To analyze the independent effects and interaction of tobacco dependence level and depression on health related quality of life (HRQoL) among current smokers.

The data was from the 2021 “Psychology and Behavior Investigation of Chinese Residents” (RBICR) and a total of 1 399 cases were included in the analysis. Tobacco dependence level, depression, and HRQoL were assessed using the fagerstrom test for nicotine dependence scale, the patient health questionnaire-9 and the European five-dimensional five-level health scale. Mplus 7.0 and R software were used for analyses.

The latent class analysis supported low and high level tobacco dependence level, with mean health utility value of 1.00(0.95, 1.00) and 1.00(0.89, 1.00), respectively, and the difference was statistically significant (Z=-5.521, P<0.001). The mean health utility values of the depressed and non-depressed groups were 1.00(0.84, 1.00), 1.00(0.95, 1.00), and the difference was statistically significant (Z=-7.580, P<0.001). Tobit regression analysis found that tobacco dependence level (β=-0.030, 95% CI:-0.043~-0.018) and depression(β=-0.068, 95%CI: -0.083~-0.053) were negatively associated with health utility value. Interaction analysis found no multiplicative interactions between tobacco dependence level and depression on HRQoL (OR=1.039, 95% CI: 0.589-1.831). There was a additive interaction between tobacco dependence level and depression on HRQoL, with high levels of tobacco dependence and depression co-existing at a higher risk of unhealthiness than the two factors alone(RERI=1.411, 95% CI: 0.055-2.767), and the synergistic effect was 1.464 times greater than the sum of the effects of the two factors alone(SI=1.464, 95% CI: 0.990-2.163), and the proportion of all unhealthy smokers attributable to high levels of tobacco dependence with a synergistic effect of depression was 25.87%(AP=25.87%, 95% CI: 3.91%-47.82%). Sensitivity analysis found that AP and SI index increased.

Tobacco dependence level and depression were negatively associated with HRQoL, and there was an additive interaction on HRQoL. Reducing tobacco dependence level among current smokers, developing targeted smoking cessation interventions and preventing depressive symptoms are important for improving current smokers’ HRQoL.