Although mild to moderate major depressive disorder (MDD) is one of the main reasons for consulting a general practitioner (GP), there is still no international consensus on the most appropriate therapeutic approach.

The aim of this study is to evaluate the clinical effectiveness of watchful waiting (WW) compared with the use of antidepressants (ADs) for the treatment of mild to moderate depressive symptoms in 263 primary care (PC) usual-practice patients in a 12-month pragmatic non-randomised controlled trial. Both longitudinal and per-protocol analyses were performed, through a multilevel longitudinal analysis and a sensitivity analysis.

We observed a statistically significant time x treatment interaction in the severity of depression (Patient Health Questionnaire, PHQ-9) and disability (World Health Organization Disability Assessment Schedule, WHODAS) in favour of the AD group at 6 months but not at 12 months. The effect size of this difference was small. No statistically significant differences were observed between groups in severity of anxiety (Beck Anxiety Inventory, BAI) or health-related quality-of-life (EuroQol-5D, EQ-5D). Sensitivity analysis and per-protocol analysis showed no differences between the two groups in any of the evaluated scales.

Superiority of either treatment (WW and AD) was not demonstrated in patients treated for depression in PC after one year of follow-up.