Context: The US primary care safety net is composed of a loose network of community health centers, hospital outpatient departments, and physicians' offices. National data on how the mix of patients and services differ across sites are needed.
Objective: To develop and contrast national profiles of patient and service mix for primary care.
Design, setting, and patients: Comparative analyses of 3 national surveys of primary care visits occurring in 1994: for data on physician's office visits, the National Ambulatory Medical Care Survey (NAMCS); for hospital outpatient department data, the National Hospital Ambulatory Medical Care Survey (NHAMCS); and for data on community health centers, the Bureau of Primary Health Care's 1994 Survey of Visits to Community Health Centers. A time trend analysis also was conducted using the 1998 NAMCS and NHAMCS.
Main outcome measures: National estimates of primary care visit rates, types of patient presentation, patient case-mix, disposition of patients, and management interventions in 1994, and compared with 1998 data.
Results: The US population made 1.3 primary care visits per person in 1994, which accounted for 43.5% of all ambulatory visits to physicians' offices, community health centers, and hospital outpatient departments. Primary care visits per person were 20% lower for Hispanics and 33% lower for black, non-Hispanic persons compared with white, non-Hispanic persons. Visits to community health centers were more likely to be made by ethnic minorities, patients with Medicaid or no insurance, and rural dwellers than visits made to the other delivery sites. Visits at hospital outpatient departments were made by sicker populations and were characterized by less continuity than the other delivery sites. Controlling for patient mix, visits made to hospital outpatient departments were more commonly associated with imaging studies, minor surgery, and specialty referrals than those made to physicians' offices. In 1998, the US population made an estimated 3. 4 visits per person, 45.6% of which were primary care visits. National estimates of primary care visit rates and patient mix and practice pattern comparisons between hospital outpatient departments and physicians' offices were similar in 1998 and 1994.
Conclusions: Expanding community health centers will likely improve access to primary care for vulnerable US populations. However, enhancing access to of physicians' offices is also needed to bolster the safety net. The greater service intensity and poorer continuity for primary care visits in hospital outpatient departments that we observed raises concern about the suitability of these clinics as primary care delivery sites. JAMA. 2000;284:2077-2083.