Evolution of disability in coalworkers' pneumoconiosis.

Retrospective analysis of the results of serial ventilatory capacity tests (FEV 1-0), which had extended over an average period of almost 15 years, has been carried out in 215 miners and ex-miners who suffer with coalworkers' pneumoconiosis. All were unselected previously diagnosed cases who attend the Cardiff Pneumoconiosis Panel at regular intervals for re-assessment examinations. They consisted of 68 miners and 147 ex-miners and they were divided into three groups according to their radiological category at their most recent examination, carried out in either 1973 or 1974. There were 90 cases of category B progressive massive fibrosis (PMF), 50 cases of category A PMF and 75 cases of simple pneumoconiosis. Findings for the 38 life-long non-smokers within the 215 were compared with those for the smokers. All three groups showed progressive impairment of ventilation over the whole period of observation. This was most marked in the category B cases but this group had already acquired a substantial proportion of their eventual impairment while still classified radiologically as category A or as simple pneumoconiosis. These findings are not compatible with the view that coalworkers' pneumoconiosis does not cause significant impairment of ventilation until the category B radiological stage is attained; they suggest rather that cases destined to progress to serious disablement show evidence of progressive impairment of ventilation at very much earlier radiological stages. Non-smokers showed a pattern of impairment similar to that of the smokers but were less disabled; the differences, however, were slight and not statistically significant.