Chronic pain and depression are highly comorbid, but the lack of consensus on the best treatment strategies puts patients at high risk of suboptimal care-coordination as well as health and social complications. Therefore, this study aims to quantitatively assesses how effective different primary care interventions have been in treating the comorbid state of chronic pain and depression. In particular, this study evaluates both short-term outcomes-based specifically on measures of chronic pain and depression during an intervention itself-and long-term outcomes or measures of pain and depression in the months after conclusion of the formal study intervention.
This study is a systematic review and meta-analysis of randomised-controlled trials (RCTs) enrolling patients with concurrent chronic pain and depression. Intensity and severity of pain and depression symptoms were the primary outcomes. The main inclusion criteria were RCTs that: (i) enrolled patients diagnosed with depression and chronic pain, (ii) occurred in primary care settings, (iii) reported baseline and post-intervention outcomes for chronic pain and depression, (iv) lasted at least 8 weeks, and (v) used clinically validated outcome measures. Risk of bias was appraised with the Risk of Bias 2 tool, and GRADE guidelines were used to evaluate the quality of evidence.
Of 692 screened citations, 7 multicomponent primary care interventions tested across 891 patients were included. Meta-analyses revealed significant improvements in depression at post-intervention (SMD = 0.44, 95% CI [0.17, 0.71], P = 0.0014) and follow-up (SMD = 0.41, 95% CI [0.01, 0.81], P = 0.0448). Non-significant effects were observed for chronic pain at post-intervention (SMD = 0.27, 95% CI [-0.08, 0.61], P = 0.1287) and follow-up (SMD = 0.13, 95% CI [-0.3, 0.56], P = 0.5432).
Based on the results of the meta-analysis, primary care interventions largely yielded small to moderate positive effects for depressive symptoms and no significant effects on pain. In one study, stepped-care to be more effective in treatment of comorbid chronic pain and depression than other interventions both during the intervention and upon post-intervention follow-up. As such, depression appears more amenable to treatment than pain, but the number of published RCTs assessing both conditions is limited. More research is needed to further develop optimal treatment strategies.

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