Assessment of Racial Differences in Pharmacotherapy Efficacy for Smoking Cessation: Secondary Analysis of the EAGLES Randomized Clinical Trial

IMPORTANCE: Understanding Black vs White differences in pharmacotherapy efficacy and the underlying reasons is critically important to reducing tobacco-related health disparities. OBJECTIVE: To compare pharmacotherapy efficacy and examine variables to explain Black vs White differences in smoking abstinence. DESIGN, SETTING, AND PARTICIPANTS: This study is a secondary analysis of the Evaluating Adverse Events in a Global Smoking Cessation Study (EAGLES) double-blind, placebo-controlled, randomized clinical trial, which took place at clinical trial centers, academic centers, and outpatient clinics in 29 states in the US. US Black and White smokers who smoked 10 or more cigarettes per day with and without psychiatric comorbidity were enrolled between November 2011 and January 2015. Data analysis was performed from July 2019 to January 2020. INTERVENTIONS: Participants were randomized (1:1:1:1) in a double-blind, triple-dummy, placebo- and active-controlled (nicotine patch) trial of varenicline and bupropion for 12 weeks with follow-up through week 24. MAIN OUTCOMES AND MEASURES: Biochemically verified continuous cigarette abstinence rate (CAR) from weeks 9 to 24. Baseline, postbaseline treatment, and safety characteristics were examined as variables to explain race differences in abstinence. RESULTS: Of the 1065 Black smokers enrolled, 255 were randomized to receive varenicline, 259 received bupropion, 286 received nicotine replacement therapy (NRT [ie, nicotine patch]), and 265 received placebo. Among the 3044 White smokers enrolled, 778 were randomized to receive varenicline, 769 received bupropion, 738 received NRT, and 759 received placebo. Participants were predominantly female (614 Black [57.7%] and 1786 White [58.7%] women) and heavy smokers (mean [SD] cigarettes per day, 18.2 [7.9] for Black and 20.0 [7.5] for White smokers), with a mean (SD) age of 47.2 (11.2) years for Black and 46.5 (12.7) years for White participants. Treatment and race were associated with CAR for weeks 9 to 24. The CAR was 4.9% lower for Black vs White participants (odds ratio [OR], 0.53; 95% CI, 0.41-0.69; P < .001); differences were found across all treatments. Pooling psychiatric and nonpsychiatric cohorts, varenicline (OR, 2.63; 95% CI, 1.90-3.63; P < .001), bupropion (OR, 1.75; 95% CI, 1.25-2.46; P = .001), and NRT (OR, 1.52; 95% CI, 1.07-2.16; P = .02) had greater efficacy than placebo for White participants. Only varenicline (OR, 2.63; 95% CI, 1.26-5.48; P = .01) had greater efficacy than placebo for Black participants. Baseline, postbaseline, and safety characteristics differed by race, but these variables did not eliminate the association of race with CAR. Black participants had 49% reduced odds of CAR for weeks 9 to 24 compared with White participants in the adjusted model (OR, 0.51; 95% CI, 0.39-0.66; P < .001). CONCLUSIONS AND RELEVANCE: Black and White smokers achieved the highest rate of abstinence while taking varenicline, suggesting that it is the best first-line therapy for these groups. However, Black smokers were less responsive to all therapies, including placebo. Understanding variables (eg, socioeconomic or biological) beyond those may lead to improved treatment outcomes for Black smokers. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01456936