[Effect of smoking on the decline in forced expiratory volume in one second]

We used multiple regression analysis to study the effects of smoking cessation on the decline in forced expiratory volume in one second (FEV1). We studied 429 healthy men for about 3 years. Each subject was assigned to one of three groups, according to their self-reported smoking history: 281 were current smokers, 67 were former smokers, and 81 had never smoked. After statistical adjustment for initial age, initial FEV1, and decline in Maximum Mid-expiratory Flow (MMF), current smoking was found to be associated with a faster decline in FEV1. Having stopped smoking was associated with a slower decline in FEV1. The rate of decline in MMF was associated with the rate of decline in FEV1, which suggests that the rate of decline in FEV1 was greater in those subjects with small airways disease.