Quitting and restarting smoking: cohort study of patients with angina in primary care

Participants, methods, and results

Patients clinically diagnosed as having angina at least six months previously were identified from the disease registers of 18 general practices in the Greater Belfast area. These general practices were chosen to represent the diversity of socioeconomic classes and cultures in the area. All patients who agreed to participate in a randomised controlled trial of health education were interviewed at baseline, at two years, and at five years. Those who did not complete the review at two years were not contacted at five years.

Participants were questioned about their smoking habits. Smokers were defined as those who smoked at least one cigarette daily. Full details of the method are reported elsewhere. 3 4

A cohort of 487 patients completed the five year follow up. Of these, 58% (284/487) were male and 44% (213) belonged to socioeconomic groups IV and V (11% (56) were in groups I and II, and 45% (219) were in group III). The mean participant age was 63 (range 38-74; SD 7) years.

Before recruitment 12% (58) of participants had been diagnosed as having angina for six months to one year, 36% (174) two to five years, 23% (115) six to ten years and 29% (140) up to 33 years. Over three quarters of participants (374, 77% (95% confidence interval 73% to 81%)) continued as non-smokers and 58 (12%, 9% to 15%) persisted in smoking (table). Of the 395 participants who were baseline non-smokers, 21 (5%, 3% to 7%) subsequently reported smoking. Of the 92 self reported smokers at baseline, 34 (37%, 27% to 47%) subsequently reported non-smoking.

Fifty five participants (11%, 8% to 14%) changed their smoking habits over the five year period. At baseline, ever having smoked was reported by 346 (71%, 67% to 75%) participants. Of the 21 baseline non-smokers who changed their smoking habits over the five year period, 18 had, previous to this study, smoked cigarettes and two had smoked cigars or a pipe.

Among those who at baseline reported having stopped smoking cigarettes for less than one year, 1 to 5 years, and more than 5 years, 5/16 (31%, 7% to 55%), 4/33 (12%, 1% to 23%), and 9/184 (5%, 3% to 7%) subsequently resumed smoking, respectively.

Comment

Participants in this cohort of patients with angina restarted smoking more than five years after having quit. Such longitudinal changes in self reported smoking status indicate that patients may resume smoking after lengthy periods of abstinence. Periodic inquiry regarding smoking habit is, therefore, worthwhile.

Since more than a third of self reported smokers subsequently reported quitting there is value in promoting smoking cessation among patients with established cardiovascular disease. Similar cycles of abstinence and relapse have been reported in other study populations5; this emphasises the importance of long term follow up in evaluating interventions.