Rising mortality from cryptogenic fibrosing alveolitis.

OBJECTIVE: To determine the pattern of mortality ascribed to cryptogenic fibrosing alveolitis and to identify factors that might be important in the aetiology of the disease; and to assess the validity of death certification of the disease. DESIGN: A retrospective examination of mortality ascribed to cryptogenic fibrosing alveolitis in England and Wales between 1979 and 1988 with analysis, by multiple logistic regression, of independent effects of age, sex, region of residence, and social class as indicated by occupation on data for 1979-87; also a retrospective review of hospital records of patients certified as having died of cryptogenic fibrosing alveolitis in Nottingham and of the certified cause of death of patients known to have had the disease. MAIN OUTCOME MEASURES: Time trends in mortality nationally; effects on mortality of age, sex, and region of residence; validity of death certification in Nottingham. RESULTS: The annual number of deaths ascribed to cryptogenic fibrosing alveolitis doubled from 336 in 1979 to 702 in 1988, the increase occurring mainly at ages over 65. Mortality standardised for age for both sexes likewise increased steadily over the period. Deaths due to cryptogenic fibrosing alveolitis were commoner in men (odds ratio 2.24, 95% confidence interval 2.11 to 2.33) and increased substantially with age, being 7.84 (7.24 to 8.49) times higher in subjects aged much greater than 75 than those aged 45-64. Odds ratios of death due to cryptogenic fibrosing alveolitis adjusted for age and sex were increased in the traditionally industrialised central areas of England and Wales (p less than 0.02, maximum odds ratio between regions 1.25), but no significant increase in odds of death was found for manual occupations. Of 23 people whose deaths were registered in Nottingham as having been due to cryptogenic fibrosing alveolitis, 19 were ascertained from clinical records to have had the disease. Only 17 of 45 patients known to have had cryptogenic fibrosing alveolitis in life were recorded as having died from the disease. CONCLUSIONS: The diagnostic accuracy of death certification of cryptogenic fibrosing alveolitis is high, but the number of deaths recorded as being due to the disease may underestimate the number of patients dying with the disease by up to half. Mortality due to the disease is increasing, and the male predominance and regional differences in mortality suggest that environmental factors are important in its aetiology.