Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Epidemiology and Biostatistics


MacDougall, Arlene G.

2nd Supervisor

Vingilis, Evelyn



Collaborative care is a model of care developed to treat common mental disorders, such as PTSD, in primary care. Objectives: conduct a meta-analysis to assess the effectiveness of collaborative care in treating PTSD and depression, as compared to usual care. Methods: Seven databases were searched for qualifying studies. Randomized controlled trials (RCTs) that compared collaborative care to usual care and reported PTSD outcomes continuous scales were included. Meta-analyses were conducted for PTSD and depression symptoms among people with PTSD. Results: 12 studies were included. Collaborative care was more effective than usual care at improving both PTSD (SMD= – 0.15; 95% CI: –0.31, –0.01), and depression (SMD= –0.16; 95% CI: –0.30, –0.03). Conclusion: Although a statistically significant difference between collaborative care and usual care was indicated, the difference was small and not necessarily clinically significant. More research is needed on the various components of collaborative care and how implementation of the model affects outcomes.

Summary for Lay Audience

Exposure to trauma elicits negative physical and emotional responses in individuals. Some individuals experience a longer lasting and heightened period of negative responses, known as post-traumatic stress disorder (PTSD). Depression commonly occurs alongside PTSD. Effective evidence-based treatments, such as medication and psychotherapy, for PTSD exist, but barriers and a lack of availability of specialist mental health care can make accessing treatment difficult. Collaborative care is a type of integrated care developed to treat mental disorders in a primary care setting. Collaborative care incorporates components that work together to improve care. This systematic review investigates the effectiveness of collaborative care on PTSD. Objectives were: (i) to describe the characteristics of each study’s collaborative care model; (ii) summarize their findings; and (iii) synthesize the evidence about collaborative care’s effectiveness in treating PTSD. A secondary objective was to determine the effectiveness of collaborative care in treating depression within the same population of patients. Seven online databases were searched. Studies were included if they were randomized controlled trials (RCTs), with patients of any age who were receiving an intervention described as collaborative care for mental health conditions or met the following criteria: had a multi-professional care team comprised of a primary care provider, and a mental health provider; a structured treatment plan; and evidence of enhanced inter-professional communication between members of the care team. Outcomes had to include a PTSD symptom outcome measured on a continuous scale. Characteristics of the interventions were narratively synthesized. Quantitative data were synthesized through random effects meta-analysis. Twelve studies involving 3,480 participants met the inclusion criteria. The characteristics of the studies’ samples varied considerably. Descriptions of the intervention varied significantly between studies and were reported with differing levels of detail. The meta-analysis on PTSD symptoms showed that collaborative care was significantly more iii effective than usual care at reducing symptoms. Collaborative care was also significantly more effective than usual care at reducing depressive symptoms. Although the meta-analyses showed evidence that collaborative care is more effective than usual care at reducing PTSD and depression symptoms, more research is needed to determine what components of the model affect outcomes.

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Available for download on Wednesday, December 31, 2025