Pharmacist-Assisted Varenicline Tobacco Cessation Treatment for Veterans
Background: Pharmacists are uniquely positioned to provide tobacco cessation interventions given their medication expertise and accessibility to the public. The purpose of this study was to evaluate the efficacy and safety of management of varenicline by clinical pharmacy specialists (CPSs) compared with other clinicians.
Methods: This retrospective chart review included patients with a varenicline prescription between July 1, 2019, and July 31, 2020. Primary outcomes were reduction in tobacco use at 12 weeks from baseline, continuous abstinence at 12 weeks, adherence to varenicline therapy, and time to first follow-up. For safety evaluation, charts were reviewed for documented adverse drug reactions.Results: Management by CPS compared with other clinicians was associated with similar mean (SD) reductions of tobacco use (-7.9 [10.4] vs -5.4 [9.8] cigarettes per day, respectively; P = .15) and rates of complete abstinence (34% vs 38%, respectively; P = .73) and higher adherence (42% vs 31%, respectively; P = .01). Mean (SD) time to first follow-up was shorter for patients in the CPS group: 52 (66) vs 163 (110) days; P < .001. Adverse events were more common in the CPS group compared with the other clinicians group (42% vs 23%; P = .02).
Conclusions: These results suggest that CPS management of varenicline is as safe and effective as management by other clinicians. Additional research is needed to fully characterize the impact of pharmacist management of varenicline, justify expansion of CPS scope of practice, and ultimately enhance patient outcomes regarding tobacco cessation.
Discussion
The results of this single center study suggest that management of varenicline by CPSs is associated with similar reductions in tobacco use and abstinence rates compared with management by other clinicians. These results provide evidence that CPS management of varenicline may be as safe and effective as management by other clinicians.
Adherence rates (reported as proportion of days covered when assessing varenicline refill data) were higher on average among patients managed by a CPS compared with patients managed by other clinicians. However, this outcome may not be as reflective of adherence as initially intended, given delays in follow-up (see limitations section). Time to first follow-up was drastically different between the groups, with much sooner follow-up by CPSs compared with other clinicians. Despite similar tobacco cessation rates between groups, more frequent follow-up by CPSs helps to assess patient barriers to cessation, adherence to therapy, and AEs with varenicline. A higher percentage of AEs were documented within the CPS group that could be attributed to disparities in documentation rather than true rates of AEs. While rates of AEs were initially intended to serve as the primary safety outcome, they may instead reflect pharmacists’ diligence in monitoring and documenting tolerability of medication therapy.
Limitations
Several limitations to this study should be noted. First, the data collected were only as detailed as the extent to which prescribers documented tobacco use, previous cessation trials, and AEs; thus, various data points are likely missing within this study that could impact the results presented. In line with lack of documentation, delays in follow-up (ie, annual primary care visits) sorely undermined proportion of days covered, making these data less indicative of true medication adherence. Furthermore, this study did not account for concurrent therapies, such as combination varenicline and nicotine gum/lozenges, or behavioral treatment strategies like cessation classes.
Another limitation was that some primary care practitioners prescribed varenicline but then referred these patients to a CPS for tobacco cessation follow-up. Per the study’s protocol, these patients were included within the other clinician group, which could have brought results closer to the null. Finally, the timing of this chart review (July 1, 2019, to July 31, 2020) intersects with the start of the COVID-19 pandemic, presenting a possible confounding factor if patients’ quit attempts were hindered by the stress and isolation of the pandemic.19 All pharmacist visits during the pandemic were conducted by telephone, which may have affected results.
Conclusions
In this study of veterans receiving varenicline, management by CPSs resulted in similar reductions of tobacco use and rates of complete abstinence compared with management by other clinicians. Pharmacist management was associated with greater adherence and shorter time to first follow-up compared with other clinicians. Additional research is needed to fully characterize the impact of pharmacist management of varenicline, justify expansion of clinical pharmacist scope of practice, and ultimately enhance patient outcomes regarding tobacco cessation.
It would be interesting to see more studies outside of the VA system to determine the impact of pharmacist management of varenicline for a more heterogenous patient population. At some point, a prospective controlled trial should be conducted to overcome the various confounding factors that limit the results of retrospective chart reviews
