Reanalysis of a longitudinal study of pulmonary function in coal miners in Lorraine, France

Multiple methods of statistical analysis were applied on data collected on 384 coal miners from the Lorraine region of France. Despite the irregularity of timing of visits over the follow-up period, similar estimates of decline resulted irrespective of the statistical method used. Deceased smokers showed the highest rates of decline in forced expiratory volume during 1 second (FEV1) of 65 to 72 ml/yr, whereas the alive non-smokers had the lowest decline estimates of 42 to 48 ml/yr. Estimates of FVC decline were found to parallel those of FEV1. For about one-half of the cohort, data were available to compare FEV1 decline before and after retirement using a profile analysis. Based upon a "differencing" method of regression, retirement from the coal mine had the effect of decreasing the rate of decline for those who had never smoked; smokers, however, showed an increasing rate of decline.