First-month Intensity of Collaborative Care and Patient Depression Outcomes
Collaborative care is a prominent, evidence-based delivery model for integrating behavioral health care in primary care settings. A key element of the model is systematic follow-up with patients for treatment monitoring and adjustment. This study aims to assess whether greater intensity of follow-up in the first month of collaborative care changes the trajectories of patient depression outcomes over one year. Findings of this study will inform the design of performance standards and evaluations in collaborative care implementation.
Study Design:
We used data from the intervention arm of a large randomized trial of collaborative care known as IMPACT. First-month intensity was measured by a) having >=1 follow-up visit to the care manager (in-person or telephonic) within 2 weeks of treatment initiation and b) having >= 2 follow-up visits within the first 4 weeks. Depression outcomes included 1) Symptom Checklist (SCL) scores based on research interviews, assessed at 3-, 6-, and 12- month, and 2) time to remission of depressive symptoms based on Patient Health Questionnaire (PHQ)-9 assessed during care management visits. Statistical analysis involved mixed-effects models for the longitudinal SCL scores and Kaplan-Meier product-limit estimation and Cox proportional hazard models for time to remission. In each analysis, one of the two intensity measures was used as the key independent variable at a time.
Population Studied:
Primary care patients 65 years or older who met clinical diagnostic criteria for major depression or dysthymia, were initiated into collaborative care (>=1 visit to care manager) and had a PHQ-9 score >=5 at the first visit.
Principal Findings:
Having >=1 follow-up visit within 2 weeks was associated with a reduction in SCL score of .09 at 3-month (p=0.110), 0.1 at 6-month (p=0.082), and .06 at 12-month (p=0.250). Having >=2 follow-up visits within 4 weeks was associated with a reduction in SCL score of .06 at 3-month (p=0.279), 0.13 at 6-month (p=0.011), and 0.11 at 12 months (p=0.036); reduction at 6- and 12-month was equivalent to ¼ - ½ of the effect size of the collaborative care intervention estimated from the IMPACT study. The 2-week intensity measure was associated with a median time to remission of 70 days vs. 91 days (p=0.026), and a hazard ratio of remission of 1.25 (p=0.028). The 4-week intensity measure was associated with a median time to remission of 71 days vs. 85 days (p=0.029), and a hazard ratio of 1.26 (p=0.018).
Conclusions:
Greater intensity of follow-up in the first month of collaborative care was associated with improved depressive symptoms at 6- and 12- month and a substantially shorter time to remission.
Implications for Policy, Delivery or Practice:
Intensive follow up in the early stage of collaborative care is an important and easily measurable feature of the evidence-based model. Our findings support the use of first-month intensity measures when setting standards and measuring and rewarding performances for implementation initiatives of collaborative care.