Ambulatory Care Monthly News

Stats of the Month

In recognition of National Influenza Vaccination Week (December 5-9), we present estimates for visits to emergency departments (ED) by patients with influenza and pneumonia, from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 5.5 million visits made to the ED by patients with a diagnosis of influenza and pneumonia*, representing 4.2% of all ED visits. More of these visits were made by adults aged 65 and over (8% of the ED visits by patients aged 65 and over) than by patients younger than 65 (3.2% of the ED visits by patients younger than 65). (Estimates from the Public Use File)

*Diagnoses were coded according to the International Classification of Diseases, 10th Revision, Clinical Modification (ICD–10–CM) coding system (ICD–10–CM, J09–J18).

Data Tip of the Month

Did you know . . .

When analyzing NAMCS and NHAMCS data with R software, the R “survey” package should be used. The svydesign function combines a data frame and all the survey design information needed to analyze it. It is important to never subset the data frame before using the svydesign function. If you subset your data frame before defining your survey design object, you may produce incorrect variance estimates.

New Products This Month

Expected later this month: 2020 NHAMCS ED web tables and 2020 NAMCS ED dashboard.  Please check the NHAMCS What’s New page in a few weeks.

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 Chronic Obstructive Pulmonary Disease (COPD) Awareness Month we present estimates for visits to emergency departments (ED) by adults with COPD from the 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 8.2 million visits to the ED made by adults aged 18 years and over with COPD in the medical record, representing 7.5% of all ED visits made by adults. Visits by adults with COPD were higher among older adults; 15.4% of visits made by adults aged 65 years and over had COPD in the medical record, higher than visits by adults aged 18-64 years (4.9%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

When combining multiple years of NAMCS or NHAMCS data always check the contents of the data files because variable names may be different from year to year.  You can download the documentation for the years of interest here. The codebook section lists all the variables in the data file. If the labels of the variables of interest have changed, you should recode the variables to make their names and response categories consistent before appending the data.

New Products This Month

• QuickStats: Emergency Department Visit Rates, by Age Group — United States, 2019–2020. MMWR Morb Mortal Wkly Rep 2022;71:1350. This QuickStat shows that 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 in 2019 to 68 visits per 100 infants in 2020. The visit rate for children and adolescents aged 1–17 years decreased from 43 visits per 100 children and adolescents in 2019 to 29 visits per 100 children and adolescents in 2020.
• 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.
• The 2019 NAMCS 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 for adding drug ingredients is also available.
• An addendum to the 2018 NAMCS public use data file documentation is now available, along with a SAS data set containing a refined version of the patient visit weight and the physician weight. The addendum includes a program to merge the new variables to the existing 2018 NAMCS public use data file. The refined weighting variables reflect changes made to the weighting methodology used with the 2019 NAMCS. They are being provided should researchers wish to use the same methodology for both survey years. See the addendum for more information.

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 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 12.7 million visits to the ED made by patients with asthma in their medical record, representing 9.7% of all visits to the ED, and 8.2 million visits by patients with chronic obstructive pulmonary disease in their medical record, representing 6.3% of all visits to the ED (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

For a complex survey, the design degrees of freedom are calculated by subtracting the number of strata from the number of primary sampling units (PSUs). In an analysis on a subgroup, the degrees of freedom should be based on the number of strata and PSUs containing the observations of interest.  In SUDAAN, by using the PROC DESCRIPT procedure, the user can output the number of strata and PSUs represented in the subpopulation. In other packages, the user may need to calculate the number of PSUs and strata separately.

New Products This Month

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.

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 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 26.8 million visits to the ED made by adults aged 65 and older, representing 20.4% of all visits to the ED. Stomach, abdominal pain, cramps or spasms; and shortness of breath were the two most frequently reported reasons for visit among women aged 65 and older. Shortness of breath and chest pain were the two most frequently reported reasons for visit among men aged 65 and older. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

NAMCS and NHAMCS have separate files of drug ingredients for each year of data, which can be merged with the public use files using a program provided on the survey website.  While each drug on the public use file includes up to four therapeutic categories, combination products are composed of multiple ingredients, and each one of those may have its own therapeutic categories. By adding the drug ingredient file to the main public use file, data users can access this additional information which is year- and survey-specific.

New Products This Month

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 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).

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 2020 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2020, there were approximately 8.2 million injury visits to the ED made annually by children and adolescents aged 18 and younger. 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 . . .

When using SUDAAN remember to sort your input dataset by the design variables specified on the NEST statement. Your analysis dataset should be sorted in SAS by the strata and cluster variables before calling any SUDAAN procedures.

New Products This Month

The 2020 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 National Minority Mental Health Awareness Month (July), we present estimates for visits to emergency departments (ED) related to mental health from the x.

• In 2019, approximately 15.6 million visits were made to the ED by patients with a diagnosis of a mental health disorder, accounting for 10.4% of all ED visits or 48 visits per 1,000 people. Rates of visits related to mental health disorders were higher among non-Hispanic black people (85 visits per 1,000 people) compared with non-Hispanic white people (51 visits per 1,000 people), Hispanic people (27 visits per 1,000 people) and non-Hispanic people of other races (22 visits per 1,000 people). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

To properly account for the sample design and obtain correct variance estimates, all patient visits with a positive sample weight should be included in your analysis. It is important not to drop any records from your dataset; for example, do not use an “IF” to subset your data. Instead, SAS provides domain or subgroup analysis, which allows you to include all observations while focusing on the subgroup of interest. It is also important to retain records with missing values for the variable of interest. To do this using SAS, always include NOMCAR in the PROC SURVEYFREQ statement to allow the missing values to be included in the standard error computations.

New Products This Month

2020 NAMCS COMMUNITY HEALTH CENTER SUMMARY TABLES – The Ambulatory and Hospital Care Statistics Branch is pleased to release the most current nationally representative data on visits to hospital community health centers (CHC) in the United States. Estimates are presented on selected patient, and visit characteristics using data collected in the 2020 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.

Stats of the Month

In recognition of National Safety Month, we present estimates for visits to emergency departments (ED) for injures from the 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2019, approximately 23 million visits were made to the ED by patients with a primary diagnosis of injury*, accounting for 15.2% of all ED visits. Among visits for injuries, visits made for injury of the head were the most frequent (26% of the injury visits) followed by injury of the hand, wrist or fingers (15% of the injury visits).  (Estimates from the Public Use File)

* defined as visits with a primary diagnosis of injury (International Classification of Diseases, 10th Revision, Clinical Modification, codes S00–T34)

Data Tip of the Month

Did you know . . .

When combining multiple years of NAMCS or NHAMCS data, you can produce averaged annual estimates by doing the following: create a new weight variable by dividing the patient visit weight (PATWT) by the number of the years in your analysis (e.g., if combining 3 years of data, new variable PATWT3=PATWT/3).

New Products This Month

• A visit-level file based on 2020 NAMCS Community Health Center data is available for use in the NCHS Research Data Center (RDC). Please see the RDC file data dictionary, visit the RDC website, or contact the Ambulatory and Hospital Care Statistics Branch at ambcare@cdc.gov or 301-458-4600 for more information.
• 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 [PDF – 428 KB]. 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.

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 Women’s Health Week (May 8-14), we present estimates for visits to emergency departments (ED) by women from the 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2019, approximately 66 million visits were made to the ED by women aged 18 and over, accounting for 56.9% of all ED visits made by adults. Almost half of the visits by women were made by women aged 18-44 (49.4% of all ED visits by women). Women aged 45-64 accounted for 26.4%  of the ED visits made by women and women aged 65 and over accounted for 24.2% of the ED visits by women. Stomach and abdominal pain, cramps and spasms was the most frequent reason for visit among women aged 18-44 whereas chest pain was the most frequent reason for visits among women aged 45 and over. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

Starting in 2014, up to 30 drugs are collected per visit in NAMCS and NHAMCS. Each MED code is associated with a DRUGID code (MED1 and DRUGID1, MED2 and DRUGID2, etc.). The MED code, based on an NCHS classification, represents the drug entry as reported in the survey instrument and can include brand names, generic names, or therapeutic effects (such as allergy relief). The DRUGID code, based on a proprietary classification, represents the generic composition of the drug. Each DRUGID can be associated with up to 4 therapeutic categories. For example, MED1 is assigned to DRUGID1, which is associated with RX1CAT1, RX1CAT2, RX1CAT3, RX1CAT4. These RXCAT variables will always reflect the highest level therapeutic code available. SAS exercises on how to use the drug variables could be found here [PDF – 95 KB].

New Products This Month

• The 2015 NAMCS Community Health Center Public Use Data File and documentation are now available for downloading, along with SAS, Stata, and SPSS files for reading and formatting the data.
• 2015 NAMCS COMMUNITY HEALTH CENTER WEB TABLES [PDF – 1,063 KB] – The Ambulatory and Hospital Care Statistics Branch is pleased to release nationally representative data on ambulatory care visits to community health centers in the United States. Estimates are presented on selected provider, patient, and visit characteristics using data collected in the 2015 NAMCS Community Health Center component.
• The 2021 NEHRS public use data files and documentation [PDF – 355 KB] are now available for downloading. We provide pre-made SAS and Stata datasets. The 2021 NEHRS will be the last fielding of this survey. More information is on the main NEHRS website.

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 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2019, approximately 26.2 million visits were made to the ED by Hispanic or Latino people, accounting for 17.4% of all ED visits; 34.8 million visits were made by non-Hispanic Black people, accounting for 23.1% of all ED visits; and 5.6 million visits were made by non-Hispanic other* people, accounting for 3.7% 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 . . .

When using NAMCS or NHAMCS annual public use data file documentation, you will sometimes find web links to other documents located on the NCHS FTP server.  But when you click them, the link is broken.  That’s because NCHS changed its FTP address and these older links will no longer work.  There is an easy work-around, however.  The steps may vary slightly depending on your browser, but the logic is the same:  Simply right click on the ‘bad’ link from the documentation and copy the hyperlink to your browser’s URL line.  Change just the initial “ftp” in the URL address to “https”, and it should work correctly in most cases.  There is an extra step to take when using older links pointing to the 2018 NHAMCS Public Use File Documentation. (Such links are included in Appendix II and Appendix III of the 2018 NAMCS Public Use File Documentation.) Not only the initial “ftp” in the URL address should be changed to “https” but also the file name should be changed to doc18-ed-508.

New Products This Month

• 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 Quickstat 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 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.
• 2019 NHAMCS EMERGENCY DEPARTMENT SUMMARY WEB TABLES [PDF – 805 KB] – The Ambulatory and Hospital Care Statistics Branch is pleased to release the most current nationally representative data on ambulatory care visits to hospital emergency departments (ED) in the United States. Estimates are presented on selected hospital, patient, and visit characteristics using data collected in the 2019 NHAMCS.

Data Tell Stories

Denzel Zhu is a medical student and research fellow at Albert Einstein College of Medicine. His research focuses on genitourinary cancer epidemiology, urologic oncology, and kidney stone disease. His recent work used data from NHAMCS to understand predictors for opioid prescriptions by ED physicians/providers for the treatment of kidney stone pain (nephrolithiasis). The manuscript entitled “National Trends and Prescription Patterns in Opiate Analgesia for Urolithiasis Presenting to Emergency Departments: Analysis of the National Hospital Ambulatory Medical Care Survey, 2006-2018” was published in the journal Urology and can be found here.

After utilizing NHAMCS data, Mr. Zhu shared these insights with us:

1. What is novel or publicity-worthy about this research? This is the first literature work analyzing the NHAMC database – a  national database – to analyze temporal and geographic patterns of ED prescriptions across the US for narcotics for patients presenting with nephrolithiasis. Very little has been published, in general, looking at geographic differences for these prescription patterns in urology.
2. How does this research change what is known about this area of research? – It highlights a trend suggesting that emergency rooms in the midwestern region of the US may be more likely to prescribe opioids for patients presenting with nephrolithiasis compared to other regions of the US, and that urban emergency rooms are more likely to prescribe narcotics compared to rural emergency rooms. Urologists who consult or treat patients in these areas may need to evaluate their relationship and educational efforts with emergency room providers in these locations surrounding minimizing narcotic prescriptions for nephrolithiasis.
3. What, if any, is the potential public health relevance of this research? – We all have a responsibility to reduce opioid prescriptions as much as possible in medicine. Given the answer to #2 above, there is a role to focus on this even from the time a patient presents to the emergency room with a symptomatic kidney stone. We should seek alternative treatments aside from narcotics and be mindful of geographic patterns for higher opioid prescription tendencies for this common condition in urology.

Congratulations to Denzel Zhu and his co-authors and thanks for sharing this story with us!

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 Kidney Month (March) we present estimates for visits to emergency departments (ED) for chronic kidney disease (CKD)  from the 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2019, adult patients with CKD documented in the medical record accounted for 4.3% of all visits to the ED made by adults aged 18 and over.  The percentage of visits made by adult patients with CKD in the medical record increased with age. More visits were made by adults aged 65 and over (10.9%) compared with adults aged 45-64 (4.7%) and 18-44 (0.7%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

If you wish to link visit characteristics with providers and produce aggregated statistics at the provider level you could follow these steps:

• • 1. Organize the data in a DATA step, converting missing values for continuous variables to ‘.’ and creating 0, 1 variables out of categorical variables where necessary
    2. Use PROC SUMMARY (or PROC MEANS) to create one record per provider along with the aggregate statistics for that provider.
    3. Clean up the output file by converting proportions to percentages.

SAS code examples can be found here [PDF – 53 KB].

New Products This Month

Cairns C, Ashman JJ, Kang K. Emergency Department Visit Rates by Selected Characteristics: United States, 2019 [PDF – 425 KB]. NCHS Data Brief, no 434. Hyattsville, MD: National Center for Health Statistics. 2021.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 under 1 year of age (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.

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 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• Santo L, Peters ZJ, DeFrances CJ. Emergency department visits among adults with mental health disorders: United States, 2017–2019. NCHS Data Brief, no 426. Hyattsville, MD: National Center for Health Statistics. 2021. This report shows that the ED visit rate for mental health disorders was higher among younger adults than older adults.  A higher percentage of adult ED visits made by patients with mental health disorders had visits lasting 4 hours or more than visits made by patients without mental health disorders. A higher percentage of adult ED visits made by patients aged 18–44 with mental health disorders resulted in hospital admission than visits made by patients without mental health disorders.
• 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 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.

Data Tip of the Month

Did you know . . .

A new version of the 2019 NHAMCS Emergency Department public use data file was released which includes the ED weight variable (EDWT) only on the first record for each hospital (based on the HOSPCODE variable).  The initial file release included this variable on all ED records.  It is easier to produce facility-level estimates when the EDWT variable is present on only one record for each ED, and that is the way the file has traditionally been released.  To calculate facility-level estimates correctly, it is recommended that the revised version of the file be downloaded.  Visit-level estimates are unaffected.  Pre-made SAS, SPSS, and Stata datasets have also been updated to reflect this change.

New Products This Month

QuickStats: Rates 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 Quickstat shows that during 2017–2019, 52.9 ED 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.

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 2021, the 2018 NAMCS public use data file and documentation and the 2019 NHAMCS Emergency Department public use data file and documentation were also made available for downloading, along with SAS, Stata, and SPSS files for reading and formatting the data. Restricted data files may be accessed through the Research Data Center.

For the first time, the National Center for Health Statistics has released public use data files for the National Electronic Health Records Survey (NEHRS). NEHRS is an annual, nationally representative survey of U.S. office-based physicians that collects information on the adoption, use, and interoperability of Electronic Health Record systems. The 2018 NEHRS public use file documentation, and pre-made SAS and Stata datasets are available for download here. 2018 NEHRS weighted estimates are available for download here. The 2019 NEHRS public use file documentation, 2019 pre-made SAS and Stata datasets, 2019 questionnaire, and 2019 data dictionary are available for download here.

Publications from NHAMCS and NAMCS in 2021

NCHS reports, data briefs and quickstats

• Ashman JJ, Cairns C, DeFrances CJ, Schwartzman A. Respiratory illness emergency department visits in the National Hospital Care Survey and the National Hospital Ambulatory Medical Care Survey. National Health Statistics Reports; no 151. Hyattsville, MD: National Center for Health Statistics. 2021. This report compares ED visits for respiratory illness between the 2014 National Hospital Care Survey (NHCS) and the 2014 NHAMCS to determine the potential of researching respiratory illness in EDs with non-nationally representative NHCS data.  The authors found that, although not nationally representative, NHCS provides additional information on ED visits for respiratory illness that is not available elsewhere.
• Cairns C, Ashman JJ, Kang K. Emergency Department Visit Rates by Selected Characteristics: National Hospital Ambulatory Medical Care Survey, United States, 2018. NCHS Data Brief, no 401. Hyattsville, MD: National Center for Health Statistics. 2021. This data brief shows that in 2018, the ED visit rate was 39 visits per 100 persons. The ED visit rate was highest for infants under 1 year of age (101 visits per 100 persons), higher for females than males and higher for non-Hispanic black/African American persons (87 visits per 100 persons) than for persons from all other racial and ethnic groups. The ED visit rate for patients with Medicaid was highest compared to all other sources of payment.
• Santo L, Schappert SM, Ashman JJ. Emergency department visits for influenza and pneumonia: United States, 2016–2018. NCHS Data Brief, no 402. Hyattsville, MD: National Center for Health Statistics. 2021. This data brief shows that in 2016-2018, there were, annually, 7.9 visits per 1,000 persons with pneumonia, 4.4 visits per 1,000 persons with influenza and 12.2 visits per 1,000 persons with either influenza, pneumonia or both. The ED visit rate for patients with influenza and pneumonia was higher among younger children than older children and increased with age among adults. The rate was higher among non-Hispanic black persons compared with persons from other race and ethnicity groups.  It was also higher for persons with Medicare or Medicaid compared with persons with private insurance or uninsured persons.
• Davis D, Cairns C. Emergency Department Visit Rates for Motor Vehicle Crashes by Selected Characteristics: United States, 2017-2018. NCHS Data Brief, no 410. Hyattsville, MD: National Center for Health Statistics. 2021. This data brief uses data from the 2017 and 2018 NHAMCS to examine visit rates to the ED for motor vehicle crash injuries. It shows that the ED visit rates were highest among patients aged 15-24 years, higher for non-Hispanic black patients than non-Hispanic white and Hispanic patients and higher for patients with Medicaid, no insurance, or workers’ compensation than persons with private insurance or Medicare. Finally,  the visit rates at hospitals located in the South were higher than the visit rates at hospitals in all other regions of the United States.
• Lucas CA, Hadley E, Chew R, Nance J, Baumgartner P, Thissen MR, et al. Machine learning for medical coding in healthcare surveys. National Center for Health Statistics. Vital Health Stat 2(189). 2021. This report shows the potential of machine learning models for medical coding by using data from the ED portion of the 2016 and 2017 NHAMCS. The degree of agreement between a model and a human versus two humans on the same set of codes was assessed and, although trained medical coders outperformed the assessed models in assigning correct diagnosis, injury, and reason for visit codes, machine learning models showed promise in assisting with medical coding projects.
• Ashman JJ, Santo L, Okeyode T. Characteristics of office-based physician visits, 2018. NCHS Data Brief, no 408. Hyattsville, MD: National Center for Health Statistics. 2021. This data brief examines visit rates by age and sex. It also examines visit characteristics—including insurance status, reason for visit, and services—by age using data from the 2018 NAMCS.
• QuickStats: Emergency Department Visit Rates for Motor Vehicle Crashes, by Age Group — United States, 2018. MMWR Morb Mortal Wkly Rep 2021;70:106. This quickstats shows that in 2018 there were 10.5 ED visits per 1,000 persons for motor vehicle crashes. Rates were highest among persons aged 15-24 years (18.6) and declined with age to 11.7 for those aged 25–64 years and to 4.2 for those aged ≥65 years.
• QuickStats: Distribution of Hours per Day That Office-Based Primary Care and Specialist Care Physicians Spent Outside Normal Office Hours Documenting Clinical Care in Their Medical Record System† — United States, 2019. MMWR Morb Mortal Wkly Rep 2021;70:1752. This quickstats shows that in 2019, 91.0% of office-based physicians spent time outside normal office hours documenting clinical care: 17.0% spent <1 hour, 41.4% spent 1–2 hours, 24.0% spent >2 hours–4 hours, and 8.6% spent >4 hours per day.

Web tables

• National Hospital Ambulatory Medical Care Survey: 2018 Emergency Department Summary Tables [PDF – 786 KB] – The Ambulatory and Hospital Care Statistics Branch released the most current nationally representative data on ambulatory care visits to hospital EDs in the United States. Estimates are presented on selected hospital, patient, and visit characteristics using data collected in the 2018 NHAMCS.
• National Ambulatory Medical Care Survey: 2018 National Summary Tables [PDF – 703 KB]– The Ambulatory and Hospital Care Statistics Branch released 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 2018 NAMCS.

Manuscripts

• Green PP, Cummings NA, Ward BW, McKnight-Eily LR. Alcohol Screening and Brief Intervention: Office-Based Primary Care Physicians, U.S., 2015-2016. Am J Prev Med. 2022 Feb;62(2):219-226. Epub 2021 Nov 10. This manuscript, using data from the Physician Induction Interview portion of the 2015 and 2016 NAMCS, shows that 28.3% of the primary care physicians (PCPs) reported not screening patients for alcohol misuse. Only 38.0% of PCPs who screened patients reported always conducting brief interventions among their patients who screened positive for risky alcohol use.
• Suls, J., Bayliss, E., Berry, J., Bierman, A., Chrischilles, E., Farhat, T., Fortin, M., Koroukian, S., Quinones, A., Silber, J., Ward, B., Wei, M., Young-Hyman, D. & Klabunde, C. (2021). Measuring multimorbidity: selecting the right instrument for the purpose and the data source. Medical Care, 59 (8), 743-756. In this manuscript the authors cite NAMCS as an example of a public health survey used to measure multimorbidity.
• Ward BW, Sengupta M, DeFrances CJ, Lau DT.
• Am J Public Health. 2021 Dec;111(12):2141-2148. This manuscript discusses how the National Center for Health Statistics had to modify survey operations for several of its provider-based National Health Care Surveys, including NAMCS and NHAMCS, in order to capture the experiences of providing care during the pandemic.

New Products This Month

• Santo L, Peters ZJ, DeFrances CJ. Emergency department visits among adults with mental health disorders: United States, 2017–2019. NCHS Data Brief, no 426. Hyattsville, MD: National Center for Health Statistics. 2021. This report shows that the ED visit rate for mental health disorders was higher among younger adults than older adults.  A higher percentage of adult ED visits made by patients with mental health disorders had visits lasting 4 hours or more than visits made by patients without mental health disorders. A higher percentage of adult ED visits made by patients aged 18–44 with mental health disorders resulted in hospital admission than visits made by patients without mental health disorders.
• 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 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.

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.