Background: Detection rates of depression in primary care are <50%. Studies showed similar outcome after 12 months for recognized and unrecognized depression. Outcome beyond 12 months is less well studied.
Objective: We investigated recognition of depression in primary care and its relation to outcome after 6, 12 and 39 months.
Methods: Data were used from a prospective cohort study of 1293 consecutive general practice attendees (PREDICT-NL), who were followed up after 6 (n = 1236), 12 (n = 1179) and 39 (n = 752) months. We measured the presence and severity of major depressive disorder (MDD) according to DSM-IV criteria and Patient Health Questionnaire 9 (PHQ-9) and mental function with Short Form 12 (SF-12). Recognition of depression was assessed using international classification of primary care codes (P03 and P76) and Anatomical Therapeutic Chemical (N06A) codes from the GP records (6 months before/after baseline).
Results: At baseline, 170 (13%) of the participants had MDD, of whom 36% were recognized by their GP. The relative risk of being depressed after 39 months was 1.35 [95% confidence interval (CI) 0.7-2.7] for participants with recognized depression compared to unrecognized depression. At baseline, participants with recognized depression had more depressive symptoms (mean difference PHQ-9 2.7, 95% CI 1.6-3.9) and worse mental function (mean difference mental component summary -3.8, 95% CI -7.8 to 0.2) than unrecognized depressed participants. After 12 and 39 months, mean scores for both groups did not differ but were worse than those without depression.
Conclusions: A minority of patients with MDD is recognized in primary care. Those who were unrecognized had comparable outcome after 12 and 39 months as participants with recognized depression.