Duration of untreated illness and clinical correlates in first-episode and drug-naïve patients with major depressive disorder

The notion that a prolonged duration of untreated illness (DUI) leads to poorer outcomes has contributed to extensive changes in mental health services worldwide. However, most studies on DUI have focused on schizophrenia and related psychosis. This study aimed to assess the possible relationship between DUI and certain clinical correlates in first-episode and drug-naïve patients with major depressive disorder (MDD).This cross-sectional study recruited 1718 first-episode and drug-naïve MDD outpatients. All participants were scored on the Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Positive and Negative Syndrome Scale, and thyroid hormone and metabolic parameters were measured. We used the Structure Clinical Interview for DSM-IV for clinical diagnosis and investigated suicide attempts through face-to-face interviews.A total of 171 (10%) of MDD patients had co-morbid psychiatric symptoms. Participants who were older, with lower education level, and married were less likely to seek a timely treatment compared to the counterparts. One-month longer untreated duration was associated with 2% to 9% higher odds of being with most of the investigated clinical conditions. For those with the longest DUI, the risk was increased for most of the investigated clinical conditions, with absolute risk differences ranging from 5.19% to 29.48%.These findings suggest that longer DUI may be negatively associated with clinical correlates in MDD. Further long-term follow-up studies are warranted to confirm these preliminary results.