The effectiveness of varenicline versus nicotine replacement therapy on long-term smoking cessation in primary care: a prospective cohort study of electronic medical records.
Background
There is limited evidence about the effectiveness of varenicline and nicotine replacement therapy (NRT) for long-term smoking cessation in primary care, or whether the treatment effectiveness differs by socioeconomic position (SEP). Therefore, we estimated the long-term effectiveness of varenicline versus NRT (> 2 years) on smoking cessation, and investigated whether effectiveness differs by SEP.


Methods
This is a prospective cohort study of electronic medical records from 654 general practices in England, within the Clinical Practice Research Datalink, using three different analytical methods: multivariable logistic regression, propensity score matching and instrumental variable analyses. Exposure was prescription of varenicline versus NRT, and the primary outcome was smoking cessation at 2 years' follow-up; outcome was also assessed at 3, 6, and 9 months, and at 1 and 4 years after exposure. SEP was defined using the Index of Multiple Deprivation.


Results
At 2 years, 28.8% (N = 20 362/70 610) of participants prescribed varenicline and 24.3% (N = 36 268/149 526) of those prescribed NRT quit; adjusted odds ratio was 1.26 [95% confidence interval (CI): 1.23 to 1.29], P < 0.0001. The association persisted for up to 4 years and was consistent across all analyses. We found little evidence that the effectiveness of varenicline differed greatly by SEP. However, patients from areas of higher deprivation were less likely to be prescribed varenicline; adjusted odds ratio was 0.91 (95% CI: 0.90 to 0.92), P < 0.0001.


Conclusions
Patients prescribed varenicline were more likely to be abstinent up to 4 years after first prescription than those prescribed NRT. In combination with other evidence, the results from this study may be used to update clinical guidelines on the use of varenicline for smoking cessation.
['Taylor|Gemma M J|GMJ|', 'Taylor|Amy E|AE|', 'Thomas|Kyla H|KH|', 'Jones|Timothy|T|', 'Martin|Richard M|RM|', 'Munafò|Marcus R|MR|', 'Windmeijer|Frank|F|', 'Davies|Neil M|NM|']
D000328:Adult D057286:Electronic Health Records D004739:England D005260:Female D005500:Follow-Up Studies D006801:Humans D016015:Logistic Models D008297:Male D008875:Middle Aged D015999:Multivariate Analysis D009538:Nicotine D011320:Primary Health Care D057216:Propensity Score D011446:Prospective Studies D016540:Smoking Cessation D012923:Social Class D013997:Time Factors D061485:Tobacco Use Cessation Devices D016896:Treatment Outcome D000068580:Varenicline
effectiveness varenicline nicotine replacement therapy Smoking cessation primary care cohort electronic medical records instrumental variable causal tobacco