It's who you know: patient-sharing, quality, and costs of cancer survivorship care.

PURPOSE: Cancer survivors frequently receive care from a large number of physicians, creating challenges for coordination. We sought to explore whether cancer survivors whose providers have more patients in common (e.g., shared patients) tend to have higher quality and lower cost care.
METHODS: We performed a retrospective cohort study of 8,661 patients diagnosed with loco-regional breast, prostate, or colorectal cancer. We examined survivorship care from days 366 to 1,095 following their cancer diagnosis. Our primary independent variable was "care density," a novel metric of the extent to which a patient's providers share patients with one another. Our outcome measures were health care utilization, quality metrics, and costs.
RESULTS: In adjusted analyses, we found that patients with high care density--indicating high levels of patient-sharing among their providers--had significantly lower rates of hospitalization (OR 0.87, 95% CI 0.75-1.00) and higher odds of an eye examination for diabetes (OR 1.31, 95% CI 1.03-1.66) compared to patients with low care density. High care density was not associated with emergency department visits, avoidable outcomes, lipid profile following an angina diagnosis, or odds of glycosylated hemoglobin testing for diabetes. Patients with high care density had significantly lower total costs of care over 24 months (beta coefficient -$2,116, 95% CI -$3,107 to -$1,125) along with lower inpatient and outpatient costs.
CONCLUSION: Cancer survivors treated by physicians who share more patients with one another tend to have some higher aspects of quality and lower cost care. IMPLICATIONS OF CANCER SURVIVORS: If validated, care density may be a useful indicator for monitoring care coordination among cancer survivors and potentially targeting interventions that seek to improve care delivery.