IMPACT Collaborative Care for Late-Life Depression
University of Washington / RAND / multiple health systems · United States · 2002
Summary
The IMPACT trial is the landmark experiment in collaborative care for depression — a model that integrates mental health treatment into primary care rather than expecting patients to navigate a separate mental health system. The 115 additional depression-free days over two years represents a clinically meaningful difference: nearly four extra months free of depression. The model works because it removes the most common barrier to mental health treatment: access. Most people with depression see a primary care physician; almost none are successfully connected to a psychiatrist. IMPACT places the care manager in the primary care workflow, using outcome measurement and stepped care to ensure treatment escalates when it's needed. The experiment produced both clinical and economic evidence compelling enough to change Medicare reimbursement policy fifteen years later.
Research question
"Does a structured collaborative care model — integrating a depression care manager into primary care — improve depression outcomes compared to usual primary care?"
Methodology
Intervention
Patients with major depression or dysthymia in 18 primary care clinics randomly assigned to: (a) collaborative care — primary care physician plus depression care manager (nurse or psychologist) using stepped-care protocol, systematic outcome tracking, and consultation with psychiatrist; or (b) usual care from primary care physician
Assignment
Randomized controlled trial (patient-level, multi-site)
Sample size
1,801 adults aged 60+ with depression across 8 health care organizations
Primary outcome
Depression-free days over 24 months; depression remission rate; quality of life
Effect estimate
Depression-free days: +115 days over 24 months vs. usual care; clinical response at 12 months: 45% vs. 19%; quality-adjusted life year difference: 0.26 QALYs; cost-effective at $500 per QALY gained
Decision
IMPACT model replicated in 80+ studies and 5 countries; adopted by Kaiser Permanente, VA, and multiple state Medicaid programs; depression collaborative care became a reimbursable service under Medicare (2017) due partly to IMPACT evidence
Result
Positive
Depression-free days: +115 days over 24 months vs. usual care; clinical response at 12 months: 45% vs. 19%; quality-adjusted life year difference: 0.26 QALYs; cost-effective at $500 per QALY gained
Evidence strength
Strong
Randomized trial, replicated across multiple sites or studies.
Replication status
Replicated
Institution
University of Washington / RAND / multiple health systems
Location
United States
Year
2002
Policy area
Public Health
Mechanism
Human capital