Occupational exposures and risk of chronic obstructive pulmonary disease (COPD) Kjell Torén Section of Occupational and environmental medicine University of Gothenburg and Sahlgrenska University Hospital Gothenburg SWEDEN

Kjuus et al, 1981 Hospital-based case-control study 36 cases with emphysema 72 controls matched for smoking and age Air pollution at workplace>10 år Relative risk 4.1 (1.4-11.8)

Welding

Miners

Other early studies Fletcher C. AMA Arch Ind Health 1958;18:368-373. ”Men who work in dusty trades, especially coal miners, have a higher prevalence of symptoms of bronchitis and emphysema….”

Oxman AD et al. Occupational dust exposure and chronic obstructive pulmonary disease. A systematic overview of the evidence. Am Rev Respir Dis 1993;148:38-48

Oxman, AD et al, 1993 Smoking miners who had worked more then 30 yrs in a dusty work-place showed a three-fold increased risk to developd emphysema compared to those smoking miners not working in a dusty environment.

Oxman, AD et al, 1993 Few cohorts Heavily exposed But – changed our thinking about occupation and COPD

To elucidate whether different definitions of COPD affect the risk estimates To investigate the relation between occupational exposures and CT-confirmed emphysema

General population based study Gothenburg, Sweden 1,050 subjects aged 50 to 64 years Spirometry before and after bronchodilation Local reference values for LLN Extensive questionnaires Logistic regression modeling

Definitions Airway obstruction; FEV1/VC<0.7 (before bronchodilation) COPD (GOLD); FEV1/VC<0.7 (after bronchodilation) COPD (LLN); FEV1/VC<below LLN (after bronchodilation) Physician-diagnosed COPD; Have you ever had COPD diagnosed by a physician?

The extent of emphysema was visually estimated on a four point scale (absent, mild, moderate or severe) in the three zones of each lung. All subjects with mild emphysema in any zone were categorized as having emphysema. Chronic bronchitis; Have you had longstanding cough with phlegm? and If so, did any period last at least three months? and If so have you had such periods at least two years in a row?

Occupational exposure based on three items; “Have you ever been exposed at your workplace for vapor, gas, dust or fumes?”; “Have you in your work been exposed to diesel exhaust?” and “Have you in your work been exposed to welding fumes or metal fumes?” Two exposure groups were defined; 1. VGDF; Exposure to vapor, gases, dusts or fumes. 2. Welding/diesel; Exposure to either VGDF or welding/metal fumes or diesel exhaust

Current VGDF Welding/ smoking diesel Airway obstruction 2.1 1.7 1.8 (n=212) COPD (GOLD) 3.1 1.2 1.3 (n=173) COPD(LLN) 3.0 1.2 1.4 (n=164) Emphysema 15.3 1.6 2.2 (n=98)

Current VGDF Welding/ smoking diesel Physician-diagnosed COPD 2.7 3.3 4.5 (n=25) Chronic bronchitis 1.3 2.3 3.3 (n=76)

Conclusions; No difference in riskestimates between the GOLD or LLN approach Higher risks when using prebronchodilatory values High risk when using physician-diagnosed COPD. Bias? Matter of specificity? CT-defined emphysema was associated with increased risk due to occupational exposures