Rates of preventable hospital admissions appear lower in smaller primary care practices

Rates of preventable hospital admissions appeared to be lower in smaller primary care practices compared with larger ones, according to a recent study.

Researchers used survey data from the National Study of Small and Medium-Sized Physician Practices to examine whether ambulatory care-sensitive admission rates were associated with physician practice characteristics such as size and ownership, processes used to improve care, or external incentives to improve quality and cost control. A total of 1,745 practices (63.2%) responded to the survey. The current study involved data only from the 1,045 practices that were made up of at least 33% primary care physicians, were not community health centers, and saw patients in 2008. Medicare data from 2008 were used to determine practices' rates of ambulatory care-sensitive hospital admissions. Practices were divided into 3 different groups: 1 to 2 physicians (small), 3 to 9 physicians (medium), and 10 to 19 physicians (large). The study results were published early online and will appear in the September Health Affairs.

Most practices included in the study had 1 to 2 or 3 to 9 physicians (54.5% and 40.4%, respectively). Practices that included 10 to 19 physicians made up 5.1% of the sample. A total of 16.7% of practices were owned by hospitals. Compared with practices that had 3 to 9 physicians, those with 1 to 2 had significantly more patients who were covered by Medicaid and Medicare (i.e., dual-eligible), patients who were ethnic or racial minorities, and patients with multiple chronic conditions. Practices with 10 to 19 physicians used 24.1% of available patient-centered medical home processes compared with 25.6% in practices with 3 to 9 physicians and 19.1% in practices with 1 to 2 physicians.

Overall, the mean ambulatory care-sensitive admission rate was 4.6 per 100 beneficiaries annually. Rates in unadjusted bivariate analysis were 4.2, 5.1, and 6.1 per 100 patients annually for small, medium, and large practices, respectively. Ambulatory care-sensitive admission rates were significantly lower for physician-owned compared with hospital-owned practices (4.3 vs. 6.4 per 100 patients annually, respectively).

In adjusted analyses that looked at associations with the patient-centered medical home score, pay-for-performance incentives, acceptance of risk for hospital care costs, and public reporting, small practices had significantly lower ambulatory care-sensitive admission rates than large practices (4.31 vs. 6.47 per 100 patients annually, respectively) and physician-owned practices had significantly lower rates than hospital-owned practices (4.63 vs. 5.31 per 100 patients annually, respectively).

The authors noted that their study is observational, that their results may not represent all U.S. practices, that they did not include practices made up primarily of subspecialists or practices with more than 20 physicians, and that data on practice characteristics were self-reported, among other limitations. However, they concluded that small practices with 1 to 2 physicians and medium-sized practices with 3 to 9 physicians had 33% and 27% fewer preventable admissions than large practices with 10 to 19 physicians and that physician-owned practices had lower rates than hospital-owned practices.

The authors noted that they could not determine a causal relationship between practice size and ownership and preventable admission rates and noted that larger practices are usually better able to implement organized performance improvement processes. However, they speculated that smaller practices may be able to offer patients better service and that physicians, staff, and patients at smaller practices may know each other better; these advantages, the authors said, may help lead to lower rates of preventable admissions.

“Our results suggest that the common assumption that bigger is better should not be accepted without question, at least in practices of nineteen or fewer physicians,” the authors wrote. They suggested that independent practice organizations, for example, “might provide a viable alternative, in the era of health care reform, for physicians who do not want to become employed by hospitals and do not have the desire or the opportunity to join a large medical group.” They called for more research comparing the performance of different types of practices, since evidence on how physician practice structure affects practices and outcomes is scarce.