Efficacy of a flexible quit date versus an a priori quit date approach to smoking cessation: a cross-study analysis.

Most treatment guidelines recommend that smokers should set a target quit date (TQD) at treatment onset because making a public commitment to quit on a given date should increase motivation. On the other hand, allowing smokers the flexibility to choose when to stop after starting treatment might allow smokers to better tailor their quit date and might improve the acceptability of treatment among smokers not willing to set a TQD. In a recent placebo-controlled study, we found varenicline effective when smokers were not required to set a quit date a priori; i.e., with a "flexible quit date" (FQD) approach. The current analysis compares the effect sizes and quit rates in this FQD study with those of nine prior varenicline randomized controlled trials (RCTs) that used a TQD approach. The odds ratio for varenicline versus placebo in the FQD study was the 4th highest of the 10 trials and the incidence of continuous abstinence for varenicline was 5th highest. These results suggest that a FQD approach can produce quit rates similar to a TQD approach. Cross-study comparisons can have hidden bias; thus, a RCT of fixed versus flexible quit dates would provide a more valid test. Also, a study of whether different subpopulations of smokers may be more interested in or especially benefit from, one or the other approach to quitting is indicated.