Referral for substance abuse treatment and depression improvement among patients with co-occurring disorders seeking behavioral health services in primary care

This study examined the relationship between substance treatment referrals and depression improvement among 2,373 participants with concurrent substance use and depressive disorders enrolled in an integrated behavioral health program. Three groups of substance treatment referral status were identified: accessed treatment (n = 780), declined treatment (n = 315), and no referral for treatment (n = 1278). The primary outcome is improvement in depressive symptoms (PHQ-9 < 10 or ≥ 50% reduction). Using propensity score adjustments, patients accessing substance treatment were significantly more likely to achieve depression improvement than those who declined receiving treatment services (hazard ratio (HR) = 1.82, 95% confidence interval (CI): 1.50–2.20, p < 0.001) and those without a referral for treatment (HR = 1.13, 95% CI: 1.03–1.25, p = 0.014). Each 1 week delay in initiating a referral was associated with a decreased likelihood of depression improvement (HR = 0.97, 95% CI: 0.96–0.98, p < 0.001). Study findings highlight the need of enhancing early treatment contact for co-occurring substance use disorders in primary care.