Cardiovascular risks in smokers treated with nicotine replacement therapy: a historical cohort study

BACKGROUND: Previous research suggests exposure to nicotine replacement therapy (NRT) may be associated with an increased risk of cardiovascular disease (CVD). METHODS: Using data from the United Kingdom’s Clinical Practice Research Datalink, this study aimed to evaluate CVD events and survival among individuals who attempted smoking cessation with the support of NRT compared with those aided by smoking cessation advice only. We studied CVD outcomes over 4 and 52 weeks in 50,214 smokers attempting to quit – 33,476 supported by smoking cessation advice and 16,738 with the support of NRT prescribed by their primary care physician. Patients were matched (2 smoking cessation advice patients:1 NRT patient) on demographic and clinical characteristics during a baseline year preceding their quit attempt. Cox proportional hazard regression, conditional negative binomial regression model, and conditional logistic regression were used to analyze data. RESULTS: Mean (standard deviation) population age was 47 (11.2) years; 51% were females. Time to first diagnosis of ischemic heart disease (IHD) among NRT and smoking cessation advice patients was similar within the first 4 weeks, but shorter for NRT patients over 52 weeks (hazard ratio [HR]: 1.35, 95% confidence interval [CI]: 1.03–1.77). A similar trend was observed for cerebrovascular disease (HR: 1.54, 95% CI: 1.08–2.19). NRT patients with a prior diagnosis of IHD or cerebrovascular disease had a higher rate of primary or secondary care consultations for IHD or cerebrovascular disease by 52 weeks (rate ratio: 1.50, 95% CI: 1.14–1.99). Patients prescribed NRT had a shorter survival time over 52 weeks, compared with those receiving advice only (HR: 1.39, 95% CI: 1.09–1.76). CONCLUSION: Our findings suggest that treatment with NRT over 4 weeks does not appear to have an impact on cardiovascular risks. However, a longer follow-up period of 52 weeks resulted in an increase in cardiovascular events for patients prescribed NRT, compared with those receiving smoking cessation advice only.