[Survey of the effects of smoking in an occupational cohort study. Value and limits of a new method].
BACKGROUND
This paper proposes a method to take smoking into account in occupational cohort studies when a lung cancer excess is observed and no information on smoking is available.


METHODS
The model consists in assessing the proportion of smokers in the study cohort on the basis of (i) the relative risk observed for lung cancer (P1), and (ii) relative risks due to other smoking related diseases (P2). If P1 is higher than P2, it is concluded that the observed lung cancer excess is unlikely to be due to smoking.


RESULTS
The model was applied to nine epidemiological studies, of which five showed a lung cancer excess (ranged between 1.12 et 1.32). The P2 proportions of four of these five studies ranged between 0.29 and 0.46, and were lower than P1 that ranged between 0.57 and 0.69. These differences reached statistical significance. These results suggest that occupational lung cancer risks might have existed. The model was validated by applying to cohorts without lung cancer excess and to cohorts of smokers and non smokers. The robustness was assessed using different values of the basic parameters: proportion of smokers in the general population and risks due to smoking for smoking related diseases.


CONCLUSIONS
This model is an assessment of the relative importance of smoking and occupational factors in occupational cohort studies, in the absence of information on smoking.
Moulin
J J
JJ
Institut National de Recherche et de Sécurité (INRS), Service d'Epidémiologie, Vandoeuvre-lès-Nancy.
Wenger
V
V
Wild
P
P
D001984:Bronchial Neoplasms / Q000737:chemistry* / Q000453:epidemiology; D001991:Bronchitis / Q000139:chemically induced / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D015233:Models, Statistical; D009062:Mouth Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D009784:Occupational Diseases / Q000453:epidemiology*; D016273:Occupational Exposure; D011656:Pulmonary Emphysema / Q000139:chemically induced / Q000453:epidemiology; D015203:Reproducibility of Results; D012907:Smoking / Q000009:adverse effects*