Ambulatory Care Monthly News

Stats of the Month

In recognition of National Influenza Vaccination Week (December 5-11), we present estimates for visits to emergency departments (ED) at which an influenza test was provided, from the 2019 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2019, an influenza test was provided at 4.9% of all ED visits. Children younger than 18 were tested for influenza more frequently than adults. Children were tested at 9.4% of ED visits made by children, whereas adults aged 18 and over were tested for influenza at 3.6% of ED visits made by adults. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

In the International Classification of Diseases, 10^th Revision, Clinical Modification (ICD-10-CM), which is used to code NAMCS and NHAMCS data, diagnosis codes can have a maximum of seven digits. For the NHAMCS ED public use file, only the first four digits of the diagnosis codes are included. There is an implied decimal between the third and fourth digits and inapplicable fourth digits are dash-filled. For example: F321 = F32.1 Major depressive disorder, single episode, moderate; I10- = I10 Essential (primary) hypertension. Since ICD-10-CM uses non-numeric characters extensively, we are not able to provide numeric recodes for the diagnosis codes.

New Products This Month

The 2019 NHAMCS ED 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.

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 Diabetes Month (November) we present estimates for diabetes from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, patients with Diabetes Mellitus documented in the medical record accounted for 13.9% of visits to office-based physicians. The percentage of visits made by patients with Diabetes Mellitus increased with age, from 2.6% among patients under 45 years to 25.7% among patients 75 years and over.  (Estimates from table 17).

In recognition of U.S. Antibiotic Awareness Week (November 18-24), we present estimates for antibiotics given or prescribed at discharge at the emergency department from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, cephalosporins and penicillins were among the twenty most frequently mentioned drugs at the ED visits. Cephalosporins were given or prescribed at 9.3 million ED visits (7.1% of all ED visits) and penicillins were given or prescribed at 7.2 million of ED visits (5.6% of all ED visits) (Estimates from table 21 [PDF – 786 KB] and the Public Use File).

Data Tip of the Month

Did you know . . .

Prior to release of the public use data file, NCHS conducts extensive disclosure risk analysis to minimize the chance of any inadvertent disclosure. Based on research conducted by NCHS for 2018 NAMCS, certain variables were subject to masking in some cases and outlier values for certain variables (age, age of pregnant patient, height, weight, number of past visits in last 12 months, and time spent with physician) were top coded in accordance with NCHS confidentiality requirements. Masking was performed in such a way to cause minimal impact on the data; data users who wish to use unmasked data can apply to the NCHS Research Data Center.

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 ADHD awareness month (October) we present estimates for attention deficit hyperactivity disorder (ADHD) from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, there were approximately 8.9 million visits to office-based physicians made by children and youth (age 0-18) with a diagnosis of ADHD in their medical record. Visits made by patients with ADHD  accounted for 6.7% of all visits to office-based physicians made by children and youth. The percentage of visits made by patients with ADHD varied by sex  – it was higher among boys (10.2% of all visits made by boys age 0-18) than girls (3.0% of all visits made by girls age 0-18)  (Estimates from Public Use File).

In recognition of Eye injury prevention month (October) we present estimates for eye injuries from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, there were approximately 574,000 visits to the ED related to eye injury. Visits related to eye injury represent 1.6% of all injury visits and 0.4% of all ED visits.   (Estimates from Public Use File).

Data Tip of the Month

Did you know . . .

State-based estimates can only be calculated using NAMCS data from 2012 through 2015.  The NAMCS sampling design changed in 2012 in order to allow state-based estimates for the 34 most populous states. In 2013, 2014, and 2015, the numbers of targeted states were 22, 18, and 16, respectively. The state weighting variable is called PATWTST; it is only to be used for individual state estimates and will not sum to national or regional estimates.

New Products This Month

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 Emergency Department portion of the 2016 and 2017 National Hospital Ambulatory Medical Care Survey (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 RFV codes, machine learning models showed promise in assisting with medical coding projects.

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

See below for an exciting interview with Dr. Alan Fleischer, a professor at the University of Cincinnati College of Medicine, on how he has been using NAMCS and NHAMCS data.

In recognition of National Cholesterol Education Month (September) we present estimates for hyperlipidemia from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, there were approximately 166.8 million visits to office-based physicians made by adults with a diagnosis of hyperlipidemia documented in their medical record. Visits made by patients with hyperlipidemia accounted for 19.4% of all visits to office-based physicians. The percentage of visits made by patients with hyperlipidemia increased with age from 2.4% among visits made by patients under 45 years to 35.7% among visits made by patients age 75 and over  (Estimates from Table 17 [PDF – 703 KB] and Public Use File).

In recognition of Pain Awareness Month (September)we present estimates for headache from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, headache was among the 10 most frequent principal reasons for visit made by adults to the emergency department (ED). It was the principal reason for visit at approximately 2.9 million visits, representing 2.9% of ED visits made by adults. Women reported headache as the principal reason for visit more frequently than men (3.6% versus 1.9%). (Estimates from Public Use File).

Data Tip of the Month

Did you know . . .

For 2018 NAMCS, the geographic variable REGIONOFF (region where majority of physician’s sampled visits occurred) was removed from the public use file. The only geographic variable remaining on the 2018 public use file is MSA (was physician’s interview location within a metropolitan statistical area). The physician specialty variable SPECR (a 14-category variable denoting broad specialty group), was also removed from the public use file. The remaining physician classification variables are MDDO (doctor of medicine or doctor of osteopathy) and SPECCAT (type of specialty: primary care, surgical care or medical care). The region and physician specialty variables were removed because low survey response in 2018 resulted in the inability to make reliable estimates using these variables.

No New Products This Month

Data Tell Stories

Dr. Alan Fleischer is a professor and residency program director of the Department of Dermatology at the University of Cincinnati College of Medicine. With clinical interests in general dermatology and Hidradenitis Suppurativa, he has conducted extensive research in topic areas such as care gaps and quality of care, changes in treatment over time, climate, emergency department care, health disparities, and characterization of care. A list of his publications can be found here: https://researchdirectory.uc.edu/p/fleiscab

After utilizing NAMCS and NHAMCS data, Dr. Fleischer shared the following responses to these questions:

Q: What led you to utilizing NAMCS and NHAMCS data for your research and how did you first find out about these datasets?

A: We first began using these datasets when Doug Bradham, a health economist, informed Steve and me of the 1990 NAMCS data and made this data available. This led to our first publication: https://pubmed.ncbi.nlm.nih.gov/8288916/

I believe the data then came on tapes and access was challenging.

Q: As opposed to analyzing other data sources, how did our data help answer your research questions?

A: Most of our work has looked first at characterization of care. Over time we have branched into changes in ambulatory care over time, health disparities work, quality of care work, and other studies. These datasets characterize US ambulatory care, and dermatology care in the US is almost exclusively ambulatory. Because these data are easily accessible, we have used them to address many questions. Moreover, racial and ethnicity data are contained within the datasets, so exploring these and other demographic variables has been beneficial.

Q: Would you recommend these datasets to other researchers?

A: Yes, wholeheartedly. If other workers can use cross-sectional complex survey results to answer their questions, this is a great resource. It is not helpful for studies that need longitudinal information about individual patients. As with all datasets, asking questions that can be answered with the data is the pathway to success. Steve Feldman and I have been using these datasets long enough that we have a reasonable understanding of the right questions to ask.

Congratulations to Dr. Fleischer 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 Immunization Awareness Month we present estimates for immunization from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, an immunization was provided at 14.5% of all preventive care visits. The percentage of preventive care visits in which an immunization was provided was higher among children aged 17 and younger (42.9%) than adults aged 18 and older (5.3%). (Estimates from the Public Use File)

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 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, there were approximately 9.2 million injury visits to the ED made annually by children and adolescents aged 18 and younger. Among these visits, 1.1% were made for injury of the eye or orbit. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

The emergency departments weights (EDWT) enable data users to calculate department-level estimates. There is generally one weight for each emergency department which appears on the first visit record only for that department. When running an analysis of facility-level characteristics using EDWT, it is recommended to select only those records where EDWT is greater than zero. This will result in correct sample counts of variables, which is useful for assessing reliability. Weighted estimates will be correct either way, because of the one weight per department format.

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 World Hepatitis Day (July 28) we present estimates for Hepatitis from the 2018 National Ambulatory Medical Care Survey (NAMCS) and from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, there were approximately 2.8 million visits to office-based physicians made by adults with a diagnosis of Hepatitis B and 3.7 million visits made by adults with a diagnosis of Hepatitis C documented in their medical record. Visits made by patients with Hepatitis B accounted for 0.4% of all office-based physician visits made by adults and visits made by patients with Hepatitis C accounted for 0.5% of all office-based physician visits made by adults. The percentage of visits made by patients with Hepatitis C was higher among patients aged 45-74 (0.8%) than 18-44 (0.1%) and 75 and older (0.3%). (Estimates from the In 2018, there were approximately 140,000 visits to the emergency department (ED) made by adults with a diagnosis of viral hepatitis in their medical record, representing 0.1% of the ED visits made by adults. (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

When using SAS, to properly calculate the standard errors (SE) of your statistics (such as means and percentages), the Taylor series linearization method requires information on all records with a non-zero value for your weight variable.

You should never drop observations from a SAS dataset. It is recommended instead to use the DOMAIN statement or the TABLES statement to specify your population of interest. It is recommended to include the NOMCAR option (when using PROC SURVEYFREQ, SURVEYMEANS, SURVEYREG, and SURVEYLOGISTIC) so that records with missing data are included in SE computations. Without NOMCAR, these records are excluded by default and SEs are understated.

New Products This Month

National Ambulatory Medical Care Survey: 2018 National Summary Tables [703 KB] – 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 2018 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.

Notice to Data Users

It has recently come to our attention that some people are having trouble downloading NAMCS and NHAMCS public use data files and documentation from the ftp server on the NCHS website.  Until this issue can be resolved, please do the following: Replace the “ftp” part at the beginning of the URL with “https”.

For example, instead of using:
ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NAMCS/sas/ to access pre-made NAMCS SAS datasets, use this: https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NAMCS/sas/

Also, NCHS no longer uses Internet Explorer; for best results, it is recommended that you use either Google Chrome or Microsoft Edge when accessing NCHS webpages.  If you have questions, please contact the Ambulatory and Hospital Care Statistics Branch at 301-458-4600 or ambcare@cdc.gov.

Stats of the Month

In recognition of Alzheimer’s & Brain Awareness Month (June), we present estimates for visits to office-based physicians by adults with a documented diagnosis of Alzheimer’s disease from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, approximately 6.2 million visits were made to office-based physicians by adults with Alzheimer’s disease, accounting for 0.8 % of all visits to office-based physicians. Visits made by adults with Alzheimer’s disease were higher among adults aged 75 and over (2.7% of the visits made by adults aged 75 and over) than among adults 74 and younger (0.4% of the visits made by adults age 18-74) (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

For the first time in 2018, NAMCS weights were adjusted using Multipurpose Iterative Proportional Fitting (IPF). This is a calibration technique that simultaneously implements (1) calibration in multiple specified domains; (2) nonresponse adjustment; and (3) weight trimming, as part of a unified iteration cycle. As the method used to weight NAMCS data has changed with 2018 data, caution should be taken when interpreting differences between the 2016 and 2018 estimates. More details can be found in the 2018 NAMCS documentation.

New Products This Month

• 2018 NHAMCS Emergency Department Summary Web Tables – 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 2018 NHAMCS.
• 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 2017-2018 National Hospital Ambulatory Medical Care Survey (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.

Data Tell Stories

Dr. Matthew Growdon, University of California, San Francisco, along with colleagues Siqi Gan, Dr. Kristine Yaffee and Dr. Michael Steinman, recently published a paper which used 2014-2016 NAMCS data: Polypharmacy among older adults with dementia compared with those without dementia in the United States

They found that persons with dementia (PWD) had significantly higher odds of being prescribed at least five or at least ten medications compared to PWOD. While the largest sources of medications among PWD were cardiovascular and central nervous system medications, PWD were generally prescribed a wide range of medications and had higher odds of receiving at least one highly sedating or anticholinergic medication compared to PWOD. These results highlight the extent of polypharmacy among PWD in the United States.

Dr. Growdon shared the following responses to our questions:

Q: Was this your first time analyzing data from NCHS?

A: Yes–I was very happy to have this opportunity to learn about the wealth of data resources that are made available by NCHS and can be used for independent research and analyses.

Q: What led you to utilizing the NAMCS dataset for your research and how did you find out about NAMCS?

A: My mentor, Dr. Mike Steinman, is an experienced health services researcher who guided me to NAMCS as a potential resource to answer our questions about the role of polypharmacy among people living with dementia in the US. He and many other health services researchers have found NAMCS and other datasets from NCHS to be very helpful for answering a wide variety of research questions.

Q: As opposed to analyzing other data sources, how did NAMCS help answer your research question?

A: NAMCS provides the unique opportunity to derive nationally representative estimates regarding activities taking place in office-based medical visits in the US. We were drawn to the data set given that it is publicly available in an intuitive format for analysis and because it allowed us to derive national estimates regarding prescribing practices as opposed to many other data sources that involved less representative study populations.

Q: Would you recommend NAMCS to other researchers?

A: Yes, definitely! The data are readily accessible online, the documentation is clear and helpful for running analyses in a variety of statistical packages, and staff at NCHS are extremely helpful in troubleshooting and answering questions should you run into problems. 

Congratulations to Dr. Growdon 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 Arthritis Awareness Month (May), we present estimates for visits to office-based physicians by adults 18 and over with a documented diagnosis of arthritis from the 2018 National Ambulatory Medical Care Survey (NAMCS).

• In 2018, approximately 97.8 million visits were made to office-based physicians by adults 18 and over with a documented diagnosis of arthritis, accounting for 13.4% of all visits to office-based physicians.  The percentage was lowest among visits by adults 18-44, with 3.9% of those visits including a documented diagnosis of arthritis.  For visits by older adults, corresponding percentages with arthritis were 13.5% of visits among adults 45-64 years, 17.5% of visits among adults 65-74 years, and 22.5% of visits among adults aged 75 years and over.  (Estimates from the Public Use File)

In recognition of National Mental Health Month (May), we present estimates for visits to hospital emergency departments by patients with a documented diagnosis of depression from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, approximately 13.9 million visits were made to hospital emergency departments by adults 18 and over with a documented diagnosis of depression, accounting for 13.8% of all visits to hospital emergency departments. The percentage was higher among visits by women (16.1% of all visits by women included a documented diagnosis of depression) compared with visits by men (10.7% of all visits by men included a documented diagnosis of depression). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

In addition to the standard drug data included on public use files each year, separate files are available that can be used to add ingredient information for combination drug products. Combination products such as cold preparations on the public use file may only have a therapeutic category of a respiratory combination, for example. By merging the drug ingredient file to the regular public use file, each combination drug can have up to 6 separate ingredients listed with up to 4 therapeutic categories for each one.  Both a SAS program to add the drug ingredients and a data file for merging are produced annually and are available for downloading for use with NAMCS and NHAMCS data.

New Products This Month

• The 2018 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.
• 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 National Ambulatory Medical Care Survey (NAMCS).

Stats of the Month

In recognition of National Minority Health Month (April), we present estimates for visits to the emergency department (ED) by patient race and ethnicity from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, approximately 21.4 million visits were made to the ED by Hispanic or Latino persons, accounting for 16.5% of all ED visits; 34.5 million visits were made by non-Hispanic black persons, accounting for 26.5% of all ED visits; and 5 million visits were made by non-Hispanic other* persons, accounting for 3.9% of all ED visits. (Estimates from the Public Use File)

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

Data Tip of the Month

Did you know . . .

Starting in 2011, NAMCS and NHAMCS data files have been converted into a zipped (compressed) format which must be uncompressed prior to use. To download and uncompress the zipped files: 1) Create a new folder on your location workstation, if desired, to house the files; 2) Click on the file name from the FTP server here: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Datasets/NHAMCS or ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Datasets/NAMCS and follow the prompts to save the file to your desired location; 3) Right-click on the name of the compressed file from your directory screen. On the pop-up menu, there should be an option to extract the file to a location of your choosing.

Beginning with 1999, NHAMCS and NAMCS documentation has been produced as a single file in PDF format which can be viewed or downloaded here. These files are not compressed.

New Products This Month

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.

Stats of the Month

In recognition of National Kidney Month (March), we present estimates for visits to the emergency department (ED) for chronic kidney disease (CKD) from the 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, adult patients with CKD documented in the medical record accounted for 4.4% 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 (5.2%) than women (3.8%) and more visits were made by adults aged 65 and over (12.1%) than younger adults aged 45-64 (3.7%) and 18-44 (1.0%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

NAMCS and NHAMCS data for estimated numbers of visits and visit rates are considered to be reliable if two conditions are met. The first condition is that each estimate is based on at least 30 sample (unweighted) records. If an estimate is based on < 30 cases it is considered unreliable. The second condition is that the weighted data have a relative standard error (RSE) of 30 percent or less. The RSE is equal to the standard error divided by the estimate and expressed as a percent.

Proportion estimates are considered to be unreliable based on the procedure specified in “National Center for Health Statistics Data Presentation Standards for Proportions [PDF – 1.43 MB]” . These standards are based on a minimum denominator sample size and on the absolute and relative widths of a confidence interval calculated using the Clopper-Pearson method.

New Products This Month

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 emergency department (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.

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 2018 National Hospital Ambulatory Medical Care Survey (NHAMCS).

• In 2018, patients with coronary artery disease, ischemic heart disease, or history of MI documented in the medical record accounted for 9.2% 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 2.4% of ED visits made by adults aged 18-54, 16.7% of ED visits made by adults aged 55-74 and 28% of ED visits made by adults aged 75 and over. (Estimates from the Public Use File)
• In 2018, chest pain and related symptoms was the primary reason for visit in 6.7% 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 55-74 (8.3%) than among adults aged 18-54 (6.2%) and adults aged 75 and over (5.5%). (Estimates from the Public Use File)

Data Tip of the Month

Did you know . . .

When performing trend analysis and/or combining multiple years of data, it is important to check that the variables of interest were collected the same way for all of the years contained in your analysis. For example, the number of drugs that are collected has increased over time: from 5 in 1994 to 6 in 1995 to 8 in 2003 to 10 in 2012 and to 30 in 2014. If an increase is observed in the number of medications prescribed, this could be due to the increase in the number of drugs collected in the survey and not an actual increase in prescribing patterns. Therefore, a trend examining prescribing from 2000-2018 should only include the first six listed drugs in all years. You can review the survey instruments for NAMCS and NHAMCS.

New Products This Month

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 emergency department 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.

Year in Review

In 2020, 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 2020, the 2018 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.

Publications from NHAMCS and NAMCS in 2020

NCHS reports and data briefs

• Santo L, Rui P, Ashman JJ.  Physician office visits at which benzodiazepines were prescribed: Findings from 2014–2016 National Ambulatory Medical Care Survey. [ PDF – 376 KB] National Health Statistics Reports; no 137. Hyattsville, MD: National Center for Health Statistics. 2020. This report describes visits to office-based physicians made by adult patients at which benzodiazepines were prescribed, including visits where opioids were coprescribed.
• Davis D, Rui P. Urban-rural differences in visits to office-based physicians by adults with hypertension: United States, 2014–2016 [PDF – 276 KB]. National Health Statistics Reports; no 147. Hyattsville, MD: National Center for Health Statistics. 2020. This report describes urban-rural differences in office-based physician visits made by adults aged 18 and over with documented hypertension by age, sex, and race and ethnicity during 2014–2016.

Manuscripts

• Santo L, Ward BW, Rui P, Ashman JJ.  Antineoplastic drugs prescription during visits by adult cancer patients with comorbidities: findings from the 2010-2016 National Ambulatory Medical Care Survey. Cancer Causes Control. 2020 Feb 21. doi: 10.1007/s10552-020-01281-5.  This manuscript uses 2010-2016 National Ambulatory Medical Care Survey to describe the frequency of comorbidities at visits by patients with breast, prostate, colorectal, and lung cancer and the frequency of a prescription for antineoplastic drugs being included in the treatment received at visits by patients with cancer and concomitant comorbidities. The authors show that among US visits by adult patients with breast, prostate, colorectal, or lung cancer, 56.3% were by patients with ≥ 1 comorbidity. Hypertension was the most frequently observed comorbidity (37.7%), followed by hyperlipidemia (19.0%) and diabetes (12.3%). Antineoplastic drugs were prescribed in 33.5% of the visits.
• Santo L, Schappert SM, Hootman JM, Helmick CG. Arthritis Care Res (Hoboken). 2020 Sep 16. doi: 10.1002/acr.24447. Online ahead of print. PMID: 32937030. Trends in office visits during which opioids were prescribed for adults with arthritis: United States, 2006-2015.  This manuscript investigates national trends in opioid prescriptions during visits to office‐based physicians made by adults with arthritis in the US from 2006 to 2015. The analysis shows that office visits for arthritis increased from 2006 to 2015 and the proportion of those visits with opioids prescribed increased as well.
• Ward BW, Myrick KL, Cherry DK. Physician specialty and office visits made by adults with diagnosed multiple chronic conditions: United States, 2014-2015. Public Health Reports. 2020. Epub ahead of print. doi: 10.1177/0033354920913005. This manuscript uses 2014-2015 National Ambulatory Medical Care Survey to describe visits to office‐based physicians made by adults with multiple chronic conditions in the US.  The analysis shows that 40.0% of physician office visits were made by adults with multiple chronic conditions. Among visits by adults with multiple chronic conditions a higher percentage of visits were to specialists in cardiovascular disease (74.7%) and internal medicine (57.6%).

Publications from NHAMCS in 2020

NCHS reports, data briefs and quickstats

• Rui P, Santo L, Ashman JJ. Trends in opioids prescribed at discharge from emergency departments among adults: United States, 2006–2017 [PDF – 369 KB]. National Health Statistics Reports; no 135. Hyattsville, MD: National Center for Health Statistics. 2020. This report describes trends in ED visits made by adult patients at which opioids were prescribed at discharge from 2006-2007 to 2016-2017.
• Ashman JJ, Schappert SM, Santo L. Emergency department visits among adults aged 60 and over: United States, 2014–2017. NCHS Data Brief, no 367. Hyattsville, MD: National Center for Health Statistics. 2020. This report describes ED visits made by adults aged 60 and over by selected characteristics and by age.
• Jackson G, Brown AM, DeFrances C. Opioid-involved emergency department visits in the National Hospital Care Survey and the National Hospital Ambulatory Medical Care Survey [PDF – 402 KB]. National Health Statistics Reports; no 149. Hyattsville, MD: National Center for Health Statistics. 2020. This report compares 2014 National Hospital Care Survey (NHCS) emergency department (ED) data with national estimates of ED visits due to opioid use from the 2013–2015 National Hospital Ambulatory Medical Care Survey to determine the potential of researching the impact and outcomes of opioid use on hospital EDs with non-nationally representative NHCS data.
• QuickStats: Percentage of Emergency Department Visits for Pain at Which Opioids Were Given or Prescribed, by Geographic Region of the Hospital — United States, 2005–2017. MMWR Morb Mortal Wkly Rep 2020;69:53.
• QuickStats: Percentage of Emergency Department Visits for Acute Viral Upper Respiratory Tract Infection at Which an Antimicrobial Was Given or Prescribed, by Age — United States, 2010–2017. MMWR Morb Mortal Wkly Rep 2020;69:174.
• QuickStats: Emergency Department Visit Rates Related to Mental Health Disorders, by Age Group and Sex — National Hospital Ambulatory Medical Care Survey, United States,§ 2016–2018. MMWR Morb Mortal Wkly Rep 2020;69:1838.
• QuickStats :Percentage of Emergency Department (ED) Visits Made by Adults with Influenza and Pneumonia That Resulted in Hospital Admission, by Age Group — United States 2017–2018. MMWR Morb Mortal Wkly Rep 2020;69:1878.
• QuickStats: Rate of Emergency Department (ED) Visits, by Homeless Status and Geographic Region — National Hospital Ambulatory Medical Care Survey, United States, 2015–2018. MMWR Morb Mortal Wkly Rep 2020;69:1931. 

Web tables

• 2017 NHAMCS EMERGENCY DEPARTMENT SUMMARY WEB TABLES [PDF – 386 KB] – The 2017 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 2017 NHAMCS.

New Products This Month

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 [PDF – 993 KB]. National Health Statistics Reports; no 151. Hyattsville, MD: National Center for Health Statistics. 2021. This report compares emergency department (ED) visits for respiratory illness between the 2014 National Hospital Care Survey (NHCS) and the 2014 National Hospital Ambulatory Medical Care Survey (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.

Data Tell Stories

Tell Us Yours! 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.