Decline in lung function and mortality: The Busselton Health Study

Background-There is a direct association between level of lung function, me asured by forced expiratory volume in 1 second (FEV1) and mortality rates. A low FEV1 may result from an increased decline in FEV1 with age, which may be an independent predictor of mortality. Objective-To examine the association between decline in FEV1 and mortality in a cohort from a community health study. Setting and methods-From five cross sectional studies in Busselton between 1969 and 1981 a cohort of 751 men and 940 women was identified who had thre e assessments of lung function over a six year period and had other health related data collected. Each subject's average FEV1 and decline in FEV1 (li tre/year) were calculated from these three measurements. Mortality follow u p to December 1995 was obtained. Cause of death was taken as the certified cause of death from the death certificate using ICD9 categories. Results-The average decline in FEV1 was 0.04 litre per year (SD = 0.07) for men and 0.03 litre per year (SD = 0.06) for women. Average FEV1 was signif icantly associated with all cause and cardiovascular disease mortality in b oth sexes. In women there was a significant association between decline in FEV1 and death from all causes, after adjusting for average FEV1, age, smok ing, coronary heart disease, and cardiovascular disease risk factors; a 0.0 5 Litre per year increase in the rate of decline of FEV1 increased the risk of death for all causes by 1.23 (95% confidence interval 1.06, 1.44). In m en the effect of decline in FEV1 on death rate was less; for all men the ha zard ratio for a 0.05 litre/year greater decline in FEV1 was 1.19 (0.99, 1. 21). Conclusion-Decline in lung function, measured by FEV1 is a predictor of dea th, independent of average FEV1 and risk factors for cardiovascular disease .