Impact of health system engagement on the health and well-being of people who use drugs: findings from a realist review

Health system engagement refers to patient and community involvement in health system planning, delivery, improvement, and scholarship. People who use drugs (PWUD) partner with the health system to improve care delivery for many reasons. PWUD may benefit individually, but may also experience harm. Our objective was to uncover why, how, and under what circumstances positive and negative health outcomes occur during health system engagement by PWUD. We conducted a realist review using five steps: (i) clarifying scope, (ii) searching for evidence, (iii) appraising studies and extracting data, (iv) synthesizing evidence, and (v) disseminating, implementing, and evaluating recommendations. Lived experience, clinician, and academic experts defined the explanatory model (program theory) of health within PWUD-partnered activities. The model was initially developed during scope clarification, then iteratively refined using formal theories, 85 empirical publications, and team discussion. Health system engagement can be transformative. It must also include meaningful social and structural support, clear role definition, cultural safety, and opportunity for personal development. Best practices include fair compensation, clear role descriptions, psychological and cultural support, continuous learning, and meaningful input into key decisions. Engagement experiences can be health-promoting or health-threatening for PWUD. Health system actors should develop and action health-promoting policies when partnering with PWUD.