National Hospital Ambulatory Medical Care Survey: 1999 emergency department summary.

OBJECTIVES: This report describes ambulatory care visits to hospital emergency departments (ED's) in the United States. Statistics are presented on selected hospital, patient, and visit characteristics. Highlights of trends in ED utilization from 1992 through 1999 are also presented.

METHODS: The data presented in this report were collected from the 1999 National Hospital Ambulatory Medical Care Survey (NHAMCS). NHAMCS is part of the ambulatory care component of the National Health Care Survey that measures health care utilization across various types of providers. NHAMCS is a national probability survey of visits to hospital emergency and outpatient departments of non-Federal, short-stay, and general hospitals in the United States. Sample data are weighted to produce annual national estimates. Trends are based on NHAMCS data for 1992, 1993-94, 1995-96, 1997-98, and 1999.

RESULTS: During 1999, an estimated 102.8 million visits were made to hospital ED's in the United States, about 37.8 visits per 100 persons. The volume of ED visits increased by 14 percent from 1992 through 1999, though no trend was observed in the overall population-based visit rates. There was a significant increase in the visit rate for black persons 75 years of age and over. In 1999, persons 75 years of age and over had the highest ED visit rate and 41.5 percent of these patients arrived by ambulance. There were an estimated 37.6 million injury-related ED visits during 1999, or 13.8 visits per 100 persons. Seventy-four percent of injury-related ED visits were made by persons under 45 years of age. Injury visit rates were higher for males than females in each age group under 45 years. The case mix of visits at ED's changed since 1992, with a greater percent of visits presenting with illness rather than injury conditions. Abdominal pain, chest pain, fever, and headache were the leading patient complaints accounting for one-fifth of all visits. Acute upper respiratory infection was the leading illness-related diagnosis at ED visits. Increases were observed in visits where no complete diagnosis could be made (16.2 percent of visits in 1999). Diagnostic and/or screening services were provided at 89.0 percent of visits, procedures were performed at 42.5 percent of visits, and medications were provided at 72.5 percent of visits. Pain relief drugs accounted for 31.1 percent of the medications mentioned. Trend data from 1992 indicated that the use of medications at ED visits increased. In 1999, approximately 13 percent of ED visits ended in hospital admission. Facility-level data indicated that there is variation among hospital ED's with respect to case mix, number of services provided, and case disposition distributions, especially the percent admitted to the hospital.