Long-term mortality among adults with or without asthma in the PAARC study

Abstract

The Pollution Atmosphérique et Affections Respiratoires Chroniques (PAARC; Air Pollution and Chronic Respiratory Diseases) study provided the opportunity to examine the 25-yr mortality of 940 asthmatic adults drawn from a large population-based sample of 14,267 adults investigated during 1974-1976 in seven French cities. Vital statistics were collected in 2001 for the whole population. Multivariate survival analysis was used to assess exact survival rates in asthmatics and nonasthmatics taking relevant confounders into account. On average, the mortality rates obtained were 10.4 and 6.9 deaths 1,000 person-yrs-1 asthmatics and nonasthmatics, respectively. On univariate analysis, asthma increased the relative risk (RR) of death by 1.48 (95% confidence interval (CI) 1.29-1.69). The association between asthma and death had an RR of 1.16 (95% CI 0.99-1.37) when age, sex, educational level, smoking habits, occupational exposure and forced expiratory volume in one second (FEV1) were taken into account. FEV1 was an important contributive factor causing increased risk of death in both smokers and nonsmokers. For instance, in asthmatics, the numbers of deaths due to respiratory disease and cancer appeared excessive. The present study suggests that asthmatics exhibit a higher risk of mortality.