Outcomes among Patients with Comorbid Substance Use and Depression in Integrated Care

Researchers with Seattle Pacific University examined the role of comorbid substance abuse and depression as associated with primary care and behavioral health clinical appointments. Study data was extracted from 224 randomly selected primary care patients from three integrated primary care clinics from one health care agency in the Pacific Northwest.

Three main analyses were conducted to examine the role of comorbid substance abuse and depression on health care utilization.

  • First, researchers examined primary care utilization. They found that primary care patients with substance use disorders had an increased number of primary care visits compared to non-substance abuse patients. However, this association was not significant among patients with depression. Additionally, researchers found no significant association between an interaction term of substance abuse and depression as associated with primary care visits.
  • Second, researchers examined behavioral health utilization. They found that substance abuse alone was not significantly associated with behavioral health visits. However, patients with depression had a significant increase in the number of behavioral health visits. Additionally, the interaction term between depression and substance abuse was significantly associated with behavioral health visits, meaning that patients with comorbid conditions were even more likely to have increased behavioral health visits than either condition alone.
  • Finally, researchers examined the moderating and mediating relation of depression on medical treatment utilization. They employed a bootstrapping technique along with an SPSS tool to quantify these potential pathways. Results indicated that depression moderates the association between substance use and behavioral health service while behavioral health services mediate the association between substance use disorders and medical treatment utilization.

The study has several limitations.

  • First, researchers were able to extract only a limited amount of demographic and diagnostic variables. Therefore, it is plausible that study findings are confounded by missing data elements such as patient demographics and clinical measures.
  • Second, research included a binary measure of substance abuse and depression, rather than a quantification of severity. Future research would benefit from discriminating levels of depression and substance abuse severity.
  •  Finally, the study was unable to include control subjects. Future research may want to examine if these associations are significant among patients seeking care in nonintegrated primary care settings or among control patients within the same study sites.

Read the related abstract.