Respiratory decline in smokers and ex-smokers - an independent risk factorfor cardiovascular disease and death

Background and objective Although smoking is associated with an increased i ncidence of cardiovascular disease and death, many smokers remain healthy a fter many years of smoking. Our objective was to assess whether this variat ion is related to rate of decline of respiratory function. Design This was a population-based cohort study, its subjects being men bor n in 1914 from Malmo, Sweden. Methods All 291 smokers who since the baseline examination in 1969 had rema ined in Malmo were invited to a follow-up examination in 1982. Of the 242 p articipants, 199 men without history of myocardial infarction or stroke wer e included in the study. Eighty-four of them had quit smoking. The incidenc e of cardiovascular disease and death during 14 years was studied in relati on to the decline in lung function [forced expiratory volume during 1 secon d (FEV1.0) and vital capacity] between 55 and 68 years of age. Results Fifty-nine (51%) smokers and 43 (51%) ex-smokers died. Forty-four ( 38%) smokers and 29 (35%) ex-smokers suffered a cardiovascular event. The m ortality rate among smokers in the high, middle and low thirds with regard to the decline in FEV1.0 was 66.5, 44.0, and 37.6, respectively, per 1000 p erson-years (P for trend = 0.04). The corresponding figures in ex-smokers w ere 88.7, 42.0, and 35.1 (P for trend = 0.002). The cardiovascular event ra te among smokers in these three groups was 56.0, 41.0, and 22.7 events, res pectively, per 1000 person-years (P for trend = 0.01). The association rema ined significant after adjustments for potential confounders, A change in v ital capacity was associated with a similar pattern of disease and death. Conclusion Although smoking is associated with an accelerated respiratory d ecline, there are marked differences between smokers. The increased cardiov ascular event and death rates among those whose lung function declined the most suggests that the change in respiratory function can be used as a meas ure of individual susceptibility. (C) 2000 Lippincott Williams & Wilkins.