Effect of smoking habits and concomitant valproic acid use on relapse in patients with treatment-resistant schizophrenia receiving clozapine: A 1-year retrospective cohort study.

The findings suggest that the combination of smoking habits and concomitant VPA use may increase the risk of relapse after discharge. Future studies are required to elucidate the mechanisms underlying these findings, such as a decrease in clozapine blood levels.