Changes after quitting cigarette smoking.

Changes in cardiorespiratory symptoms and coronary disease risk indicators over an average 1 1/2-year period were assessed in 9392 persistent cigarette smokers and 3825 persons who quit smoking between two multiphasic checkups. The prevalence of questionnaire-reported chronic cough fell markedly in subjects who quit a one-or-more-pack/day habit (e.g., from 11.2% to 1.8% in white men, p less than 0.001). However, chest pain, shortness of breath and exertional leg pain showed no consistent improvement in quitters compared with persistent smokers. Weight gain was about 2-3 lbs greater in quitters, but changes in blood pressure were small and not consistent across race-sex groups, nor were there consistent differences between persistent smokers and quitters in trends in trends in vital capacity, cholesterol or prevalence of ECG abnormality. Quitting was associated with increase in serum uric acid levels of about 0.2-0.5 mg/dl and relative falls in hemoglobin, leukocyte count and serum glucose levels, all consistent with smoker-nonsmoker differences previously found in cross-sectional studies. Except for the small increases in weight and uric acid levels, quitting smoking did not appear to increase risk of coronary heart disease by other mechanisms.