Objective  To investigate the changes in social function impairment and quality of life and their predictive factors in patients with major depressive disorder (MDD) over the course of 1-year drug treatment.

  Methods  A total of 54 MDD patients were enrolled for the study. The 17-item Hamilton Rating Scale for Depression (HAMD-17, hereafter referred to simply as HAMD), Sheehan Disability Scale (SDS), and Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF) were used to evaluate depressive symptoms, social functioning, and quality of life, respectively, at baseline (0), as well as 1 month (1 m), 2 months (2 m), 3 months (3 m), 6 months (6 m), 9 months (9 m), and 12 months (12 m) after medication started. The symptoms and the recovery of social function at different time points was analyzed, and correlation analysis and regression analysis were done to explore the influencing factors of functional recovery.

  Results  Among the 54 MDD patients, 27 completed the 12-month follow-up, and 2 patients relapsed at 12 m. The total baseline score of SDS (SDS₀) in MDD patients was higher than that in healthy controls (t=12.161, P<0.001), and the baseline score of Q-LES-Q-SF (Q-LES-Q-SF₀) was lower than that in the controls (t=12.260, P<0.001). Comparison of the HAMD score, SDS total score and the factor scores, and Q-LES-Q-SF total scores of the MDD patients at different time points showed significant differences, presenting an F value of 65.987, 28.944, 23.589, 27.070 and 28.668, respectively (all P<0.001). HAMD₀ was negatively correlated with age. The HAMD score was positively correlated with SDS score of the same time point and negatively correlated with Q-LES-Q-SF score of the same time point. At 3 m, the change in HAMD score (HAMD_{3 m-0}) was positively correlated with the change in SDS score (SDS_{3 m-0}) and negatively correlated with the change in Q-LES-Q-SF score (Q-LES-Q_{3 m-0}). At 12 m, the change in HAMD score (HAMD_{12 m-0}) was positively correlated with the change in SDS score (SDS_{12 m-0}) and negatively correlated with the change in Q-LES-Q-SF score (Q-LES-Q_{12 m-0}). Regression analysis revealed that SDS₀ and Q-LES-Q₀ could be used to predict SDS_{3 m-0}, R²=0.391, while SDS₀ and full-time employment status could be used to predict SDS_{12 m-0}, R²=0.640. Q-LES-Q₀ could be used to predict Q-LES-Q_{3 m-0}, R²=0.294, while Q-LES-Q₀ and full-time employment status could be used to predict Q-LES-Q_{12 m-0}, R²=0.591.

  Conclusion  Long-term regular medication can improve social dysfunction in patients with MDD and symptom relief is the basis for improvement of social function level and quality of life, while increasing employment saturability to some extent may help improve the long-term social function and quality of life.