Inequity in smoking cessation clinical trials testing pharmacotherapies: exclusion of smokers with mental health disorders

OBJECTIVES: People suffering from mental health disorder (MHDs) are often under-represented in clinical research though the reasons for their exclusion are rarely recorded. As they have higher rates of smoking and nicotine dependence, it is crucial that they are adequately represented in clinical trials of established pharmacotherapy interventions for smoking cessation. This review aims to examine the practice of excluding smokers with MHDs and reasons for such exclusion in clinical trials evaluating pharmacotherapy treatments for smoking cessation. DATA SOURCE: The Cochrane database of systematic reviews was searched until September 2020 for reviews on smoking cessation using pharmacotherapies. STUDY SELECTION: Randomised controlled trials (RCTs) within the selected Cochrane reviews were included. DATA EXTRACTION: Conducted by one author and independently verified by three authors. DATA SYNTHESIS: We included 279 RCTs from 13 Cochrane reviews. Of all studies, 51 (18.3%) explicitly excluded participants with any MHDs, 152 (54.5%) conditionally excluded based on certain MHD criteria and 76 (27.2%) provided insufficient information to ascertain either inclusion or exclusion. Studies of antidepressant medications used for smoking cessation were found to be 3.33 times more likely (95% CI 1.38 to 8.01, p=0.007) to conditionally exclude smokers with MHDs than explicitly exclude compared with studies of nicotine replacement therapy. CONCLUSION: Smokers with MHDs are not sufficiently represented in RCTs examining the safety and effectiveness of smoking cessation medications. Greater access to clinical trial participation needs to be facilitated for this group to better address access to appropriate pharmacotherapeutic interventions in this vulnerable population.