Key points are not available for this paper at this time.
Summary: A prospective survey of the progression of ventilatory impairment in 56 subjects with mild chronic bronchitis has been carried out over four and a half years. The forced expiratory volume in one second (FEV 1 ) declined by the mean annual rate of 0.05 ± 0.06L. This re‐presents a highly significant annual deterioration of ventilatory function (P < 0.0005). The rate of decline was not related to the initial level of the FEV 1 or to the number of exacerbations of bronchitis, but it was related to the age of the subject. As is usual amongst chronic bronchitic patients there was evidence of a mild degree of reversible airway obstruction as measured by response of the FEV 1 to isoprenaline. The degree of reversible airway obstruction at the beginning of the study was found to be related to the subsequent rate of decline of the FEV 1 (r = 0.50, P < 0.001). Taking this relationship into account, the decline in the FEV 1 was more marked in smokers than in non and ex‐smokers. Among the smokers the serious rates of decline of the FEV 1 tended to occur in those with increased degrees of reversible airway obstruction. It is postulated that in chronic bronchitis even a minor degree of reversible airway obstruction may reflect an under‐lying asthmatic tendency. If so some pathogenic mechanism related to asthma may influence the rate of decline of the FEV 1 in chronic bronchitis.
Barter et al. (Thu,) studied this question.