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8 Outpatient Clinic Statistics and Definitions Every Healthcare Operator Should Know in 2026

"Outpatient clinic" sounds like one industry, but the official data divide it across physician offices, outpatient care centers, health centers, hospital departments, and other ambulatory services. A market-size number is only useful when the reader knows exactly which of those settings it includes.

We read the original Census profile for Offices of Physicians, the CDC's National Ambulatory Medical Care Survey overview, the 2024 NAMCS documentation, the CDC's National Hospital Ambulatory Medical Care Survey overview, and the BLS profile for Ambulatory Health Care Services. We extracted the most useful figures and the limitations that determine whether each statistic can be used for establishments, providers, employees, or visits.

Back to Clinic statistics

1. Census counted 218,066 employer establishments in Offices of Physicians in 2023

The Census Bureau's 2023 County Business Patterns profile for NAICS 6211 reports 218,066 total employer establishments in the United States. NAICS 6211 covers establishments where health practitioners with an M.D. or D.O. primarily engage in the independent practice of general or specialized medicine or surgery. The Census examples include anesthesiology, oncology, ophthalmology, psychiatry, and surgery.

That 218,066 figure is an establishment count, not a count of outpatient clinics in every possible sense. It does not tell you the number of providers, visits, employees, revenue, or payroll, and it does not automatically include other health practitioners, outpatient care centers, hospital outpatient departments, laboratories, or home health services. It is a precise answer to a narrow question: how many employer establishments are in the Census offices-of-physicians industry.

Clinic type or source Statistical code What is counted Establishments or providers Visits Employees Revenue or payroll Year Exclusion or limitation Source
Offices of Physicians NAICS 6211 Independent practice of general or specialized medicine or surgery by M.D. or D.O. practitioners 218,066 employer establishments Not provided by the CBP profile Not provided by the CBP profile Not provided by the CBP profile 2023 Not the full outpatient clinic market Census profile
Ambulatory Health Care Services NAICS 621 Seven ambulatory industry groups 774,559 private establishments in Q4 2025, preliminary Not provided by the BLS profile 9,233,300 all employees in June 2026, preliminary Not provided by the BLS profile 2025 to 2026 Includes dentists, laboratories, home health, and other groups beyond clinics BLS profile
NAMCS Provider Survey Component Office-based provider survey, no NAICS code Office-based physicians and physician associates 2024 provider-level pilot data No visit-level data collected in 2024 Not an employee survey No revenue or payroll measure 2024 Unweighted, no national estimates; excludes radiologists, pathologists, and Indian Health Service Centers CDC 2024 documentation
NAMCS Health Center Component Health center survey component, no NAICS code Facility information and submitted health-center visit data Public-use file is a 5% sample of submitted health-center visit data Sampled health-center visits No employee count No revenue or payroll measure 2024 Not a 5% sample of every outpatient clinic visit in the United States CDC NAMCS overview and 2024 documentation
NHAMCS hospital ambulatory care Hospital survey, no current outpatient code Hospital emergency and outpatient department medical services Approximately 500 hospitals supplied sampled data in the final years Sample of patient visits from a reporting period No employee count No revenue or payroll measure Outpatient departments through 2017; survey ended 2022 No current national hospital outpatient department series after 2017 CDC NHAMCS overview

2. NAICS 621 contains seven industry groups, so ambulatory health care is broader than outpatient clinics

The BLS definition of Ambulatory Health Care Services covers services delivered to ambulatory patients, usually without inpatient care. Its NAICS 621 subsector includes Offices of Physicians (6211), Offices of Dentists (6212), Offices of Other Health Practitioners (6213), Outpatient Care Centers (6214), Medical and Diagnostic Laboratories (6215), Home Health Care Services (6216), and Other Ambulatory Health Care Services (6219).

This list is why two apparently authoritative market-size figures can both be correct and still be incomparable. A writer describing physician practices may need 6211. A writer describing urgent care or another outpatient center may need 6214. A figure for all of 621 also includes dentists, laboratories, home health, and other services that are not part of a clinic operator's target market.

3. BLS reported 9.233 million ambulatory employees in June 2026, but that is not clinic employment alone

The BLS profile reports 9,233.3 thousand seasonally adjusted employees in Ambulatory Health Care Services in June 2026. The same page reports 774,559 private-industry establishments in the fourth quarter of 2025, marked preliminary, and average hourly earnings of $41.12 for all employees in May 2026, also marked preliminary. These figures provide current workforce and operating context for the broad subsector.

They should not be presented as the workforce, establishment count, or average wage of outpatient clinics alone. The BLS series uses NAICS 621, while the Census figure above uses NAICS 6211 and a different program, year, and unit. The safest comparison is to label the BLS number as ambulatory health care context and keep it separate from a physician-office market estimate.

4. NAMCS covers office-based providers and health centers, not every outpatient setting

The CDC says NAMCS collects data about medical services provided in office-based health care settings and about patients who visit health centers. Its provider scope includes office-based physicians and other nonfederal healthcare professionals. Its health-center component includes centers serving areas and groups with limited access to medical care, including federally funded and nonfederally funded centers.

NAMCS is therefore useful for questions about patients, medical visits, conditions, diagnoses, and services in the settings it samples. It does not cover radiologists or pathologists, and it does not collect data from Indian Health Service Centers. It is a healthcare visit survey, not a universal directory of every establishment that someone might call an outpatient clinic.

5. The 2024 NAMCS provider component cannot support national provider or visit estimates

The CDC states that 2024 was a pilot year for the NAMCS Provider Survey Component. The data are unweighted and do not allow national estimates. No visit-level data were collected in 2024; the available data are provider-level files for office-based physicians and physician associates.

That limitation changes how the data can be used in an article. A researcher can explain what the pilot collected and use its documentation to understand the survey design, but should not turn a 2024 provider count or response pattern into a national estimate for outpatient clinics. The absence of a weighted national estimate is part of the result and should be stated next to any 2024 claim.

6. The 2024 NAMCS health-center public-use file is a 5% sample of submitted visit data

The 2024 Health Center Component is a separate part of NAMCS. Its public-use file is a 5% sample of submitted health-center visit data, rather than a count of every visit made to every outpatient clinic in the country. The file is valuable for working with health-center visit records, but its sampling frame and component definition must stay attached to the statistic.

The word "submitted" matters. A sample of submitted health-center data is not automatically the same as a sample of all healthcare encounters, all clinics, or all patients. When using a health-center figure, identify the component, file year, sample status, and whether the value is a raw sample count, a weighted estimate, or a published result based on the file.

7. NHAMCS hospital outpatient data are historical, not a current national benchmark

The CDC says the National Hospital Ambulatory Medical Care Survey ended data collection after 2022. More importantly for outpatient clinic research, NHAMCS stopped collecting data from hospital outpatient departments in 2018. During its last five years, from 2018 through 2022, the survey collected only emergency department data. In the final years of the survey, approximately 500 hospitals supplied data on sampled patient visits from a reporting period.

This makes NHAMCS a useful historical source for hospital-based ambulatory care, but not a current national benchmark for hospital outpatient departments. If an article quotes hospital outpatient visit statistics from NHAMCS, it should state the data year and the fact that the outpatient-department series ended in 2017. A current clinic comparison needs a newer source or a clearly labelled local or administrative dataset.

8. Use five definition checks before quoting any outpatient clinic statistic

Before using a number, write the answer to these five questions beside it:

If those answers are missing, the statistic is not ready to support a market-size claim. The strongest outpatient clinic articles do not force every source into one total. They show the reader which slice of care each number describes, then explain where the slices cannot be added together.

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