IMPACT Collaborative Care for Late-Life Depression

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

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