity. When stratified by gender, the odds were significantly greater among females (p-value for interaction term = 0.038). The odds of current asthma were significantly greater for farm-related occupations (adjusted OR = 2.09, 95%CI: 1.00–4.39); whereas the odds were significantly lower among those who reported teaching as their longest held occupation (adjusted OR = 0.36, 95%CI = 0.18–0.74).
This study found that asthma is a common medical condition in the elderly and it significantly impacts quality of life and general health status. Results support adopting an integrated approach in identifying and controlling asthma in this population.
PMCID: PMC1249583  PMID: 16176583
9.  The prevalence of asthma in children of elementary school age in Western New York 
To determine the prevalence of caregiver-reported asthma in children 4 to 13 years old in metropolitan western New York State, surveys were conducted during 1997–1999 in the Buffalo, Niagara Falls, Iroquois, and Gowanda school systems. Questionaires (3,889) were sent to the homes of elementary school children in nine schools in western New York. The caregivers were asked to complete a 13-item questionnaire for the child. Of the questionnaires, 60.5% (2,353/3,889) were completed.
Of all children, 18% had physician-diagnosed asthma. Of children diagnosed with asthma, 86% were taking medication. Symptoms were consistent with suspected undiagnosed asthma for 13% of the children. Buffalo had the highest rate of diagnosed asthma (20%) for the age group. Gowanda had a prevalence of 18%, Iroquois 16%, and Niagara Falls 15%. Variations were observed in asthma prevalence rates among different racial/ ethnic groups. In general, boys had a significantly (P=.001) increased odds of being asthmatic compared with girls. Overall, African-Americans and Hispanic/Latino children had significantly (P=.012 andP=.005, respectively) higher asthma prevalence rates, two to five times those of their Caucasian peers. In Gowanda, the prevalence of diagnosed asthma among Native American children was 23%, compared to 15% among Caucasian children. Of diagnosed Native American children, 71% were female. In Gowanda, a significant association (P=.007) of asthma among children in split-grade classes was observed compared to nonsplit grades. Of Native American children in split grades, 60% were diagnosed asthmatics. These observations reveal a high prevalence of asthma in the age group of 4 to 13 year olds in western New York. Local variations in potential triggers of asthma need to be considered when advising asthmatics. The results suggest that some grades have a disproportionate amount of children with asthma. The implications of asthma for children's early education need to be examined further.
PMCID: PMC3456761  PMID: 11194314
Fish processing is a common economic activity in Southern Africa. The aim of this study was to determine the prevalence and host determinants of allergic symptoms, allergic sensitization, bronchial hyper-responsiveness and asthma among workers processing saltwater fish.
A cross-sectional study was conducted on 594 currently employed workers in two processing plants involved in pilchard canning and fishmeal processing. A modified European Community Respiratory Health Survey (ECRHS) questionnaire was used. Skin prick tests (SPT) used extracts of common airborne allergens, fresh fish (pilchard, anchovy, maasbanker, mackerel, red eye) and fishmeal. Spirometry and methacholine challenge tests (tidal breathing method) used ATS guidelines.
Work-related ocular-nasal symptoms (26%) were more common than asthma symptoms (16%). The prevalence of atopy was 36%, while 7% were sensitized to fish species and 26% had NSBH (PC20 ≤ 8 mg/ml or ≥12% increase in FEV1 post bronchodilator). The prevalence of probable occupational asthma was 1.8% and fish allergic rhino-conjunctivitis 2.6%. Women were more likely to report work-related asthma symptoms (OR=1.94) and have NSBH (OR=3.09), while men were more likely to be sensitized to fish (OR=2.06) and have airway obstruction (OR=4.17). Atopy (OR=3.16) and current smoking (OR=2.37), but not habitual seafood consumption were associated with sensitization to fish.
Based on comparison with previous published studies, the prevalence of occupational asthma to salt water fish is lower than due to shellfish. The gendered distribution of work and exposures in fish processing operations together with atopy and cigarette smoking are important determinants of occupational allergy and asthma.
PMCID: PMC2834300  PMID: 18726880
fish processing; occupational allergy; work-related asthma; atopy; smoking; gender
11.  Opposing trends in the prevalence of health professional-diagnosed asthma by sex: A Canadian National Population Health Survey study 
The prevalence of asthma is on the rise worldwide, with large variations in prevalence existing between and within countries. Little is known regarding the variation in asthma prevalence in adults living in rural and urban settings.
Using questionnaire data from the Canadian National Population Health Survey, the prevalence of asthma at four time periods (1994/1995 [cycle 1], 1996/1997 [cycle 2], 1998/1999 [cycle 3] and 2000/2001 [cycle 4]) was compared between rural and urban populations stratified by sex, smoking status and age group. Asthma was defined as a positive response to the question: “Do you have asthma diagnosed by a health professional?”
To account for the complexity of the survey design, the bootstrap method was used to calculate prevalences and 95% CIs.
Overall, the prevalence of asthma increased from 7.3% (cycle 1) to 7.5% (cycle 4). After stratifying by sex, the asthma prevalence decreased among men, but in women, there was a steady increase. Asthma prevalence increased for both the rural population and the urban population. After stratifying each cycle by sex and location (rural or urban), both rural and urban men showed a decrease in asthma prevalence. On dividing according to age groups (0 to 14 years, 15 to 34 years, 35 to 64 years, and 65 years and older), the prevalence of asthma was greatest in the 15- to 34-year age group of urban and rural women.
Asthma prevalence increased among rural and urban women. The prevalence of asthma was highest among female smokers and male nonsmokers when stratified by smoking status. Based on these findings, the rate of increase in asthma prevalence is different for men and women.
PMCID: PMC2677939  PMID: 18437257
Asthma prevalence; Bootstrap; Complex survey design; Rural; Smoking; Urban; Women
12.  Increase in diagnosed asthma but not in symptoms in the European Community Respiratory Health Survey 
Thorax  2004;59(8):646-651.
Background: Information on the epidemiology of asthma in relation to age is limited and hampered by reporting error. To determine the change in the prevalence of asthma with age in young adults we analysed longitudinal data from the European Community Respiratory Health Survey.
Methods: A self-administered questionnaire was completed by 11 168 randomly selected subjects in 14 countries in 1991–3 when they were aged 20–44 years and 5–11 years later from 1998 to 2003. Generalised estimating equations were used to estimate net change in wheeze, nocturnal tightness in chest, shortness of breath, coughing, asthma attacks in the last 12 months, current medication, "diagnosed" asthma, and nasal allergies.
Results: Expressed as change in status per 10 years of follow up, subjects reporting asthma attacks in the previous 12 months increased by 0.8% of the population (95% CI 0.2 to 1.4) and asthma medication by 2.1% (95% CI 1.6 to 2.6), while no statistically significant net change was found in reported symptoms. Reported nasal allergies increased, especially in the youngest age group.
Conclusions: As this cohort of young adults has aged, there has been an increase in the proportion treated for asthma but not in the proportion of those reporting symptoms suggestive of asthma. Either increased use of effective treatments has led to decreased morbidity among asthmatic subjects or those with mild disease have become more likely to label themselves as asthmatic.
PMCID: PMC1747094  PMID: 15282382
13.  Use of inhaled medications and urgent care services. Study of Canadian asthma patients. 
Canadian Family Physician  1999;45:1707-1713.
OBJECTIVE: To determine asthma patients' patterns of disease and knowledge of asthma. DESIGN: Telephone survey of patients with diagnosed asthma. SETTING: Residences in 10 Canadian provinces. PARTICIPANTS: Patients with asthma diagnosed by a doctor: 829 men and women with a mean age of 38 +/- 7 years. MAIN OUTCOME MEASURES: Classes of asthma medications, patterns of use, frequency and severity of asthma symptoms use of emergency departments and urgent medical services, participation in asthma education programs, presence of environmental triggers, and knowledge of asthma pathophysiology and treatment. RESULTS: Four hundred fifty-six patients (55%) reported daily symptoms of asthma; 431 patients (52%) used inhaled beta 2-agonists daily. Only 340 patients (41%) used inhaled corticosteroids (IC), and many used them irregularly. A total of 579 (72%) respondents reported no unscheduled visits to a family physician for worsening asthma, but one third of patients had been to an emergency department for uncontrolled asthma in the last 5 years, and most of these visits had occurred during the last year. As to knowledge, 406 patients (49%) disagreed with the statement that asthma is a lifelong condition that cannot be cured. Among IC users, only 101 (30%) knew that IC reduced airway inflammation; among beta 2-agonist users, only 33% agreed that beta 2-agonists opened the bronchial tubes. Two hundred forty patients (29%) reported being current cigarette smokers, and 381 (46%) reported having pets at home. CONCLUSIONS: Daily symptoms and daily use of beta 2-agonists are common among Canadian asthma patients, and this is in excess of what is considered acceptable by current asthma care guidelines. Underuse of IC, inadequate knowledge of asthma symptoms and treatments, and failure to avoid asthma triggers were common in the population studied.
PMCID: PMC2328364  PMID: 10424270
14.  Increasing prevalence of asthma diagnosis and symptoms in children is confined to mild symptoms 
Thorax  2001;56(4):312-314.
BACKGROUND—The prevalence of childhood asthma is increasing but few studies have investigated trends in asthma severity. We investigated trends in asthma diagnosis and symptom morbidity between an eight year time period in a paired prevalence study.
METHODS—All children in one single school year aged 8-9 years in the city of Sheffield were given a parent respondent questionnaire in 1991 and 1999 based on questions from the International Survey of Asthma and Allergy in Children (ISAAC). Data were obtained regarding the prevalence of asthma and wheeze and current (12month) prevalences of wheeze attacks, speech limiting wheeze, nocturnal cough and wheeze, and exertional symptoms.
RESULTS—The response rates in 1991 and 1999 were 4580/5321 (85.3%) and 5011/6021 (83.2%), respectively. There were significant increases between the two surveys in the prevalence of asthma ever (19.9% v 29.7%, mean difference 11.9%, 95% confidence interval (CI) 10.16to 13.57, p<0.001), current asthma (10.3% v 13.0%, mean difference 2.7%, 95% CI 1.44 to 4.03, p<0.001), wheeze ever (30.3% v 35.8%, mean difference 5.7%, 95% CI 3.76 to 7.56, p<0.001), wheeze in the previous 12 months (17.0% v 19.4%, mean difference 2.5, 95% CI 0.95 to 4.07, p<0.01), and reporting of medication use (16.9% v 20%, mean difference 3.0%, 95% CI 1.46 to 4.62, p<0.001). There were also significant increases in reported hayfever and eczema diagnoses.
CONCLUSIONS—Diagnostic labelling of asthma and lifetime prevalence of wheeze has increased. The current 12 month point prevalence of wheeze has increased but this is confined to occasional symptoms. The increased medication rate may be responsible for the static prevalence of severe asthma symptoms. The significant proportion of children receiving medication but reporting no asthma symptoms identified from our 1999 survey suggests that some children are being inappropriately treated or overtreated.

PMCID: PMC1746019  PMID: 11254824
15.  Inhalation Incidents and Respiratory Health: Results From the European Community Respiratory Health Survey 
Inhalation incidents are an important cause of acute respiratory symptoms, but little is known about how these incidents affect chronic respiratory health.
We assessed reported inhalation incidents among 3,763 European Community Respiratory Health Survey (ECRHS) participants with and without cough, phlegm, asthma, wheezing or bronchial hyperresponsiveness. We then examined whether inhalation incidents during the 9-year ECRHS follow-up period were associated with a new onset of any of these respiratory outcomes among 2,809 participants who were free of all five outcomes at the time of the baseline ECRHS survey.
Inhalation incidents were reported by 5% of participants, with higher percentages reported among individuals with asthma-related outcomes at the time of the baseline survey. Among participants without symptoms at baseline, our analyses generated non-statistically significant elevated estimates of the risk of cough, phlegm, asthma and wheezing and a non-statistically significant inverse estimate of the risk of bronchial hyperresponsiveness among participants who reported an inhalation incident compared to those without such an event reported.
Our findings provide limited evidence of an association between inhalation incidents and asthma-related symptoms. These data could be affected by differences in the reporting of inhalation incidents according to symptom status at the time of the baseline survey; they should thus be interpreted with caution.
PMCID: PMC2642920  PMID: 18942122
accident; asthma; epidemiology; inhalation; respiratory health
16.  Comparison of prevalence and severity of asthma among adolescents in the Caribbean islands of Trinidad and Tobago: results of a nationwide cross-sectional survey 
BMC Public Health  2005;5:96.
Asthma is a growing problem in the Caribbean but the prevalence in most islands is unknown and possible inter-island variation in prevalence has not been determined. A nationwide cross-sectional survey was conducted to compare the prevalence of asthma symptoms among high school students in the two islands of the Republic of Trinidad and Tobago.
Questionnaire and video instruments based on those developed by the International Study of Asthma & Allergy in Childhood (ISAAC) were used to assess asthma prevalence among 6394 children (age range, 11–19 years; mean age, 14.08 yrs) in the second and third years of 35 randomly selected high schools in Trinidad and Tobago. This cross sectional survey was conducted between September and December 2002.
A total of 4988 questionnaires were available for analysis (3519 in Trinidad and 1469 in Tobago). Among respondents from the two islands, there were no significant differences in the prevalence of ever wheezing (24.1% and 24.3% for Trinidad and Tobago, respectively, RR 0.99, 95% CI, 0.90–1.08); wheezing in the previous 12 months (13.1% & 13.4%, RR 0.98, 95% CI 0.84–1.15); a previous or current diagnosis of asthma (12.8% & 13.5%, RR 0.95, 95% CI 0.82–1.12) and night cough in the past 12 months (35.4% & 38.3%, RR0.93, 95% CI 0.86–1.00). However, symptoms of severe asthma were significantly more common among students from Tobago and included having had more than one acute attack in the past year (13.4% & 15.8%, RR 0.85, 95% CI 0.73–1.00, p = 0.0004), night waking as a result of wheeze (7.4% & 10.9%, RR 0.68, 95% CI 0.56–0.83, p < 0.0001) and speech limitation in the past year (5.2% & 8.7%, RR 0.59, 95% CI 0.47–0.74, p < 0.001) Exercise-associated wheezing was also more frequent among Tobagonian adolescents (17.5% & 20.2%, RR 0.87, 95% CI 0.76 – 0.98, p = 0.04).
Self-reported wheeze is common among adolescents in Trinidad and Tobago. Variation in symptoms was found between the two territories; high school students from Tobago, the less industrialized of the two islands, reported more symptoms of severe asthma and exercise-induced wheeze. Difference in the ethnic composition rather than socio-economic factors may be contributing to the observed differences in symptom prevalence.
PMCID: PMC1249582  PMID: 16162294
17.  Prevalence of asthma, rhinitis and eczema among children in 2 Canadian cities: the International Study of Asthma and Allergies in Childhood 
BACKGROUND: Wide variations in the prevalence of asthma, rhinitis and eczema have been reported between regions within Canada and between different countries. The International Study of Asthma and Allergies in Childhood (ISAAC) was developed to provide a standardized tool and methodology to ascertain the prevalence of asthma and allergies in different regions. Comparisons of prevalence rates across geographic regions and at different times may help to identify factors that contribute to the development of these conditions in individuals. METHODS: Two Canadian centres, Hamilton and Saskatoon, participated in the ISAAC. A standard questionnaire was distributed through schools and completed by 13- and 14-year-old children and by the parents of 6- and 7-year-old children. Prevalence rates and 95% confidence intervals were calculated for asthma, wheezing, rhinitis and eczema. RESULTS: The overall response rates were 75.1% among the children 6 and 7 years old and 68.6% among those 13 and 14 years old. Among the younger children, the lifetime prevalence of asthma was 17.2% in Hamilton and 11.2% in Saskatoon; the corresponding rates among the older children were 19.2% and 12.2% respectively. The prevalence of wheezing in the 12 months before the survey in the younger group was 20.1% in Hamilton and 14.1% in Saskatoon; in the older group it was 30.6% and 24.0% respectively. The prevalence of rhinitis in the 12 months before the survey was 28.6% in Hamilton and 22.6% in Saskatoon in the younger group and 45.8% and 33.8% respectively in the older group. The prevalence of eczema was slightly higher in Saskatoon in both age groups. INTERPRETATION: High prevalence rates of asthma, rhinitis and eczema exist among school children in Hamilton and Saskatoon, similar to rates in other Western countries. Further studies are required to determine the factors associated with the high rates in the 2 regions and possible reasons for the higher rates in Hamilton.
PMCID: PMC1230435  PMID: 10405666
18.  Prevalence of asthma and risk factors for asthma-like symptoms in Aboriginal and non-Aboriginal children in the northern territories of Canada 
Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children.
To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada.
Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months.
After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother’s daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother’s daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children.
Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.
PMCID: PMC2677938  PMID: 18437256
Aboriginals; Asthma; Children; Remote area; Risk factors; Smoking
19.  Association of asthma and hay fever with irregular menstruation 
Thorax  2005;60(6):445-450.
Background: There is some evidence that asthmatic women are more likely to have abnormal sex hormone levels. A study was undertaken to determine whether asthma and allergy were associated with irregular menstruation in a general population, and the potential role of asthma medication for this association.
Methods: A total of 8588 women (response rate 77%) participated in an 8 year follow up postal questionnaire study of participants of the ECRHS stage I in Denmark, Estonia, Iceland, Norway, and Sweden. Only non-pregnant women not taking exogenous sex hormones were included in the analyses (n = 6137).
Results: Irregular menstruation was associated with asthma (OR 1.54 (95% CI 1.11 to 2.13)), asthma symptoms (OR 1.47 (95% CI 1.16 to 1.86)), hay fever (OR 1.29 (95% CI 1.05 to 1.57)), and asthma preceded by hay fever (OR 1.95 (95% CI 1.30 to 2.96)) among women aged 26–42 years. This was also observed in women not taking asthma medication (asthma symptoms: OR 1.44 (95% CI 1.09 to 1.91); hay fever: OR 1.27 (95% CI 1.03 to 1.58); wheeze preceded by hay fever: OR 1.76 (95% CI 1.18 to 2.64)). Irregular menstruation was associated with new onset asthma in younger women (OR 1.58 (95% CI 1.03 to 2.42)) but not in women aged 42–54 years (OR 0.62 (95% CI 0.32 to 1.18)). The results were consistent across centres.
Conclusions: Younger women with asthma and allergy were more likely to have irregular menstruation. This could not be attributed to current use of asthma medication. The association could possibly be explained by common underlying metabolic or developmental factors. The authors hypothesise that insulin resistance may play a role in asthma and allergy.
PMCID: PMC1747439  PMID: 15923242
20.  Diagnostic and treatment behaviour in children with chronic respiratory symptoms: relationship with socioeconomic factors 
Thorax  2002;57(8):701-704.
Background: The prevalence and severity of asthma is believed to increase with increasing socioeconomic deprivation. The relationship between asthma diagnosis, symptoms, diagnostic accuracy, and socioeconomic deprivation as determined by Townsend scores was determined in Sheffield schoolchildren.
Methods: All 6021 schoolchildren aged 8–9 years in one school year in Sheffield were given a parent respondent survey based on International Survey of Asthma and Allergies in Childhood (ISAAC) questions.
Results: 5011/6021 (83.2%) questionnaires were returned. Postcode data were available in 4131 replies (82.4%) and were used to assign a composite deprivation score (Townsend score). Scores were divided into five quintiles, with group 1 being least and group 5 being most deprived. A positive trend was observed from group 1 to group 5 for the prevalence of wheeze in the previous 12 months, wheeze attacks ≥4/year, nocturnal wheeze and cough (all p<0.001), cough and/or wheeze "most times" with exertion (p<0.03), current asthma (p<0.001), and significant asthma symptoms (p<0.001). No significant trend was observed for lifetime wheeze or attacks of speech limiting wheeze. There were no significant trends in the prevalence of current asthmatic children without significant symptoms (overdiagnosis) or children with significant asthma symptoms but no current asthma diagnosis (underdiagnosis) across the social groups. There was a significant negative trend in the ratio of asthma medication to asthma diagnosis from least to most deprived groups (p<0.001).
Conclusions: Asthma morbidity and severity increase according to the level of socioeconomic deprivation. This may be due to differences in environment, asthma management, and/or symptom reporting. Diagnostic accuracy does not vary significantly across deprivation groups but children living in areas of least deprivation and taking asthma medication are less likely to be labelled as having asthma, suggesting diagnostic labelling bias.
PMCID: PMC1746399  PMID: 12149530
21.  Cigarette smoking gives more respiratory symptoms among women than among men The Nord-Trøndelag Health Study (HUNT) 
STUDY OBJECTIVE—Studies have indicated that women are more vulnerable to the effect of tobacco smoking compared with men. The aim of this study was to explore the prevalence of reported respiratory symptoms and diseases according to smoking burden, age and sex.
DESIGN—Questionnaire in a cross sectional population based study.
SETTING—The BONT (Bronchial obstruction in Nord-Trøndelag) study is part of a comprehensive health survey of all inhabitants aged above 19 years in the county of Nord-Trøndelag, Norway, which was carried out from 1995 to 1997.
PARTICIPANTS—A total of 65 717 subjects, 71.3% of the total population aged 20-100, answered the main questionnaire.
MAIN RESULTS—In all, 12.7% men and 12.1% women reported episodes of wheezing or breathlessness during the past 12 months, 8.8% men and 8.4% women reported that they had or had had asthma, 7.5% men and 8.2% women had ever used asthma medication, and 4.0% men and 3.0% women reported chronic bronchitis. Thirty per cent of men and 31% of women were smokers, and average pack years of smoking were 15.9 and 10.3, respectively. Among previous and current smokers, significant more women reported episodes of wheezing or breathlessness, current asthma and persistent coughing compared with men with the same smoke burden (pack years) and daily number of cigarettes.
CONCLUSION—The prevalence of reported asthma and use of asthma medication was higher than reported in previous Scandinavian studies. Respiratory symptoms increased by smoking burden. Comparing the prevalence of symptoms and current asthma among women and men with the same smoke burden or daily cigarette consumption, women seemed to be more susceptible to the effect of tobacco smoking than men.

Keywords: asthma; chronic bronchitis; coughing; tobacco smoking
PMCID: PMC1731608  PMID: 11076988
22.  528 Elevated Asthma Prevalence in Mexican-American Children in El Paso, Texas 
The World Allergy Organization Journal  2012;5(Suppl 2):S184-S185.
In the United States, among Hispanics, Mexican American have the lowest rate of asthma1,2 This study was designed to determine the prevalence of asthma among 5 to 17 year-old children, in El Paso Texas, a community area with a 65.8 % of Hispanic of origin Mexican families.
Of March 2006 to May 2010, a cross-sectional screening survey was administered to 1108 children of 751 families selected at random from 50 strata of the El Paso County. We used self-reported history of physician-diagnosed asthma. Data were analyzed to determine the prevalence of lifetime and current asthma. Associations between asthma outcomes and variable trigger were evaluated. Chi-square tests were used for statistical comparison. A P value less than 0.05 was considered to be significant. Multivariate logistic regression (GENMOD) adjusting for repeated measures for the family was used to determine the risk of childhood asthma.
Self-reported physician-diagnosed asthma was reported for 25.8 % of children, and current asthma identified in 20.5 % respectively. The prevalence was statistically higher in boys than tin girls (P < 0.05). 243 (90%) Children asthmatics are atopic and 437 (51.8%) children non-asthmatics are atopic. Smoking occurred inside 23.8% of households.26.3% of children had an indoor dog or cat and 21.2% of caregivers reported cockroaches inside the home.
Prevalence of physician-diagnosed asthma in Hispanic of Mexican origin, ever asthma and current asthma, were higher than those reported from the Centers for Disease Control and Prevention, the prevalence of asthma in 2007. Although most children with asthma are atopic (90%) a significant proportion (51.8 %) of atopic children do not have asthma. Children with a parent with asthma were almost twice as likely (OR = 2.40) to have asthma compared those without a parent with asthma. Children with a parent and grandparent with asthma were over 4 times likely to have asthma compared to those without a parent and grandparent with asthma (OR = 4.97). Maternal asthma confers greater asthma risk to offspring than do paternal or parental asthma.
PMCID: PMC3512841
23.  Examining asthma quality of care using a population-based approach 
Asthma accounts for considerable burden on health care, but in most cases, asthma can be controlled. Quality-of-care indicators would aid in monitoring asthma management. We describe the quality of asthma care using a set of proposed quality indicators.
We performed a retrospective cross-sectional study using health databases in Saskatchewan, a Canadian province with a population of about 1 million people. We assessed 6 quality-of-care indicators among people with asthma: admission to hospital because of asthma; poor asthma control (high use of short-acting β-agonists, admission to hospital because of asthma or death due to asthma); no inhaled corticosteroid use among patients with poor control; at least moderate inhaled corticosteroid use among patients with poor control; high inhaled corticosteroid use and use of another preventer medication among patients with poor control; and any main preventer use among patients with poor control. We calculated crude and adjusted rates with 95% confidence intervals. We tested for differences using the χ2 test for proportions and generalized linear modelling techniques.
In 2002/03, there were 24 616 people aged 5–54 years with asthma in Saskatchewan, representing a prevalence of 3.8%. Poor symptom control was observed in 18% of patients with asthma. Among those with poor control, 37% were not dispensed any inhaled corticosteroids, and 40% received potentially inadequate doses. Among those with poor control who were dispensed high doses of inhaled corticosteroids, 26% also used another preventer medication. Hospital admissions because of asthma were highest among those aged 6–9 years and females aged 20–44 years. Males and those in adult age groups (predominantly 20–44 years) had worse quality of care for 4 indicators examined.
Suboptimal asthma management would be improved through increased use of inhaled corticosteroids and preventer medications, and reduced reliance on short-acting β-agonist medications as recommended by consensus guidelines.
PMCID: PMC2276554  PMID: 18390944
24.  Wheeze, asthma diagnosis and medication use: a national adult survey in a developing country 
Thorax  2005;60(11):895-901.
Background: As relatively little is known about adult wheeze and asthma in developing countries, this study aimed to determine the predictors of wheeze, asthma diagnosis, and current treatment in a national survey of South African adults.
Methods: A stratified national probability sample of households was drawn and all adults (>14 years) in the selected households were interviewed. Outcomes of interest were recent wheeze, asthma diagnosis, and current use of asthma medication. Predictors of interest were sex, age, household asset index, education, racial group, urban residence, medical insurance, domestic exposure to smoky fuels, occupational exposure, smoking, body mass index, and past tuberculosis.
Results: A total of 5671 men and 8155 women were studied. Although recent wheeze was reported by 14.4% of men and 17.6% of women and asthma diagnosis by 3.7% of men and 3.8% of women, women were less likely than men to be on current treatment (OR 0.6; 95% confidence interval (CI) 0.5 to 0.8). A history of tuberculosis was an independent predictor of both recent wheeze (OR 3.4; 95% CI 2.5 to 4.7) and asthma diagnosis (OR 2.2; 95% CI 1.5 to 3.2), as was occupational exposure (wheeze: OR 1.8; 95% CI 1.5 to 2.0; asthma diagnosis: OR 1.9; 95% CI 1.4 to 2.4). Smoking was associated with wheeze but not asthma diagnosis. Obesity showed an association with wheeze only in younger women. Both wheeze and asthma diagnosis were more prevalent in those with less education but had no association with the asset index. Independently, having medical insurance was associated with a higher prevalence of diagnosis.
Conclusions: Some of the findings may be to due to reporting bias and heterogeneity of the categories wheeze and asthma diagnosis, which may overlap with post tuberculous airways obstruction and chronic obstructive pulmonary disease due to smoking and occupational exposures. The results underline the importance of controlling tuberculosis and occupational exposures as well as smoking in reducing chronic respiratory morbidity. Validation of the asthma questionnaire in this setting and research into the pathophysiology of post tuberculous airways obstruction are also needed.
PMCID: PMC1747242  PMID: 16263947
25.  Clinically diagnosed childhood asthma and follow-up of symptoms in a Swedish case control study 
BMC Family Practice  2005;6:16.
Childhood asthma has risen dramatically not only in the western societies and now forms a major and still increasing public health problem. The aims of this study were to follow up at the age of ten the patterns of asthma symptoms and associations among children with a clinically diagnosed asthma in a sizeable urban-rural community and to in compare them with demographic controls using a standardised questionnaire.
In a defined region in Sweden with a population of about 150 000 inhabitants, all children (n = 2 104) born in 1990 were recorded. At the age of seven all primary care and hospital records of the 1 752 children still living in the community were examined, and a group of children (n = 191) was defined with a well-documented and medically confirmed asthma diagnosis. At the age of ten, 86 % of these cases (n = 158) and controls (n = 171) completed an ISAAC questionnaire concerning asthma history, symptoms and related conditions.
Different types of asthma symptoms were highly and significantly over-represented in the cases. Reported asthma heredity was significantly higher among the cases. No significant difference in reported allergic rhinitis or eczema as a child was found between cases and controls. No significant difference concerning social factors or environmental exposure was found between case and controls. Among the control group 4.7 % of the parents reported that their child actually had asthma. These are likely to be new asthma cases between the age of seven and ten and give an estimated asthma prevalence rate at the age of ten of 15.1 % in the studied cohort.
A combination of medical verified asthma diagnosis through medical records and the use of self-reported symptom through the ISAAC questionnaire seem to be valid and reliable measures to follow-up childhood asthma in the local community. The asthma prevalence at the age of ten in the studied birth cohort is considerably higher than previous reports for Sweden. Both the high prevalence figure and allowing the three-year lag phase for further settling of events in the community point at the complementary roles of both hospital and primary care in the comprehensive coverage and control of childhood asthma in the community.
PMCID: PMC1090570  PMID: 15845146

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