Depression care trajectories and associations with subsequent depressive episode: a registry-based cohort study (The Norwegian GP-DEP study).

Abstract

Background: Depression often has a recurrent course, but knowledge about the impact of treatment trajectories is scarce. We aimed to estimate treatment trajectories for patients with recurrent depression, and to explore associations between the trajectories and subsequent depressive episodes.

Methods: Cohort study based on linked registry data, comprising all Norwegian residents ≥ 18 years with an (index) depressive episode in 2012 following previous episode(s) in 2008-2011. We generated multi-trajectories based on treatment during index episode including GP follow-up consultation(s), long consultation(s) and/or talking therapy (with GP), antidepressants, and contact(s) with specialist care. Generalized linear models were used to analyse associations between different treatment trajectories and subsequent depression within one year.

Results: The study population consisted of 9 027 patients, mean age 44.6 years, 63.9% women. Five treatment trajectory groups were identified: "GP 1 month" (45.2% of the patients), "GP 6 months" (31.9%), "GP 12 months" (9.3%), "Antidepressants 12 months" (9.0%), and"Specialist 12 months" (4.6%). In group"GP 1 month" (reference), 25.1% had subsequent depression. While trajectory group "Antidepressants 12 months", had similar likelihood of subsequent depression as the reference (Relative risk (RR) = 1.04, 95% confidence interval (CI) 0.91-1.18), the groups "GP 12 months" (RR = 1.43, CI 1.28-1.59), "Specialist 12 months" (RR = 1.26, CI 1.08-1.47) and "GP 6 months" (RR = 1.17, CI 1.07-1.26) had increased risk of subsequent depression.

Conclusions: Our findings suggest that long-term antidepressant treatment of patients with recurrent depressive episodes may prevent subsequent depression episodes. However, this finding needs to be confirmed through studies that take into account the severity of depression.