The study in the Journal of the American Medical Association suggested that smokers who failed to quit with varenicline in the trial’s first phase were seven times more likely to quit by the end of the second phase if varenicline doses were increased.
Success also was increased twofold if patients were switched from a CNRT regimen to varenicline, according to University of Texas MD Anderson Cancer Center researchers.
The authors noted that the chance of abstinence was near zero in patients who were switched from varenicline to CRNT or who remained on the same treatment plans.
“These data indicate that sticking to the same medication isn't effective for smokers who are unable to quit in the first six weeks of treatment,” explained lead researcher Paul Cinciripini, PhD, chair of behavioral science. “Our study should encourage doctors to check in on patients early in their cessation journey and, if patients are struggling, to try a new approach, such as increasing medication dosage.”
The study pointed out that most people who smoke do not quit on their initial attempt; that led investigators to attempt to determine the best subsequent strategy for nonabstinence following initial treatment with varenicline or CNRT.
The study team used a double-blind, placebo-controlled, sequential multiple assignment randomized trial that included 490 volunteers who were randomized to receive 6 weeks of varenicline or CNRT. After 6 weeks, nonabstainers were rerandomized to continue, switch, or increase medication dosage for 6 additional weeks in the study, which was conducted from June 2015 through October 2019 in a Texas tobacco treatment clinic.
The initial treatment was 2 mg/day of varenicline or the combined replacement therapy of a 21-mg patch plus a 2-mg lozenge. In addition to brief weekly counseling, the rerandomized participants either continued with their initial therapies, switched between varenicline and CNRT, or increased dosages either to 3 mg or more of varenicline or a 42-mg patch and lozenges. The main outcome was defined as biochemically verified 7-day point prevalence abstinence at the end of treatment at 12 weeks.
The participants had smoked an average of 20 cigarettes per day; however, after the first phase, 54 participants in the CNRT group were abstinent and continued his or her therapy. Of the 191 who were not abstinent, 151 were rerandomized, and the 40 who did not return for rerandomization were assigned to continue their initial CNRT condition in phase II.
The results indicated that the end-of-treatment abstinence rate for the 191 phase I nonabstainers was 8% (95% credible interval [CrI], 6%-10%) for the 90 (47%) who continued at the dosage condition; 14% (CrI, 10%-18%) for the 50 (33%) who increased their dosage; and 14% (95% CrI, 10%-18%) for the 51 (34%) who switched to varenicline (absolute risk difference [aRD], 6%; 95% CrI, 6%-11%), with more than 99% posterior probability that either strategy conferred benefit over continuing the initial dosage.
“After the first phase, 88 participants in the varenicline group were abstinent and continued their therapy; of the 157 who were not abstinent, 122 were rerandomized, and 35 who did not return for rerandomization were assigned to continue with the varenicline condition,” the researchers explained. “The end-of-treatment abstinence rate for the 157 phase I nonabstainers was 20% (95% CrI, 16% to 26%) for the 39 (32%) who increased their varenicline dosage, 0 (95% CrI, 0 to 0) for the 41 (34%) who switched CNRT, and 3% (95% CrI, 1% to 4%) for the 77 (49%) who were assigned to the continued varenicline condition (aRD, –3%; 95% CrI, –4% to –1%) with more than 99% posterior probability that continuing varenicline at the initial dosage was worse than switching to a higher dosage.”
The study team pointed out that increasing the varenicline dosage had an aRD of 18% (95% CrI, 13%-24%) and a more than 99% posterior probability of conferring benefit. Looking at the secondary outcome of continuous abstinence at 6 months, the researchers noted that only increased dosages of the CNRT and varenicline provided benefit over continuation of the initial treatment dosages.
“For individuals who smoked but did not achieve abstinence after treatment with varenicline, increasing the dosage enhanced abstinence vs continuing, whereas for nonabstainers initially treated with CNRT, a dosage increase or switch to varenicline enhanced abstinence and may be viable rescue strategies,” the authors concluded.
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