We systematically reviewed implementation research targeting depression interventions in low- and middle-income countries (LMICs) to assess gaps in methodological coverage.

PubMed, CINAHL, PsycINFO, and EMBASE were searched for evaluations of depression interventions in LMICs reporting at least one implementation outcome published through March 2019.

A total of 8714 studies were screened, 759 were assessed for eligibility, and 79 studies met inclusion criteria. Common implementation outcomes reported were acceptability (n = 50; 63.3%), feasibility (n = 28; 35.4%), and fidelity (n = 18; 22.8%). Only four studies (5.1%) reported adoption or penetration, and three (3.8%) reported sustainability. The Sub-Saharan Africa region (n = 29; 36.7%) had the most studies. The majority of studies (n = 59; 74.7%) reported outcomes for a depression intervention implemented in pilot researcher-controlled settings. Studies commonly focused on Hybrid Type-1 effectiveness-implementation designs (n = 53; 67.1), followed by Hybrid Type-3 (n = 16; 20.3%). Only 21 studies (26.6%) tested an implementation strategy, with the most common being revising professional roles (n = 10; 47.6%). The most common intervention modality was individual psychotherapy (n = 30; 38.0%). Common study designs were mixed methods (n = 27; 34.2%), quasi-experimental uncontrolled pre-post (n = 17; 21.5%), and individual randomized trials (n = 16; 20.3).

Existing research has focused on early-stage implementation outcomes. Most studies have utilized Hybrid Type-1 designs, with the primary aim to test intervention effectiveness delivered in researcher-controlled settings. Future research should focus on testing and optimizing implementation strategies to promote scale-up of evidence-based depression interventions in routine care. These studies should use high-quality pragmatic designs and focus on later-stage implementation outcomes such as cost, penetration, and sustainability.