Occupational asthma in the community: risk factors in a western Mediterranean population

Large scale questionnaire survey on respiratory health in Sweden: effects of late- and non-response

BACKGROUND

Participation rates in epidemiologic studies conducted with postal questionnaires have steadily declined since 1970s. This can lead to an increased risk for selection bias. The aim of this study was to examine cause and effect of non-response in a large cross sectional study assessing respiratory health in western Sweden.

METHODS

The study sample was 29,218. The response rate to the initial postal questionnaire was 33%. The response rates to subsequent postal reminders were 15%, 7% and 7% of eligible participants totalling a participation of 62%. Of those who did not respond to the postal survey, a random sample of 400 subjects were identified and contacted for interview by telephone.

RESULTS

Non-responders did not differ significantly in prevalence of airway diseases or symptoms when compared with responders. Male sex, young age and smokers were underestimated among non-responders. No clear trends in prevalence of respiratory symptoms and report of asthma were found with delayed response to the postal survey. The proportion of smokers and men increased with increasing number of reminders. Letters reminding subjects about the study did increase the participation rate but did not alter the risk estimates.

CONCLUSION

We conclude that with a response rate of 62%, our estimate of disease and symptom prevalence was not biased in this Swedish population. However, smoking was underestimated. No general trend for late-responders was seen and therefore we conclude that extrapolation of results to non-responders is not possible in our study. Causes of non-response were mainly due to circumstantial factors.

[Selective loss of participants as a consequence of under-coverage and non-response in research among the aged: an overview]

This article presents an overview of biases in studies among the aged as a consequence of under-coverage and non-response. The question studied is whether participants and non-participants in research differed in their socioeconomic status (education; income; SES of neighbourhood), social integration (marital status; living arrangements; social participation; ethnicity) and health (general health situation; mortality in the period after study; lifestyle and risk factors, namely obesity and alcohol abuse; contact with physicians). In all, 65 studies were reviewed. The results showed that research participants had a higher socioeconomic status, were more integrated socially and in better health than research non-participants. The differences (effect sizes) were small to moderate. On the basis of these results, we can conclude that univariate distributions and prevalence estimates as well as relationships between variables in published research will frequently be biased.

Asthma caused by occupational exposures is common - a systematic analysis of estimates of the population-attributable fraction

Background

The aim of this paper is to highlight emerging data on occupational attributable risk in asthma. Despite well documented outbreaks of disease and the recognition of numerous specific causal agents, occupational exposures previously had been relegated a fairly minor role relative to other causes of adult onset asthma. In recent years there has been a growing recognition of the potential importance of asthma induced by work-related exposures

Methods

We searched Pub Med from June 1999 through December 2007. We identified six longitudinal general population-based studies; three case-control studies and eight cross-sectional analyses from seven general population-based samples. For an integrated analysis we added ten estimates prior to 1999 included in a previous review.

Results

The longitudinal studies indicate that 16.3% of all adult-onset asthma is caused by occupational exposures. In an overall synthesis of all included studies the overall median PAR value was 17.6%.

Conclusion

Clinicians should consider the occupational history when evaluating patients in working age who have asthma. At a societal level, these findings underscore the need for further preventive action to reduce the occupational exposures to asthma-causing agents.

Occupation and adult-onset asthma among Chinese women in a population-based cohort

BACKGROUND

Exposure to industrial irritants is believed to have contributed to the increasing prevalence of asthma worldwide. We examined the associations between occupation and asthma among women in a case-control study nested in the population-based Shanghai Women's Health Study cohort in China.

METHODS

Cases were 1,050 women who reported a physician-diagnosed asthma as adults. Controls were 4,200 women matched to the cases by year of birth and age at diagnosis. Lifetime occupational histories were obtained. Logistic regression was applied to estimate odds ratios (ORs) adjusting for smoking, education, family income, and concurrent chronic bronchitis.

RESULTS

Asthma is more prevalent in production industries for metal tools (OR = 2.4; 1.3-4.7), metal products for everyday use (OR = 1.6; 1.1-2.4), ships (OR = 2.6; 1.0-6.8), and clocks (OR = 1.9; 1.0-3.4), and in occupations as farm workers (OR = 4.0; 1.2-13.0), laboratory technicians and analyzers (OR = 2.2; 1.2-3.9), and installation and maintenance workers for weaving and knitting machineries (OR = 2.4; 1.1-5.4). Other associations less commonly reported were identified for electricians (OR = 2.1; 1.1-4.1), performers (OR = 3.2; 1.4-7.4), administrative workers in organizations and enterprises (OR = 1.8; 1.1-2.8), and postal and telecommunication workers (OR = 3.5; 1.6-7.6).

CONCLUSIONS

Our findings suggest that occupational exposures contribute to the development of asthma in women.

Case-by-case assessment of adult-onset asthma attributable to occupational exposures among members of a health maintenance organization

OBJECTIVE

In a general population of employed persons with health insurance, what proportion of adult-onset asthma is caused by occupational exposures?

METHOD

We conducted a 2-year prospective study to identify adult-onset asthma among health maintenance organization (HMO) members. Telephone interviews regarding occupational exposures, symptoms, medication use, and triggers were used to assess likelihood of work-related asthma for each case. Weighted estimating equations were used to adjust the proportion of asthma attributable to workplace exposures for factors associated with interview participation.

RESULTS

Overall, 29% (95% confidence interval, 25-34%) of adult-onset asthma was attributable to workplace exposures; 26% (21-30%) and 22% (18-27%) of cases had asthma attributable to occupational irritant and sensitizer exposures, respectively.

CONCLUSIONS

Occupational exposures, including irritants, are important causes of adult-onset asthma.

How much adult asthma can be attributed to occupational factors?

PURPOSE

Many occupational factors can cause asthma or reactivate preexisting disease. We carried out a critical review and synthesis of the available literature to estimate the proportion of adult asthma that is attributable to workplace factors.

METHODS

We reviewed published citations from 1966 through May 1999 as well as recent abstracts of studies providing risk estimates for asthma among various occupations. We extracted published attributable risk estimates, derived others from published data, and extrapolated estimates from the incidence rates of occupational asthma. We used a semiquantitative score to rank studies based on their characteristics.

RESULTS

We obtained 43 attributable risk estimates from 19 different countries: 23 were published estimates, 8 were derived from published data, and 12 were extrapolated from incidence data. The median value for the attributable risk of occupationally associated asthma was 9%(25th to 75th interquartile range: 5% to 19%). The derived estimates (median attributable risk = 25%) were significantly greater than published values (median = 9%, P = 0.002), whereas the extrapolated estimates were significantly lower (median = 5%, P = 0.04). The 12 highest scored studies based on their characteristics yielded a median risk estimate of 15%.

CONCLUSION

Occupational factors are associated with about 1 in 10 cases of adult asthma, including new onset disease and reactivation of preexisting asthma.