Abstract
OBJECTIVE: The authors investigated whether quality improvement programs for depression would be effective among substance misusers and whether there would be a differential program-by-comorbidity effect.
METHOD: A group-level randomized controlled trial (Partners in Care) compared two quality improvement programs for depression with usual care. Consecutive patients (N=27,332) from six managed care organizations in five states were screened, and 1,356 were enrolled: 443 received usual care while the rest entered a quality improvement program involving either medication (N=424) or therapy (N=489). Multiple logistic regression was used to test hypotheses and compute standardized predictions of the adjusted rates of depression and use of psychotherapy and antidepressants.
RESULTS: Under usual care conditions, depressed patients with substance misuse had an increased probability of ongoing depression despite higher rates of overall appropriate treatment. Among clients with comorbid substance misuse, the quality improvement programs were associated with improved depression outcomes at 12 months and increased antidepressant use at 6 months. Among clients with no substance misuse, the quality improvement programs improved depression outcomes at 6 months and were associated with increased treatment utilization.
CONCLUSIONS: Co-occurring substance misuse is associated with depression and with increased risk for poorer depression treatment outcomes under usual care conditions. Quality improvement programs can significantly reduce the likelihood of probable depressive disorders in depressed patients with and without comorbid substance misuse. No consistent evidence was found for a differential program-by-comorbidity effect except for a suggestion of greater increase in psychotherapy among individuals with no substance misuse.
Substance misuse is common among people with depressive disorders, and the co-occurrence of substance misuse and depression is associated with greater impairment and worse treatment outcomes than in individuals with either disorder alone. National data suggest that among individuals with an episode of major depression in the past year, 21% had an alcohol use disorder and 9% had a drug use disorder; many more have substance misuse but not abuse or dependence. Among primary care patients with depression, more than one-quarter report substance misuse; some of these have abuse or dependence. The quality of care for co-occurring disorders is low, and the majority of people with co-occurring disorders do not receive either mental health or substance abuse care.
The quality of care for depressive disorders can be improved by practice-based quality improvement interventions that lead to increased rates of treatment and improved clinical outcomes. These interventions work in primary care settings among clients with and without comorbid medical illnesses and among men and women, but it is not known whether such programs are effective for individuals with depression and substance misuse.
There are several reasons to suspect that a quality improvement intervention might have a different effect among individuals with co-occurring substance misuse. The presence of comorbid substance misuse complicates the diagnosis and treatment of depression, with some experts recommending psychotherapy and a period of abstinence before initiating pharmacotherapy, whereas others offer antidepressant treatment to clients even when substance use is ongoing. Treatments for depression are thought to be less effective among substance users, although some studies suggest that treatment is effective even among those who use alcohol or other drugs. Patterns of care may also differ, since 1) providers may be more likely to provide psychotherapy than medication to depressed patients with co-occurring substance misuse, and 2) behavioral treatments carry little or no risk to the patient and can be initiated early in treatment when a formal diagnosis of depression is still uncertain.
We used data from the Partners in Care trial to investigate whether quality improvement programs for depression would be effective among substance misusers. We hypothesized that 1) under usual care conditions, depressed primary care patients with comorbid substance misuse would have a higher probability of ongoing depression, lower rates of antidepressant use and overall appropriate treatment, and higher rates of psychotherapy at 6 and 12 months than patients without comorbid substance misuse; and 2) quality improvement programs for depression would be effective among substance abusers as well as nonusers and would improve rates of overall appropriate treatment.
Study Design
Partners in Care was a group-level, randomized controlled trial involving six managed care organizations in five states that compared two quality improvement programs for depression with usual care. It included staff and network model multispecialty group practices and rural managed public health clinics; patients had prepaid or managed fee-for-service coverage. Clinics were selected to oversample Mexican Americans and to be diverse in geography and organization. Forty-six of 48 primary care clinics participated, and 181 of 183 primary care providers agreed to participate. Forty-six clinics were grouped into nine blocks of three clinic clusters each, matched for patient demographics, clinician specialty, and proximity to a mental health provider. Within each block, clinics were randomly assigned to provide usual care or one of two quality improvement interventions (medication or therapy).
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Katherine E. Watkins, M.D., M.S.H.S., Susan M. Paddock, Ph.D., Lily Zhang, M.S., and Kenneth B. Wells, M.D., M.P.H.
Am J Psychiatry 163:125-132, January 2006
doi: 10.1176/appi.ajp.163.1.125
