Consideration of sex in clinical trials of transdermal nicotine patch: a systematic review.

Transdermal nicotine patch (TNP) is 1 of the most commonly used smoking cessation treatments; however, the efficacy of TNP by sex is not yet clear. The purpose of the current review was to synthesize how sex has been considered in published clinical trials of TNP for smoking cessation. The specific aims of the study were to examine the inclusion of sex in analyses of cessation outcomes, TNP-related variables (compliance, side effects), and quit-related variables (withdrawal, cravings); to review the consideration of sex-related variables (menstrual cycle phase, pregnancy); and to identify needs for future research. Potential articles published through December 31, 2013 were identified through a MEDLINE search of the terms "clinical trial," "nicotine patch," and "smoking cessation." Forty-two studies used all 3 terms and met the inclusion criteria. Approximately half of the studies reported that they considered sex in smoking cessation outcomes, with 15 studies finding no difference by sex and 7 studies finding better outcomes for men versus women. Only 5 studies reported data on outcomes by sex in their publications. No studies reported analysis of TNP compliance or withdrawal by sex. In the 1 study that examined side effects by sex, more women than men reported discontinuing TNP because of skin irritation. No study examined the association of cessation outcomes with menstrual cycle phase. There is a need to include sex in research on TNP, as well as other pharmacological and behavioral smoking treatments, to clarify the picture of treatment efficacy for women compared with men.