Objective:
The aim of this review was to clarify whether the effects of gender, medicine and having present diseases were associated with success of quitting smoking in the Japanese Smoking Cessation Treatment (SCT) program.

Methods:
A systematic search of four English electronic databases (Pubmed, CINAHL Plus, Scopus and Web of Science), two Japanese electronic databases (CiNii Articals and Ichushi), and additional search through references of previous papers were conducted to identify eligible studies. The search terms were: [‘factors’ or ‘predictors’] and [‘smoking cessation’ or ‘smoking cessation interventions’ or ‘quit smoking’ or ‘stop smoking’]. The terms of [‘Japan’ or ‘Japanese’] were further limited when the papers were searched in four English electronic databases. For meta-analysis, we used the software of Review Manager 5.3 to compute pooled effect estimates and a heterogeneity index I2. The meta-analysis results were reported as pooled OR (95% CI), with I2 and p-values.

Results:
Of 1079 identified studies, 30 studies (N=6389 people) were included in this review. Our study revealed that male (OR=1.61, 95% CI:1.35-1.92, I2=26%, p<0.001) , varenicline (OR=1.78, 95%CI: 1.46-2.18, I2=0%, p<0.001), and having mental disease (OR=0.34, 95%CI: 0.23-0.51, I2=45%, p<0.001) were associated with success in quitting smoking in the Japanese SCT program. Having present diseases (OR=0.68, 95% CI: 0.42-1.11, I2=70%, p=0.12) was not significantly associated with success of quitting smoking statistically.

Conclusions:
In the Japanese SCT program, male, varenicline and having mental diseases have been found to predict success in quitting smoking.