Extent of Health Care Fragmentation in Different Payer Populations: Evidence from the Hudson Valley of New York.

Health care fragmentation occurs when patients see multiple ambulatory providers, but no single provider accounts for a substantial proportion of visits. Most previous studies have measured fragmentation in Medicare, which may not be generalizable. The study objective was to compare the extent of fragmented ambulatory care across commercially insured, Medicare, and Medicaid populations. The authors conducted a cross-sectional study of adults (N = 256,047) in the Hudson Valley region of New York, who were continuously insured (through 5 commercial payers, Medicare, or Medicaid), were attributed to a primary care physician, and had ≥4 ambulatory visits in the study year. Fragmentation was calculated using a reversed Bice-Boxerman Index, which captures both dispersion of care across providers and the relative share of visits by each provider. Chi-square tests, t tests, and correlation were used to compare patient characteristics and patterns of care across payers. Patients with Medicare had more chronic conditions (45% had ≥5 chronic conditions) than patients with commercial insurance (20%) or Medicaid (23%) (P < 0.01). However, mean fragmentation scores were comparable across all 3 payer populations: 0.73 (commercial insurance), 0.74 (Medicare), 0.72 (Medicaid). The correlation between number of chronic conditions and fragmentation was weak across payers, ranging from r = 0.004 to r = 0.12. If the extent of fragmentation does not vary with payer type or with the number of chronic conditions, it suggests that the causes of fragmentation may be more numerous and more complex than medical need alone.