Introduction
REGRESSION, REGRESSIONS
Many people who smoke state that they want to quit,A recent Cochrane systematic reviewRandomly assigning people to continue or quit smoking is not feasible; therefore, observational methods are the only way to study the association between smoking cessation and mental health. However, traditional observational epidemiology has a primary issue: determining whether associations are causal. One concern is reverse causality (ie, improved mental health may make successful quitting more likely). A systematic reviewThis study used 3 confirmatory coprimary analyses—multivariable regression models, propensity score–adjusted models, and instrumental variable (IV) regressions—to evaluate the association between smoking cessation and mental health outcomes. The multivariable regression model will have the least control for confounding, propensity score–adjusted modeling will have less susceptibility,