Objective: This study aimed to explore treatment outcomes and pharmacological treatment intensities across major depressive disorder (MDD) subtypes over a 24-month period in a naturalistic clinical setting.
Methods: A total of 1079 MDD patients were classified into melancholic (N=182; 16.9%), atypical (N=68; 6.3%), and unspecified (N=829; 76.8%) subtypes and followed in a longitudinal cohort study. Treatment intensity and outcomes, including 12-week and 12-month remission and 24-month relapse rates, were measured using the Hamilton Depression Rating Scale (HAMD).
Results: There were no significant differences in remission or relapse rates across subtypes at 12 weeks, 12 months, or 24 months. However, melancholic and atypical subtypes received more intensive pharmacological treatments compared to the unspecified subtype, particularly during the initial 12-week treatment phase. This increased treatment intensity was associated with equivalent outcomes across subtypes.
Conclusion: Despite similar long-term outcomes across MDD subtypes, variations in treatment intensity were crucial for achieving these results. Our findings suggest that tailoring treatment plans according to depressive subtype severity and characteristics is essential for effective management. Future research should investigate the genetic and biomolecular bases of these subtypes to further optimize treatment strategies.