Changes in Quality of Health Care Delivery after Vertical Integration.

Objectives: To fill an empirical gap in the literature by examining changes in quality of care measures occurring when multispecialty clinic systems were acquired by hospital-owned, vertically integrated health care delivery systems in the Twin Cities area.

Data Sources/study Setting: Administrative data for health plan enrollees attributed to treatment and control clinic systems, merged with U.S. Census data.

Study Design: We compared changes in quality measures for health plan enrollees in the acquired clinics to enrollees in nine control groups using a differences-in-differences model. Our dataset spans 2 years prior to and 4 years after the acquisitions. We estimated probit models with errors clustered within enrollees.

Data Collection/extraction Methods: Data were assembled by the health plan's informatics team.

Principal Findings: Vertical integration is associated with increased rates of colorectal and cervical cancer screening and more appropriate emergency department use. The probability of ambulatory care-sensitive admissions increased when the acquisition caused disruption in admitting patterns.

Conclusions: Moving a clinic system into a vertically integrated delivery system resulted in limited increases in quality of care indicators. Caution is warranted when the acquisition causes disruption in referral patterns.