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Occupational exposures and chronic obstructive pulmonary disease: a hospital based case–control study
  1. Nadira Govender1,
  2. Umesh G Lalloo2,
  3. Rajen N Naidoo1
  1. 1Department of Occupational and Environmental Health, University of KwaZulu-Natal, Durban, South Africa
  2. 2Department of Pulmonology and Critical Care Medicine, University of KwaZulu-Natal, Durban, South Africa
  1. Correspondence to Professor Rajen Naidoo, Department of Occupational and Environmental Health, George Campbell Building, University of KwaZulu-Natal, Durban 4041, South Africa; naidoon{at}


Background Occupational exposures are associated with chronic obstructive pulmonary disease (COPD). This study investigated this association among a population with a high prevalence of tuberculosis and smoking.

Methods Cases (n=110) diagnosed by pulmonologists were selected from specialist respiratory clinics. Frequency sex- and age-matched controls (n=102) were selected from other clinics at the same institutions. Lifetime occupational exposure histories were obtained through interviews. Exposure variables derived from the ALOHA Job Exposure Matrix (JEM) were used to complement the self-reporting variables. ORs were calculated from logistic regression models, adjusting for smoking and past history of tuberculosis. Percentage population attributable risk (PAR%) was also calculated.

Results The adjusted ORs for COPD from the JEM-derived high cumulative biological dust exposure, high cumulative mineral dust exposure and high cumulative gas and fumes exposure were 2.1 (95% CI 1.1 to 4.2), 1.1 (95% CI 0.6 to 2.4) and 1.8 (95% CI 0.8 to 3.9), respectively. Self-reported occupational exposures were associated with higher risks, with adjusted ORs for high dust exposure-years and high chemical, gas and fumes exposure-years of 5.9 (95% CI 2.6 to 13.2) and 3.6 (95% CI 1.6 to 7.9), respectively. Among ever smokers, there was an increased risk for COPD, with ORs ranging from 5.0 to 5.5. Tuberculosis was a strong risk factor, with an OR ranging from 7.7 to 8.1. The PAR% was 25% for self-reported high exposures, but lower when the JEM variables were used.

Conclusions Lifetime occupational exposures contribute to the risk of COPD, adjusted for smoking. These risks are present in populations with a high burden of tuberculosis, which is considered an important causative factor.

  • COPD
  • occupational exposures
  • tuberculosis
  • South Africa
  • COPD epidemiology
  • occupational lung disease

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  • Funding The study was supported through research funds of the University of KwaZulu-Natal.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the University of KwaZulu-Natal Biomedical Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.