JAMA Intern Medicine: June 17, 2013
Importance The Medicare accountable care organization (ACO) programs rely on delivery system integration and health care provider risk sharing to lower spending while improving quality of care.
Objective To compare spending and quality between larger and smaller provider groups and examine how size-related differences vary by 2 factors considered central to ACO performance: group primary care orientation and financial risk sharing by health care providers.
Evidence Review Using 2009 Medicare claims and linked American Medical Association Group Practice data, we assigned 4.29 million beneficiaries to health care provider groups based on primary care use. We categorized group size according to eligibility thresholds for the Shared Savings (≥5000 assigned beneficiaries) and Pioneer (≥15 000) ACO programs and distinguished hospital-based from independent groups. We assessed the primary care orientation of larger groups’ specialty mix and used health maintenance organization market penetration and data from the Community Tracking Study to measure the extent of financial risk accepted by different types of provider groups in different areas for managed care patients. Read more