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Higher primary care density is associated with fewer preventable hospital admissions

Certain hospital admissions are potentially preventable by appropriate outpatient care. These ambulatory-care-sensitive (ACS) admissions range from uncontrolled asthma, diabetes, and hypertension to bacterial pneumonia, severe urinary tract infections, and dehydration. Preventable hospitalizations are less likely in areas that have higher primary care density, according to a study by researchers at the Agency for Healthcare Research and Quality.

Jayasree Basu, Ph.D., Bernard Friedman, Ph.D., and Helen Burstin, M.D., examined the association between potentially preventable hospitalizations and other factors, including primary care availability and health maintenance organization (HMO) enrollment (which emphasizes primary care). To accomplish this, they analyzed 1995 hospital discharge files (AHRQ's Healthcare Cost and Utilization Project) of New York residents (aged 20 to 64 years) hospitalized in New York or in either of three nearby States.

The researchers compared ACS admissions with marker admissions (urgent, but non-ACS, such as hip fracture and heart attack) and referral-sensitive surgeries (usually based on physician discretion, such as hip joint replacement), using the individual discharge as the unit of analysis. Although 15.4 adult patients per 1,000 adults in the U.S. population were admitted with an ACS condition in 1995, only 2.6 adults per 1,000 were admitted for referral-sensitive conditions and only 2.2 per 1,000 for marker conditions.

One additional primary care physician per 1,000 population (a doubling of the average availability) in a county was associated with an 80 percent lower probability of an ACS admission relative to marker admissions. Surprisingly, a greater supply of primary care was also associated with fewer referrals to hospitals. A private HMO-covered patient (but not an HMO-covered Medicaid beneficiary) was less likely to be an ACS admission. All Medicaid patients were more likely than other patients to be admitted for ACS conditions and less likely to be admitted for referral-sensitive procedures. Density of specialists was not associated with ACS admissions.

See "Primary care, HMO enrollment, and hospitalizations for ambulatory care sensitive conditions: A new approach," by Drs. Basu, Friedman, and Burstin, in Medical Care 40(12), pp. 1260-1269, 2002.

Reprints (AHRQ Publication No. 03-R014) are available from the AHRQ Publications Clearinghouse.

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