Which somatic symptoms are associated with an unfavorable course in Chinese patients with major depressive disorder?

Introduction: This was an analysis of the impact of somatic symptoms on the severity and course of depression in Chinese patients treated for an acute episode of major depressive disorder (MDD). Methods: Data were extracted from a 3-month prospective observational study which enrolled 909 patients with MDD in psychiatric care settings; this analysis focused on the Chinese patients (n = 300). Depression severity was assessed using the Clinical Global Impression of Severity (CGI-S) and 17-item Hamilton Depression Rating Scale (HAMD-17); somatic symptoms were assessed using the patient-rated 28-item Somatic Symptom Inventory (SSI). Cluster analysis using baseline SSI scores grouped patients into three clusters with no/mild, moderate, or severe somatic symptoms. Four SSI factors (pain, autonomic symptoms, energy, and central nervous system) were defined, and regression analyses identified which factors were associated with remission at 3 months. Results: More than 70% of the patients had moderate or severe somatic symptoms. Baseline depression severity (HAMD-17 and CGI-S scores) was associated with more severe somatic symptoms. Remission rates differed between clusters of patients: 84.1%, 72.0%, and 55.3% for no/mild, moderate, and severe somatic symptoms, respectively (P = 0.0034). Pain symptoms were the somatic symptoms more strongly associated with lower remission rates at 3 months. Discussion: Somatic symptoms are associated with greater clinical severity and lower remission rates. Among somatic symptoms, pain symptoms have the greatest prognostic value and should be taken into account when treating patients with depression.