Changes in health-care payments and demand for coordinated care have led to an increase in vertical relationships between physicians and health systems in recent years.

"There are both potential social benefits and adverse consequences to vertical consolidation," according to a study published in JAMA Health Forum. "Physician–health system relationships may facilitate enhanced care coordination and communication among physicians and hospitals, which could play a role in lower duplicative testing or avoidable emergency department visits and thereby increase quality of care and decrease spending. Conversely, disrupting referral patterns could be associated with interrupted patient-physician relationships and lower quality."

Researchers analyzed how vertical relationships between primary care physicians and large health systems, which include specialists and hospitals, are associated with changes in ambulatory and acute care utilization, referral patterns, readmissions and total medical spending for commercially insured individuals in Massachusetts.