Disparities in the prevalence of cigarette smoking among bisexual people: a systematic review, meta-analysis and meta-regression.

OBJECTIVE: To review the bisexual-specific prevalence and likelihood of cigarette smoking relative to lesbian/gay and heterosexual individuals. DATA SOURCES: We searched MEDLINE, PsycInfo, CINAHL, Scopus and LGBT Life databases (from 1995 to September 2019) for studies reporting cigarette smoking among bisexuals versus their comparators. STUDY SELECTION: Observational, quantitative, peer-reviewed studies providing estimates for lifetime, past 30 days or current cigarette smoking among bisexuals and any of the two comparators were selected. DATA EXTRACTION: Data on sexual orientation groups, cigarette smoking, sample type and mechanism, data collection mode, country and median year, as well as gender and age groups were extracted. DATA SYNTHESIS: Random-effects meta-analysis was used to estimate the pooled OR (95% CIs) of cigarette smoking. Meta-regression was used to examine the difference in the prevalence of cigarette smoking by study and sample characteristics. Of 4663 unduplicated records, 47 unique studies were included (14, 23 and 22 studies on lifetime, past 30 days and current cigarette smoking, respectively). Compared with lesbians/gays and heterosexuals, bisexuals were 1.25 (1.15 to 1.37) and 2.18 (1.84 to 2.59) times more likely to report lifetime smoking, 1.17 (1.08 to 1.27) and 2.49 (2.20 to 2.83) times more likely to report past 30 days smoking and 1.19 (1.00 to 1.43) and 2.26 (1.97 to 2.59) times more likely to report current smoking. Gender was a significant covariate in the meta-regression models. CONCLUSIONS: Cigarette smoking was more prevalent among bisexuals than lesbians/gays and heterosexuals, with the estimates showing a greater magnitude among bisexual women relative to all other sexual orientation/gender subgroups.