Prevalence of obstructive lung disease in a general population: relation to occupational title and exposure to some airborne agents

Our plain-English summary of Prevalence of obstructive lung disease in a general population: relation to occupational title and exposure to some airborne agents, by P.S. Bakke, V. Baste, R. Hanoa, et al (Thorax, 1991).

The study

• Authors: P.S. Bakke, V. Baste, R. Hanoa, A. Gulsvik
• Journal: Thorax
• Published: 1991;46(12):863-70
• Cited by: 189 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: The importance of occupational exposure to airborne agents in the development of obstructive disease is uncertain. Studying the relation in a community population has the benefit of reducing the healthy worker effect seen in studies of working populations.

Methods: The prevalence of obstructive lung disease was examined in a Norwegian general population aged 18-73 in a two phased cross sectional survey. In the second phase a stratified sample (n = 1512) of those responding in the first phase was invited for clinical and spirometric examination (attendance rate 84%). Attenders were asked to state all jobs lasting greater than 6 months since leaving school and to say whether they had been exposed to any of seven specific agents and work processes potentially harmful to the lungs.

Results: The prevalence of asthma and chronic obstructive lung disease was 2.4% and 5.4%, respectively; spirometric airflow limitation (FEV1/FVC less than 0.7 and FEV1 less than 80% of predicted values) was observed in 4.5% of the population. All jobs were categorised into three groups according to the degree of potential airborne exposure. Having a job with a high degree of airborne exposure increased the sex, age, and smoking adjusted odds ratio for obstructive lung disease (asthma and chronic obstructive lung disease) by 3.6 (95% confidence interval 1.3 to 9.9) compared with having a job without airborne exposure; the association with spirometric airflow limitation was 1.4 (0.3 to 5.2). Occupational exposures to quartz, metal gases, aluminium production and processing, and welding were significantly associated with obstructive lung disease after adjusting for sex, age, and smoking habit, the adjusted odds ratios varying between 2.3 and 2.7. Occupational exposure to quartz and asbestos was significantly related to spirometric airflow limitation in people older than 50.

Conclusion: Occupational title and exposure to specific agents and work processes may be independent markers of obstructive lung disease in the general population.

In plain English

This was a two-phase cross-sectional survey in Bergen and 11 surrounding municipalities, Norway. Of 1512 people invited to a clinical and breathing-test examination in 1987-8, 1275 (84%) attended, aged 18 to 73. They listed their jobs and said yes or no to past or present work exposure to seven agents and work processes, including asbestos and quartz. Estimated prevalences were 2.4% for asthma, 5.4% for chronic obstructive lung disease and 4.5% for spirometric airflow limitation. In an analysis sample of 714, adjusted for sex, age and smoking, a present job with high anticipated airborne exposure had an odds ratio of 3.6 (95% CI 1.3 to 9.9) for obstructive lung disease, compared with jobs without airborne exposure. Reported asbestos exposure had an odds ratio of 1.7 (0.7 to 3.9) for obstructive lung disease, which was not statistically significant. Among people older than 50, it had an odds ratio of 2.8 (1.1 to 7.3) for airflow limitation. The authors concluded that the study indicates occupational airborne exposure, in addition to smoking, is a risk factor. They urged caution because of small numbers and exposure reports of unknown validity.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Two-phase cross-sectional community survey (postal questionnaire, then clinical and spirometric examination of a stratified sample)
• Who was studied: General population of Bergen and 11 surrounding municipalities, Hordaland county, Norway. From 3370 postal questionnaire respondents, 1512 people were invited (April 1987 to August 1988) and 1275 attended (84%), aged 18-73. Exposure-disease analyses used a re-weighted sample of 714 subjects.
• Exposure: Self-reported (yes/no) past or present occupational exposure to asbestos, quartz, wood dust, metal gases (chromium, nickel, platinum), aluminium production and processing, welding, and soldering. Also occupational title of present job and longest-held job, classed by three experts as no (AE-), moderate (AE+) or high (AE++) anticipated airborne exposure.
• Main results:
  • Estimated prevalence in the general population aged 18-73: asthma 2.4%, chronic obstructive lung disease 5.4%
  • Spirometric airflow limitation (FEV1/FVC less than 0.7 and FEV1 less than 80% of predicted) was observed in an estimated 4.5% of the population
  • A present job with high anticipated airborne exposure (AE++), compared with a job without airborne exposure, had a sex-, age- and smoking-adjusted odds ratio of 3.6 (95% CI 1.3 to 9.9) for obstructive lung disease (asthma or chronic obstructive lung disease). The corresponding odds ratio for spirometric airflow limitation was 1.4 (0.3 to 5.2).
  • Self-reported asbestos exposure was reported by 20 of 85 people with obstructive lung disease and 107 of 629 without. The adjusted odds ratio was 1.7 (0.7 to 3.9) for obstructive lung disease and also 1.7 (0.7 to 3.9) for spirometric airflow limitation; neither was statistically significant.
  • Obstructive lung disease was significantly associated with quartz dust, metal gases, aluminium production and processing, and welding, after adjustment for sex, age and smoking
  • Among people older than 50, the adjusted odds ratio for spirometric airflow limitation was 2.8 (1.1 to 7.3) in those reporting asbestos exposure compared with those not exposed
  • Among people older than 50, the adjusted odds ratio for spirometric airflow limitation was 3.7 (1.2 to 11.0) for quartz exposure
  • Of the agents and work processes, only lifetime prevalence of exposure to asbestos increased with increasing age
• The authors' conclusion: The authors concluded that obstructive lung disease affects more than one in 15 adults in this community. They concluded that the study indicates occupational airborne exposure, in addition to smoking, is an environmental risk factor for the disease.
• Limitations the authors state:
  • The authors stated that findings on specific agents should be interpreted cautiously because of small numbers in each group, high interdependence between agents, and unknown validity of the self-reported exposure information
  • The agents and work processes may be only crude estimates of an unhealthy work environment
  • Small numbers of subjects with spirometric airflow limitation call for cautious interpretation
  • Occupational titles are only crude indicators of working conditions
  • Results may be affected by recall bias
  • Diseased subjects may over-report exposure compared with healthy subjects, which would bias results towards an association

Topics

Medical terms in this study, explained in our Lexicon: Obstructive Lung Disease, Occupational Exposure, Healthy Worker Effect, FEV1/FVC Ratio, FEV1, Odds Ratio, confidence interval, Habit.

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