Dosage and outcomes in a complex care intervention.

Objectives: The purpose of our study was to assess the relationship between intervention dosage and hospital utilization outcomes among patients with complex health and social needs enrolled in a care management program. We highlight the importance of measuring patient engagement and intervention dosage in program evaluation.

Study Design: We performed a secondary analysis of data collected between 2014 and 2018 as part of a randomized controlled trial of the Camden Coalition's signature care management intervention. Our analytical sample consisted of 393 patients.

Methods: We calculated a time-invariant cumulative dosage rank based on the number of hours spent by care teams working with or on behalf of patients and then divided patients into low- and high-dosage groups. We applied propensity score reweighting to compare hospital utilization outcomes between patients in these 2 groups.

Results: Compared with patients in the low-dosage group, those in the high-dosage group had a lower readmission rate at 30 (21.6% vs 36.6%; P < .001) and 90 (41.7% vs 55.2%; P = .003) days post enrollment. The difference between the 2 groups at 180 days post enrollment was not statistically significant (57.5% vs 64.9%; P = .150).

Conclusions: Our study elucidates a gap in how care management programs for patients with complex health and social needs are evaluated. Although the study shows an association between intervention dosage and care management outcomes, patients' medical complexity and social circumstances are among the factors that can attenuate the dose-response relationship over time.