Peak expiratory flow in symptomless elderly smokers and ex-smokers.

Values of peak expiratory flow (PEF) in 142 current smokers (116 men, 26 women) and 108 ex-smokers (88 men, 20 women) aged 55 or over were compared with the predicted values obtained in lifelong nonsmokers of the same age range. None of the subjects had been liable during childhood or subsequently to expectoration, lower respiratory tract infection, wheeze, or shortness of breath. Observed values of PEF were expressed as differences from predicted. Analysis of the relation between smoking state and ventilatory function in the men disclosed significant reductions of PEF in current smokers, the deficits increasing with the amount smoked from a mean of 48.1 l/min in those smoking fewer than 20 cigarettes a day to 73.3 l/min in smokers of 20 or more a day. Significant reductions of PEF were also found in women who were currently smoking (mean 47.4 l/min) and in male ex-smokers of 20 or more cigarettes a day (mean 27.8 l/min). There was no significant reduction of PEF in male or female ex-smokers of fewer than 20 cigarettes a day. These findings suggest that factors besides smoking are concerned in the development of irreversible airflow obstruction.