Ambulatory Care Monthly News

Stats of the Month

In recognition of National Influenza Vaccination Week (December 4-8), we present estimates for visits to emergency departments (ED) at which an influenza test was provided, from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, an influenza test was provided at 5.2% of all ED visits. Children younger than 18 were tested for influenza more frequently than adults. Children were tested at 10.2% of ED visits made by children whereas adults aged 18 and over were tested for influenza at 3.9% of ED visits made by adults. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

It is possible to combine two or more years of NHAMCS to increase the sample size. This allows you to produce estimates with greater statistical reliability for subgroup analyses (for example, age, sex, race, and Hispanic origin).

When combining years of data, it is important to:

1. Verify that the data items of interest are comparable in terms of how they were collected in each year.
2. Verify that the variable names have not changed over the years.
3. To obtain an annual average number of weighted visits using a combined file, divide the weighting variable PATWT by the number of years you are combining.  For example, if you are combining data for 2020 and 2021, you can create a new variable called PATWT2, defined as PATWT divided by 2 (PATWT/2). Weighting the data with PATWT2 will yield the annual average estimate for 2020 and 2021. If you run data for combined years and use the original weight (PATWT), your result will reflect a 2-year visit total rather than an annual average.

New Products This Month

Upcoming release:

Emergency Department Visit Rates by Adults with Diabetes: United States, 2020–2021
Data Brief (December 19, 2023)
KEY TOPICS: Emergency Department Visits, Diabetes

Visit this page to get updates on new products and releases.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of National Diabetes Month we present estimates for visits to emergency departments (ED) related to diabetes from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, there were approximately 19 million visits to the ED made by adults with diabetes in their medical record, representing 17.1% of all visits to the ED made by adults. Visits related to diabetes increased with age, with a higher percentage of visits made by adults ages 65 and over (31.6%) than by adults ages 44-64 (23.2%) and adults ages 18-44 (5.9%).  (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

When analyzing NAMCS and NHAMCS data with R software, use either the R “survey table” package (https://cdcgov.github.io/surveytable/ ) or the R “survey” package.  In “survey table”, use the “tab” function to generate tables with estimates of counts and percentages. In “survey”, use the “svytotal” function to generate estimates of counts and “svymean” to generate estimates of percentages.

New Products This Month

• Santo L, Peters ZJ, Davis D, DeFrances CJ. Emergency department visits related to mental health disorders among children and adolescents: United States, 2018–2021. National Health Statistics Reports; no 191. Hyattsville MD: National Center for Health Statistics. 2023. This report describes ED visits related to mental health disorders among children and adolescents and compares them with visits by children and adolescents without mental health disorders. Visit rates related to mental health disorders were higher among adolescents ages 12–17 compared with children younger than 12 years, among girls compared with boys, and among Black non-Hispanic compared with Hispanic children and adolescents. At approximately one-quarter of the ED visits by children and adolescents with any diagnosis of a mental health disorder, at least one psychiatric medication was received.
• 2022 NAMCS Health Center Component data are available in the NCHS Research Data Center. The data dictionary is available upon request. Email rdca@cdc.gov with the subject “2022 NAMCS Health Center Component Data Dictionary Request”.
• FROM LAST MONTH: QuickStats: Rate of Emergency Department Visits for Substance Use Disorders Among Adults Aged ≥18 Years, by Age Group — National Hospital Ambulatory Medical Care Survey, United States, 2018–2019 and 2020–2021. MMWR Morb Mortal Wkly Rep 2023;72:1073. This quickstats shows that, in 2020-2021, the rate of ED visits with a primary diagnosis of a substance use disorder among adults increased 42% among patients aged 18–34 years and 38% among patients aged ≥35 years since 2018–2019.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of Healthy Lung Month we present estimates for visits to emergency departments (ED) related to respiratory disorders from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, there were approximately 13.2 million visits to the ED made by patients with asthma in their medical record, representing 9.5% of all visits to the ED, and 8.1 million visits by patients with chronic obstructive pulmonary disease in their medical record, representing 5.8% of all visits to the ED (Estimates from the Public Use File and the 2021 Emergency Department Summary Tables)

Data Tip of the Month

Did you know . . .

README files containing instructions to create SAS, SPSS, and Stata datasets using the 2021 NHAMCS public use file are available here:

• SAS instructions
• SPSS instructions
• Stata instructions

Instructions for previous years for SAS, SPSS, and Stata are also available, along with pre-made SAS, SPSS, and Stata datasets for 2015-2021.

NHAMCS public use file documentation is available here, and public use data files in ASCII format are available here.

New Products This Month

• Davis D, Santo L. Emergency department visit rates for assault: United States, 2019–2021. NCHS Data Brief, no 481. Hyattsville, MD: National Center for Health Statistics. 2023. This report presents assault-related ED visit rates by selected demographic and hospital characteristics by using data from the 2019-2021 NHAMCS. During 2019–2021, there were 4.5 visits per 1,000 people per year to the ED related to assault. Visit rate for assault was highest for Black non-Hispanic people compared with all other race and ethnicity groups and among people with Medicaid as the primary expected source of payment. The ED visit rate for assault was higher for people who visited hospitals in metropolitan statistical areas compared with nonmetropolitan statistical areas.
• QuickStats: Rate of Emergency Department Visits by Homeless Status — National Hospital Ambulatory Medical Care Survey, United States, 2010–2021. MMWR Morb Mortal Wkly Rep 2023;72:42. This QuickStats shows that, during 2010–2021, the rate of ED visits by people experiencing homelessness increased from 141 visits per 100 people per year in 2010–2011 to 310 visits per 100 people in 2020–2021. During the same time period, the visit rates for people not experiencing homelessness remained constant, ranging from 42 visits per 100 people per year in 2010–2011 to 40 visits in 2020–2021.
• 2021 NHAMCS Emergency Department Summary Tables. Table 1 of this document was revised on October 11, 2023, to correct visit estimates for nursing home and homeless patients and update footnotes 2 and 3. (10/13/2023)

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of Healthy Aging Month we present estimates for visits to emergency departments (ED) by older adults from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, there were approximately 6.8 million visits related to injury made to the ED by adults ages 65 and over representing 18.5% of all injury visits and 4.9% of all ED visits.  Visits related to injury increased with age among older adults, with a higher percentage of visits made by adults ages 75 and over (10.3% of all injury visits) than by adults ages 65-74 (8.2% of all injury visits).  (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

The default confidence interval (CI) method commonly produced by statistical software is the Wald confidence interval [p ± 1.96 × SE(p) for a two-sided 95% CI]. The Wald CI is known to have limitations for proportions. The NCHS publication Data Presentation Standards for Proportions includes criteria based on the absolute width and the relative width of the Clopper-Pearson confidence interval, which was adapted for complex sample surveys by Korn and Graubard. The calculation of the Korn and Graubard CI incorporates information from the survey design, including the effective sample size and, when appropriate, the degrees of freedom.  For proportions estimated for a subgroup, the degrees of freedom should be calculated as (the number of PSUs with sampled observations in the subgroup of interest) – (the number of strata with sampled observations in the subgroup of interest). PSU is primary sampling unit.

New Products This Month

No new products this month.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of Children’s Eye Health and Safety Month we present estimates for visits to emergency departments (ED) for injury of the eye from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, there were approximately 8.7 million injury visits to the ED made by children and adolescents younger than 18 years. Among these visits, 1.4% were made for injury of the eye or orbit. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

Throughout the years, NAMCS and NHAMCS datasets and related documentation have been released in a variety of formats. When looking for a dataset to download or other survey information, the following pages could be useful:

The Datasets and Documentation page lists all the data files and documentation from the earliest to the newest releases. It also includes links for a Data Notices page as well as pages containing updates to the data files and documentation, if any.

The Survey Instruments page contains links to the NAMCS and NHAMCS Patient Record forms (called sample cards in recent years) and Induction Interview forms for physicians, community health center administrators and providers, and hospitals and emergency departments.

The Survey Methods and Analytic Guidelines page contains detailed information on survey methods, nonresponse bias, and the various classification systems used to code NAMCS and NHAMCS data.

New Products This Month

• QuickStats: Percentage of Emergency Department Visits with Medicaid as the Primary Expected Source of Payment Among Persons Aged <65 Years, by Race and Ethnicity — National Hospital Ambulatory Medical Care Survey, United States, 2011–2021. MMWR Morb Mortal Wkly Rep 2023;72:853. This QuickStats shows that, during 2011–2021, the percentage of ED visits among persons aged <65 years with Medicaid as the primary expected source of payment increased among all race and ethnicity groups. The percentages of ED visits among Black or African American and Latino or Hispanic persons with Medicaid as the primary expected source of payment were higher than the percentages of visits by White persons.
• 2021 NHAMCS EMERGENCY DEPARTMENT SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch released the most current nationally representative data on ambulatory care visits to hospital emergency departments in the United States. Estimates are presented on selected hospital, patient, and visit characteristics using data collected in the 2021 NHAMCS.

• Schappert SM, Santo L, Ward BW, Ashman JJ, DeFrances CJ. NHAMCS has been a trusted source of data for healthcare disparities research since 1992. Public Health Nurs. 2023 Jul 26. DOI: 10.1111/phn.13231. Epub ahead of print. PMID: 37495542. This letter to the editor describes how NHAMCS has been a trusted nationally representative data source for healthcare disparities research for more than 30 years. NHAMCS data can be used to perform time series analyses and allow for the study of ED visits among various geographic levels, patient age groups, and racial and ethnic groups. While NHAMCS may not be perfect for every research study, it has a long history of use to study a variety of healthcare topics.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of National Minority Mental Health Awareness Month (July), we present estimates for visits to emergency departments (ED) related to mental health from the 2021 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2021, approximately 13.4 million visits were made to the ED by patients with a diagnosis of a mental health disorder, accounting for 9.6% of all ED visits or 41.1 visits per 1,000 people. The rates of visits related to mental health disorders were higher among non-Hispanic black people (76.2 visits per 1,000 people) compared with non-Hispanic white people (40.8 visits per 1,000 people), Hispanic people (31.1 visits per 1,000 people) and non-Hispanic people of other races (16.8 visits per 1,000 people). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

You can view counts and rates of emergency department visits from 2016-2021 for the 10 leading primary diagnoses and reasons for visit, by patient and hospital characteristics of your interest. Estimates in this visualization highlight and expand on information provided in the annual NHAMCS web tables, which can be used to assess how these categories and rankings changed over the evaluated years. The tabs at the bottom of the visualization allow you to select between “Primary Diagnosis” and “Reason for Visit,” and the drop-down menus at the top of the visualization allow you to select the estimate type, the estimate category, and the group breakdown of interest.

New Products This Month

The 2021 NHAMCS Emergency Department public use data file and documentation are now available for downloading, along with SAS, Stata, and SPSS files for reading and formatting the data.  In addition to the SAS, Stata, and SPSS code which can be used with the ASCII data file to create data sets, we also provide pre-made SAS, Stata, and SPSS datasets. A drug ingredient file and program to add drug ingredients to the ASCII file is also available.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of Alzheimer’s and Brain Awareness Month, we present estimates for visits to emergency departments (ED) made by adults with Alzheimer’s disease in their medical record from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, approximately 2 million visits were made to the ED by adults with Alzheimer’s disease in their medical record, accounting for 1.9% of all ED visits made by adults. Visits by adults with Alzheimer’s disease increased by age. Among visits by adults aged 18-74, 0.7% had Alzheimer’s disease whereas among visits by adults aged 75 and over 9.9% had Alzheimer’s disease in their medical record. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .
To analyze NAMCS or NHAMCS public use files using SAS, two options are available.  Researchers can download a pre-made SAS dataset along with the corresponding SAS format file to run the data.  Option 2 is to download the public use file in ASCII format along with SAS input, label, and format statements.  These can be used to create one’s own SAS dataset.  An example of Option 1 using 2020 NHAMCS ED data is shown below:

Option 1:
Download the 2020 ED pre-made SAS dataset (ed2020_sas.zip) and format file (ed20for,txt) and save them to a folder of your choosing.

Right-click on the name of the zipped file from your directory screen. There should be an option to extract the file to a location of your choosing.

Use this SAS code to create a temporary working file. In this example, the data are saved to a folder called “c:myfilesnhamcs”
%INC “c:myfilesnhamcsed20for.txt”;  /*reads in the SAS formats from your downloaded format file*/
LIBNAME out1 “c:myfilesnhamcs”;  /*points to the location of the downloaded data file*/
DATA test20; set out1.ed2020_sas;  /*creates a temporary working file copied from the unzipped file*/
PROC SURVEYFREQ DATA=test20;
TABLES sex*ager /clwt cl;
CLUSTER cpsum;
STRATA cstratm;
WEIGHT patwt;
RUN;

For instructions on how to use the ASCII file to create your own SAS dataset (Option 2), see readme2020-ed-sas-txt.

New Products This Month

Cairns C, Ashman JJ, Peters ZJ. Emergency department visits among children aged 0–17 by selected characteristics: United States, 2019–2020. NCHS Data Brief, no 469. Hyattsville, MD: National Center for Health Statistics. 2023.

This data brief highlights changes in ED visits made by children aged 0–17, before and during the first year of the COVID-19 pandemic, a period with limited access to care. The report shows that the ED visit rate among children aged 0–17 decreased from 48 visits per 100 children in 2019 to 31 visits per 100 children in 2020. The ED visit rates for both boys and girls were lower in 2020 than in 2019. ED visit rates were also lower for Black or African American non-Hispanic children, White non-Hispanic children, and children of other non-Hispanic races in 2020 than in 2019.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of Older Americans Month (May), we present estimates for visits to emergency departments (ED) by adults aged 75 and older from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 14 million visits made to the ED by adults aged 75 and over, accounting for 10.6% of all ED visits.  Over one third (34.4%) of the visits made by adults aged 75 and over resulted in hospital admission, similar to the percentage of ED visits made by adults aged 65-74 (31.0%) and higher than the percentage of ED visits made by adults aged 45-64 (17.3%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

For the NHAMCS ED public use file (PUF), only the first four digits of the diagnosis codes, based on the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), are included. There is an implied decimal between the 3rd and 4th digits, and inapplicable 4th digits are dash-filled. For example: F321 = F32.1 Major depressive disorder, single episode, moderate. Because only 4 digits are included, more detailed codes are not available on the PUF. For instance, suicidal ideations (R45.851) is not an available code on the PUF. Instead, R45.841 would appear as R45.8 on the PUF (Other symptoms and signs involving emotional state) which includes conditions in addition to suicidal ideations. NCHS reports may present estimates using codes that are not available on the PUF. If access to the full ICD-10-CM codes is needed, it can be requested through the NCHS Research Data Center.

New Products This Month

No new products this month

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of National Minority Health Month (April), we present estimates for visits to emergency departments (ED) by patient race and ethnicity from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, minority populations accounted for 41.7% of all ED visits. Hispanic or Latino people made approximately 20.7 million visits, accounting for 15.8% of all ED visits; 28.2 million visits were made by non-Hispanic Black people, accounting for 21.4% of all ED visits; and 5.9 million visits were made by non-Hispanic people of other races*, accounting for 4.5% of all ED visits. (Estimates from the Public Use File)

^{* Includes Asian, Native Hawaiian or Other Pacific Islander, American Indian or Alaska Native, and people with more than one race.}

Data Tip of the Month

Did you know . . .

The National Center for Health Statistics new data presentation standards for rates and counts have been released. The multistep NCHS data presentation standards for rates and counts are based on a minimum sample size and the relative width of a confidence interval (CI). Specific criteria for rates and counts, including the CI calculations used, differ between vital statistics and health surveys and may differ according to the source of the denominator. For specific components of NCHS data presentation standards for rates and counts visit Vital Health and Statistics Series 2 No. 200.

New Products This Month

• Strashny A, Beresovsky V, Schappert SM, Santo L. Survey weights in the 2018 National Ambulatory Medical Care Survey adjusted using iterative proportional fitting. National Center for Health Statistics. Vital Health Stat 2(202). 2023.
  This report describes the adjustment of survey weights for the 2018 National Ambulatory Medical Care Survey using iterative proportional fitting (IPF). Compared with the previous adjustment method, IPF-adjusted weights have a lower maximum value, lower range, lower skewness, and lower design effect suggesting that IPF-adjusted weights produce more efficient estimates. Weight adjustment using IPF produced overall estimates of office-based physicians and their visits, which were not significantly different from totals based on the previous method.
• Strashny A, Cairns C, Ashman JJ. Emergency department visits with suicidal ideation: United States, 2016–2020. NCHS Data Brief, no 463. Hyattsville, MD: National Center for Health Statistics. 2023.
  This data brief shows that during 2016–2020, there were, annually, 40 visits per 10,000 people made by patients with suicide ideation. The visit rate for suicidal ideation was higher among males than females and highest among non-Hispanic Black people. The ED visit rate for suicidal ideation was lowest among hospital located in the Northeast.
• Davis D, Cairns C. Emergency department visit rates for motor vehicle crashes by selected characteristics: United States, 2019–2020. NCHS Data Brief, no 466. Hyattsville, MD: National Center for Health Statistics. 2023.
  This data brief shows that in 2019–2020, the annual average ED visit rate for motor vehicle crash injuries was 11.6 visits per 1,000 people. The ED visit rate was highest among patients aged 15–24 years and then declined with age. The visit rate was higher among non-Hispanic Black people, among patients with Medicaid and no insurance as primary expected source of payment and among hospitals located in the South.
• Ashman JJ, Santo L, Okeyode T. Characteristics of office-based physician visits by age, 2019. National Health Statistics Reports; no 184. Hyattsville, MD: National Center for Health Statistics. 2023.
  This report describes characteristics of office-based physician visits by using data from the 2019 National Ambulatory Medical Care Survey. In 2019, an estimated 1.0 billion office-based physician visits occurred in the United States. The visit rate among females was higher than for males, and the rates for both infants and older adults were higher than the rates for those aged 1–64. Private insurance was the primary expected source of payment for most visits by children under age 18 and adults aged 18–64, while Medicare was the primary expected source of payment for most visits by adults aged 65 and over. Visits for either chronic or pre- or post-surgery care increased with age. Visits for either preventive care or a new problem decreased with age.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Important Announcement

The National Center for Health Statistics (NCHS) would like to announce that the National Hospital Ambulatory Medical Care Survey (NHAMCS) will cease after the collection and processing of the 2022 annual data file. For 30 years, hospital visit data on the utilization and provision of ambulatory care services in hospital emergency departments, outpatient departments, and ambulatory surgery centers were collected as part of NHAMCS through manual medical record abstraction. These data were used to make national estimates on ambulatory visits to U.S. hospitals and were released as an annual public use file (PUF).

An important factor in the sunsetting of NHAMCS is the large-scale use of electronic health records by hospitals and wide availability of electronic hospital encounter data. With hospitals and health care providers storing and sharing data electronically, there is the ability for public health organizations to leverage these electronic data to enhance the understanding of hospital care through the collection of larger amounts of data, as well as the ability to link these data to external sources. Although NHAMCS is ending data collection, emergency department (ED) data collection and estimates will continue to be available at NCHS through the National Hospital Care Survey (NHCS). From a nationally representative sample of hospitals, the NHCS collects data electronically through the integration of various electronic data sources from emergency departments and inpatient hospital settings. Its data can be linked to additional data sources to study hospital-related mortality and the care received at hospitals, including the role of social determinants of health.

Although NHAMCS is ending with the 2022 survey year, data users will still be able to access NHAMCS reports and public use data files from the NCHS website. The 2021 NHAMCS PUF is expected to be released in the summer of 2023. The 2022 NHAMCS PUF is expected to be released in the summer of 2024. In addition, information on the continued collection of hospital data at NCHS can be found on the NHCS website.

Stats of the Month

In recognition of National Kidney Month (March) we present estimates for visits to emergency departments (ED) for chronic kidney disease (CKD) from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, adult patients with CKD documented in the medical record accounted for 5.4% of all visits to the ED made by adults aged 18 and over. Visits made by adult patients with CKD in the medical record varied by sex and increased by age. More visits were made by men (6.5%) than women (4.5%) and more visits were made by adults aged 65 and over (14.3%) than younger adults aged 45-64 (5.2%) and 18-44 (0.8%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

NAMCS and NHAMCS collect data on up to 30 medications provided, prescribed, or continued at the sampled visit. Each drug is first coded “as written” using an internal NCHS classification (MED1-MED30). Each drug also has associated characteristics added: the generic-equivalent code from Multum (DRUGID1-DRUGID30), prescription status (PRESCR1-PRESCR30), controlled substance status (CONTSUB1-CONSTUB30), composition status (COMSTAT1-COMSTAT30), and up to 4 Multum therapeutic categories (RX1CAT1-RX30CAT1, RX1CAT2-RX30CAT2, RX1CAT3-RX30CAT3, RX1CAT4-RX30CAT4). For each therapeutic category, there are also Level 1, Level 2 and Level 3 variables that together show the complete nested structure of the therapeutic category. For example, the drug rosuvastatin has a Level 1 code of metabolic agents, a Level 2 code of antihyperlipidemic agents, and a Level 3 code of HMG-CoA reductase inhibitors (statins). This enables you to run drugs at either the first, second, or third level of the therapeutic classification. More information can be found in the annual public use file documentation or on the website.

New Products This Month

Peters ZJ, Santo L, Davis D, DeFrances CJ. Emergency department visits related to mental health disorders among adults, by race and Hispanic ethnicity: United States, 2018–2020. National Health Statistics Reports; no 181. Hyattsville, MD: National Center for Health Statistics. 2023. This report shows differences by patient race and Hispanic ethnicity in ED visit characteristics related to mental health disorders. Rates of mental health-related ED visits were highest among non-Hispanic Black adults (96.8 visits per 1,000 adults), followed by non-Hispanic White (53.4) and Hispanic (36.0) adults. Rates of ED visits for specific mental health disorders, including substance use disorders, anxiety disorders, and mood disorders, were also highest among non-Hispanic Black adults.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

Stats of the Month

In recognition of American Heart Month (February), we present estimates for visits to emergency departments (ED) for coronary artery disease, ischemic heart disease, or history of myocardial infarction (MI) from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, patients with coronary artery disease, ischemic heart disease, or history of MI documented in the medical record accounted for 8.3% of all visits to the ED made by adults. Visits by patients with coronary artery disease, ischemic heart disease, or history of MI increased by age, representing 0.9% of ED visits made by adults aged 18-44, 11.7% of ED visits made by adults aged 45-74 and 24.0% of ED visits made by adults aged 75 and over. (Estimates from the Public Use File)
• In 2020, chest pain and related symptoms was the primary reason for visit in 6.3% of all visits to the ED made by adults aged 18 and over. Visits with chest pain and related symptoms as the primary reason for visit were higher among adults aged 45-74 (7.8%) than among adults aged 18-44 (5.4%) and adults aged 75 and over (4.7%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

The process for requesting access to restricted-use data from a federal statistical agency, including the National Center for Health Statistics (NCHS), has recently changed. For the first time, a standard application process (SAP) will be used by all 16 agencies comprising the U.S. Federal Statistical System.

This change makes NCHS and other federal data more accessible and usable for evidence-building purposes. Now data users only need to follow one process and complete a single application to request access to data from multiple agencies. Application review criteria have also been standardized through SAP.

The SAP portal houses the following resources:

• Metadata catalog: Data users can search key words to determine if NCHS or other federal statistical agencies have data suited to their specific-use cases. NCHS has restricted-use data on a variety of public health topics, including vital statistics, health and nutrition, health status, access to care, and ambulatory care services.
• Standard application: Data users can complete one application to request access to NCHS or other federal data sets using the SAP portal. In doing so, they must demonstrate that any data they access will be used for statistical purposes only. Data users can also track the status of their application as it moves through the review process. If approved, NCHS will guide applicants through the data access process.

If you have questions about SAP for accessing NCHS restricted-use data contact rdca@cdc.gov.

New Products This Month

No new products this month.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.

In 2021…

• The Ambulatory and Hospital Care Statistics Branch released several publications using data from the National Ambulatory Medical Care Survey (NAMCS) and from the National Hospital Ambulatory Medical Care Survey (NHAMCS). The publications consisted of NCHS data briefs, NCHS reports, QuickStats, web tables and manuscripts that can be found here or by selecting the publication name below. In 2022, the 2020 NHAMCS Emergency Department public use data file and documentation, the 2019 NAMCS public use data file and documentation, and the 2015 NAMCS Community Health Center public use data file and documentation were made available for downloading, along with SAS, Stata, and SPSS files for reading and formatting the data. A visit-level file based on 2020 NAMCS Community Health Center data was made available for use in the NCHS Research Data Center (RDC). Restricted data files may be accessed through the Research Data Center. Provider-level files based on the 2021 NAMCS data were also made available for use in the NCHS RDC.
• Visit the 2021 National Electronic Health Records Survey (NEHRS) Questionnaires, Datasets, and Related Documentation page for to download public use file documentation, pre-made SAS and Stata datasets,  questionnaire, and data dictionary.
• For the first time, dashboards depicting both counts and rates of emergency department (ED) visits from 2016-2020 NHAMCS for the 10 leading primary diagnoses and reasons for visit, stratified by selected patient and hospital characteristics, were made available. Estimates provided in the visualization highlight and expand on information provided in the annual NHAMCS web tables, which can be used to assess how these categories and rankings changed over the evaluated years. In addition to the new NHAMCS ED dashboards, two updates were published to the NAMCS COVID-19 dashboards that describe physician experiences during the COVID-19 pandemic.  Specifically, these updates added estimates using data from periods 1 and 2 of the 2021 NAMCS followed by periods 3 and 4 of the 2021 NAMCS.

Publications from NHAMCS and NAMCS in 2021

NCHS reports, data briefs and quickstats

• Cairns C, Ashman JJ, King JM. Emergency department visit rates by selected characteristics: United States, 2020. NCHS Data Brief, no 452. Hyattsville, MD: National Center for Health Statistics. 2022. This data brief shows that an estimated 40 emergency department (ED) visits per 100 people occurred in 2020. Most visits were made by non-Hispanic Black people and by patients with Medicaid as the primary expected source of payment. The ED visit rate was highest for infants (aged <1 year), followed by adults aged 75 years and over. An estimated 6.7% of ED visits in 2020 had any mention of COVID-19.
• Santo L, Schappert SM, Ashman JJ. Characteristics of visits to health centers, 2020. NCHS Data Brief, no 438. Hyattsville, MD: National Center for Health Statistics. 2022. This data brief shows that an estimated 12.4 health center visits per 100 people occurred in 2020. Most visits were made by patients with Medicaid as the primary expected source of payment and they were for preventive care (33.4%), new problems (32.8%), or chronic problems (32.1%). Screenings, examinations, and health education or counseling were provided at 60.0% of health center visits.
• Peters ZJ, Cairns C, Davis D. Experiences related to the COVID-19 pandemic among U.S. physicians in office-based settings, 2020–2021. National Health Statistics Reports; no 175. Hyattsville, MD: National Center for Health Statistics. 2022. This report shows that between September 2020 and May 2021, 31.1% of office-based physicians in the US experienced shortages of personal protective equipment, and 38.4% of physicians had to turn away COVID-19 patients or refer them elsewhere for care. The use of telemedicine for patient care increased from 43.1% before the pandemic to 88.4% after the start of the pandemic.
• Cairns C, Ashman JJ, Kang K. Emergency department visit rates by selected characteristics: United States, 2019. NCHS Data Brief, no 434. Hyattsville, MD: National Center for Health Statistics. 2022. This data brief shows that in 2019, the emergency department (ED) visit rate was 47 visits per 100 people. The ED visit rate was highest for infants (aged <1 year) (123 visits per 100 infants) and higher for non-Hispanic Black people (87 visits per 100 people) than for people from all other racial and ethnic groups. The ED visit rate for patients with Medicaid was highest compared with all other expected sources of payment.
• Santo L, Ashman JJ, Xu J. Emergency department visits by adults with chronic conditions associated with severe COVID-19 illness: United States, 2017–2019. National Health Statistics Reports; no 174. Hyattsville, MD: National Center for Health Statistics. 2022. This report shows that during 2017–2019, adults with at least one chronic condition made up 59.5% of emergency department (ED) visits made by adults. Hypertension was the most frequently observed chronic condition (33.8% of ED visits by adults) and hypertension and diabetes was the most frequently observed dyad, or pair (33.2% of ED visits by adults with at least two chronic conditions).
• QuickStats: Distribution of Emergency Department Visits Made by Adults, by Age and Number of Chronic Conditions — United States, 2017–2019. MMWR Morb Mortal Wkly Rep 2022;71:33. This QuickStats shows that in 2017-2019, 38.5% of adult emergency department (ED) visits were made by patients with no chronic conditions, 22.9% of the ED visits were made by adults with one chronic condition, 15.3% by those with two, and 23.3% by those with three or more chronic conditions; these percentages varied by age.
• QuickStats: Rates of Emergency Department Visits Related to Mental Health Disorders Among Adults Aged ≥18 Years, by Disorder Category — National Hospital Ambulatory Medical Care Survey, United States, 2017–2019. MMWR Morb Mortal Wkly Rep 2022;71:186. This QuickStats shows that during 2017–2019, 52.9 emergency department visits per 1,000 persons were related to a diagnosed mental health disorder and approximately one half of mental health related visits had a diagnosis of a psychoactive substance use disorder.
• QuickStats: Percentage of Office-Based Physicians Who Had Telephone or Internet/Email Consults with Patients — National Ambulatory Medical Care Survey, United States, 2018 and 2020. MMWR Morb Mortal Wkly Rep 2022;71:505. This QuickStats shows that in 2020, 57.4% of office-based physicians reported having telephone consults with patients during their last normal week of practice, higher than the 35.8% in 2018. Also, the percentage who reported having internet/email consults with patients increased from 13.9% in 2018 to 26.8% in 2020.
• QuickStats: Emergency Department Visit Rates, by Age Group — United States, 2019–2020. MMWR Morb Mortal Wkly Rep 2022;71:1350. This QuickStats shows that the emergency department (ED) visit rates for infants, children and adolescents decreased from 2019 to 2020. Visit rates for infants (aged <1 year) declined from 123 visits per 100 infants during 2019 to 68 during 2020. The ED visit rate for children and adolescents aged 1–17 years also decreased from 43 to 29 visits per 100 persons.
• QuickStats*: Percentage of Office-Based Physicians Using Telemedicine Technology, by Specialty — United States, 2019 and 2021. MMWR Morb Mortal Wkly Rep 2022;71:1565. This QuickStats shows that, from 2019 to 2021, the use of telemedicine technology increased for office-based physicians from 15.4% to 85.9% . It also shows that the use of telemedicine was higher among primary care physicians and medical specialty physicians than it was among surgical specialty physicians.
• QuickStats*: Percentage of Emergency Department Visits for Pain at Which Opioids Were Given or Prescribed, by Patient Age and Year — National Hospital Ambulatory Medical Care Survey, United States, 2010–2020. MMWR Morb Mortal Wkly Rep 2022;71:1634. This QuickStats shows that during 2010–2020, the percentages of emergency department visits for pain at which an opioid was given or prescribed decreased for all age groups.

*These QuickStats did not appear in the December newsletter since they were published after the newsletter was released. 

Web tables

• 2020 NHAMCS EMERGENCY DEPARTMENT SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch released the most current nationally representative data on ambulatory care visits to hospital emergency departments in the United States. Estimates are presented on selected hospital, patient, and visit characteristics using data collected in the 2020 NHAMCS.
• 2020 NAMCS COMMUNITY HEALTH CENTER SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch released the most current nationally representative data on visits to community health centers (CHC) in the United States. Estimates are presented on selected patient and visit characteristics using data collected in the 2020 NAMCS CHC.

• 2019 NHAMCS EMERGENCY DEPARTMENT SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch released nationally representative data on ambulatory care visits to hospital emergency departments in the United States. Estimates are presented on selected hospital, patient, and visit characteristics using data collected in the 2019 NHAMCS.
• 2015 NAMCS COMMUNITY HEALTH CENTER SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch released nationally representative data on ambulatory care visits to community health centers (CHC) in the United States. Estimates are presented on selected provider, patient, and visit characteristics using data collected in the 2015 NAMCS CHC.

New Products This Month

• Santo L, Schappert SM. Opioids prescribed to adults at discharge from emergency departments: United States, 2017–2020. NCHS Data Brief, no 461. Hyattsville, MD: National Center for Health Statistics. 2022. This report shows in 2019–2020, the rate of emergency department (ED) visits with opioids prescribed at discharge decreased overall and among women and men compared with 2017–2018.  The percentage of ED visits with opioids prescribed at discharge decreased among all adults, among non-Hispanic White and non-Hispanic Black adults, and among visits according to all primary expected sources of payment.
• 2019 NATIONAL AMBULATORY MEDICAL CARE SURVEY SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch is pleased to release the most current nationally representative data on ambulatory care visits to physician offices in the United States. Estimates are presented on selected physician, patient, and visit characteristics using data collected in the 2019 NAMCS.

Data Tell Stories

Do you have a story to share? How have you used information from the National Ambulatory Medical Care Survey or the National Hospital Ambulatory Medical Care Survey? Email us a brief description at ambcare@cdc.gov. In the subject field of your email, write “My NAMCS/NHAMCS data use example”. Your examples will help us showcase the value of NAMCS and NHAMCS.