In California, an increase in the penetration of managed care is associated with a reduction in hospital admission rates for outpatients with chronic health conditions, according to a UCSF study.

"These results are among the first to suggest that managed care is linked with an improvement in primary care effectiveness," said Lisa Backus, MD, PhD, UCSF assistant professor of medicine and lead author of the study. The study appears in the April issue of the journal Medical Care.

The researchers noted that the cause of decreased hospitalizations remains unclear and should be addressed in future research. Assuming that decreases in hospitalization rates reflect better disease management strategies (one of the hallmarks of managed care), then managed care may have improved integration of inpatient and outpatient care, said Andrew Bindman, MD, UCSF professor of medicine, epidemiology and biostatistics and senior investigator on the study.

"Reduced hospitalizations may result from the fact that care providers can monitor conditions like asthma, diabetes and hypertension more closely and prevent chronic conditions from getting serious enough to require hospitalization," he said. "On the other hand, it is possible that managed care has achieved these benefits by simply raising the threshold for hospital admission."

The researchers explained that hospitalization rates have become a standard benchmark by which researchers can analyze the effectiveness of primary care. Previous studies have shown that Medicaid patients who had more continuity of care with a regular provider had lower rates of hospitalization for chronic conditions.

In other studies, hospitalization rates for conditions that can be treated on an outpatient basis have also been shown to be higher in physician workforce shortage areas and in low-income communities that do not have federally qualified health centers or free clinics, they said. Federally qualified centers, funded specifically to help low-income populations, have lower rates of hospital admission for conditions that can be treated on an outpatient basis than do other Medicaid providers.

In an additional study that analyzed California trends, higher patient ratings of access to care were strongly associated with lower hospitalization rates for conditions such as asthma, diabetes and hypertension that can often be treated on an outpatient basis. This association was significant after adjusting for community difference in the prevalence of disease, patient demographics, insurance status, patient health-seeking behavior, and physician admitting practices.

In the new study, researchers analyzed 1990-1997 data on managed care penetration and hospitalization rates for adults (ages 18-64) in 394 communities throughout the state of California. In 1990, adult populations in these areas ranged from 1,721 to 598,800. Private managed care penetration in each area was determined annually from statewide hospital discharge data.

Additional researchers on the study include Marie Moron, MD, public health resident at the University of Toulouse, France; Peter Bacchetti, PhD, UCSF professor of epidemiology and biostatistics; and Laurence C. Baker, PhD, assistant professor of health research and policy at Stanford University. The study was funded in part by the United States Health Resources and Services Administration.