the National Hospital Ambulatory Emergency Department Visit Rates by Selected Characteristics: United States, 2018

In 2018, there were an estimated 130 million emergency department (ED) visits in the United States (1). In 2019, approximately 22% of adults aged 18 and over had visited the ED in the past 12 months (2). This report presents ED visit rates by selected characteristics, including metropolitan statistical area (MSA), age, sex, race and ethnicity, and health insurance status. Data for this report are from the National Hospital Ambulatory Medical Care Survey (NHAMCS) (3,4).

• The ED visit rate was highest for infants under age 1 year (101 visits per 100 infants) followed by adults aged 75 and over (52 per 100 persons).
• The ED visit rate for females was higher than the rate for males.
• The ED visit rate for non-Hispanic black or African American persons (87 visits per 100 persons) was higher than the rate for persons from all other race and ethnic groups.
• The ED visit rate for patients with private insurance was lowest, while the rate for patients with Medicaid was highest compared with all other sources of payment.
In 2018, there were an estimated 130 million emergency department (ED) visits in the United States (1). In 2019, approximately 22% of adults aged 18 and over had visited the ED in the past 12 months (2). This report presents ED visit rates by selected characteristics, including metropolitan statistical area (MSA), age, sex, race and ethnicity, and health insurance status. Data for this report are from the National Hospital Ambulatory Medical Care Survey (NHAMCS) (3,4).
What were the ED visit rates overall and by MSA status, and did this vary during 2007-2018? • The overall ED visit rate remained stable at 39 visits per 100 persons in 2007 to 40 visits per 100 persons in 2018 ( Figure 1). What were the ED visit rates for each age group, and did these rates vary?
• In 2018, the ED visit rate for infants under age 1 year was 101 visits per 100 infants, which was highest compared with all other age groups ( Figure 2).
• The ED visit rate for adults aged 75 and over was 52 visits per 100 persons, which was higher than the rates for all other age groups, except infants under age 1 year.
• ED visit rates were similar for all other age groups, ranging from 35 to 41 visits per 100 persons. What were the ED visit rates by sex and race and ethnicity, and did these rates vary?
• The ED visit rate for females was 44 visits per 100 persons, which was higher than the rate for males (37 visits per 100 persons) ( Figure 3).
• In 2018, the ED visit rate for non-Hispanic black or African American persons was 87 visits per 100 persons, which was higher than the rates for persons from all other race and ethnic groups.
• The ED visit rate for non-Hispanic persons from race groups other than white or black or African American was 18 visits per 100 persons, which was lower than the rate for persons from all other race and ethnic groups.  What were the ED visit rates for each primary expected source of payment, and did these rates vary?
• The ED visit rate was highest for patients with Medicaid (97 visits per 100 persons) (Figure 4).
• The ED visit rate was lowest for patients with private insurance (23 visits per 100 persons).
• A difference between the ED visit rate for patients with Medicare (45 visits per 100 persons) was observed compared with visits among uninsured patients (37 visits per 100 persons), and patients with other primary expected source of payment (39 visits per 100 persons) but these differences were not significant.

Summary
This report examines 2018 ED visit rates by selected characteristics and presents trends from 2007 to 2018. The overall ED visit rate and visit rates by MSA status did not change significantly between 2007-2018. The ED visit rates for infants under age 1 year was higher than the rates for all other age groups, and the rate for adults aged 75 and over was higher than the rates for all other age groups, except infants. The ED visit rate for females was higher than the rate for males. The ED visit rate for non-Hispanic black or African American persons was higher than the rates for persons from all other race and ethnic groups, and the rate for non-Hispanic persons from race groups other than white or black or African American was lower than the rate for persons from all other race and ethnic groups. The ED visit rate for patients with Medicaid was higher than the rates for all other sources of payment, and the rate for private insurance was lower than the rates for all other sources of payment. This report shows the wide variation in ED visit rates by selected characteristics. Primary expected source of payment: During data collection, all sources of payment were collected. For patients with more than one source of payment, the hierarchy below was used (with Medicare counted first and self-pay and no charge counted last) to collapse payments into one mutually exclusive variable (primary expected source of payment). ■ 6 ■ • Self-pay or no charge: Self-pay are charges that are paid by the patient or patient's family, which will not be reimbursed by a third party. Self-pay includes visits for which the patient is expected to be ultimately responsible for most of the bill, even if the patient never actually pays it. This does not include copayments or deductibles. No charge or charity are visits for which no fee is charged (e.g., charity, special research, or teaching).

Definitions
• Other: Includes Workers' Compensation and other sources of payment not covered by the above categories, such as TRICARE, state and local governments, private charitable organizations, and other liability insurance (e.g., automobile collision policy coverage).

Data source and methods
Data for this report are from NHAMCS, an annual nationally representative survey of nonfederal, general, and short-stay hospitals (3,4). NHAMCS provides data on the utilization and provision of ambulatory care services in hospital EDs. In 2018, the weighted NHAMCS response rate was 88.5%. Data analyses were performed using the statistical packages SAS version 9.4 (SAS Institute, Cary, N.C.), SAS-callable SUDAAN version 11.0 (RTI International, Research Triangle Park, N.C.), and Joinpoint Regression Program version 4.7.0.0. Two-tailed t tests were used to determine significant differences between ED visit rates. The significance level for statistical testing was set at p < 0.05.