The healthcare system in the U.S., particularly outpatient, office-based care, has been shifting toward service delivery by advanced practice providers, particularly nurse practitioners (NPs) and physician assistants (PAs). The National Ambulatory Medical Care Survey (NAMCS), conducted by the National Center for Health Statistics (NCHS) at the Centers for Disease Control and Prevention, is the leading source of nationally representative data on care delivered by office-based physicians. This paper first describes NAMCS, then discusses key NAMCS expansion efforts, and finally presents major findings from two exploratory studies that assess the feasibility of collecting data from NPs and PAs as sampled providers in NAMCS. The first NAMCS expansion effort began in 2006 when the NAMCS sample was expanded to include community health centers and started collecting and disseminating data on physicians, NPs, PAs, and nurse midwives in these settings. Then, in 2013, NCHS included workforce questions in NAMCS on the composition and clinical tasks of all healthcare staff in physician offices. Finally, in 2013-2014, NCHS conducted two exploratory studies and found that collecting data from NPs and PAs as sampled providers in NAMCS is feasible. However, modifications to the current NAMCS procedures may be necessary, for example, changing recruitment strategies, visit sampling procedures, and physician-centric survey items. Collectively, these NCHS initiatives are important for healthcare research, practice, and policy communities in their efforts toward providing a more complete picture of the changing outpatient, office-based workforce, team-based care approach, and service utilization in the U.S.

The Centers for Disease Control and Prevention's (CDC's) National Center for Health Statistics (NCHS) is committed to collecting and disseminating high-quality data that meet the information needs of a wide range of users. We take issue with the unfavorable assessment of National Hospital Ambulatory Medical Care Survey (NHAMCS) data in a recent editorial by Cooper1 and appreciate the opportunity to respond to her comments. | We agree with Cooper1 that research findings need to be critically assessed, and we appreciate the guidelines she provides for potential authors using NHAMCS data, which are consistent with our recent article.2 We are troubled, however, by her sweeping indictment of the NHAMCS data-gathering process and her concern that medical practice or policy may have changed based on “the false assumption that the data were valid.”1 In fact, the authors cited by Cooper1 appropriately assessed the limitations of using NHAMCS data3, 4, 5, 6 and reported that their findings3, 4, 5 were consistent with previous research. In cases in which findings from studies diverge, it is important to consider the methodology of each study. A particular strength of NHAMCS is that it includes hospitals other than academic medical centers, which commonly serve as the settings for research studies, thereby giving a more complete picture of health care use patterns. When comparing data from NHAMCS with other studies, one should always be careful to keep such methodological differences in mind before making conclusions about validity.

The National Hospital Ambulatory Medical Care Survey (NHAMCS) is widely used for medical research. Nearly 500 articles have been published based on this database, including 28 in Annals of Emergency Medicine. NHAMCS is a national probability sample survey of visits to emergency and outpatient departments in nonfederal, general, and short-stay hospitals, conducted by the Centers for Disease Control and Prevention, National Center for Health Statistics (http://www.cdc.gov/nchs/ahcd.htm). Strengths of the NHAMCS survey are its rigorous methodology, nationally representative nature, large size, wide array of variables, and capacity to examine long-term trends. Investigators can freely download the database and test locally developed hypotheses. Challenges with NHAMCS are that, given its logistic and statistical complexity, resulting research can be difficult for readers to interpret and for editors and reviewers to critique. There are important limitations and caveats to this survey that, if overlooked, could lead to misleading or inaccurate conclusions. In this article, we have a posed a series of questions to 2 NHAMCS statisticians, and we believe that their answers will be invaluable to both NHAMCS investigators and readers of its research.

KEY FINDINGS: The number of noninjury emergency department (ED) visits in which abdominal pain was the primary reason for the visit increased 31.8%. The percentage of ED visits for which chest pain was the primary reason decreased 10.0%. Use of advanced medical imaging increased strongly for ED visits related to abdominal pain (122.6%) and chest pain (367.6%). The percentage of ED visits for chest pain that resulted in a diagnosis of acute coronary syndrome decreased 44.9%.

OBJECTIVES: To establish current estimates and project potential reductions in the volume and cost of annual Pap tests administered at visits to physician office and hospital outpatient departments in light of cervical cancer screening changes and HPV vaccination. STUDY DESIGN: Assessment of baseline national administrative data and future projection. METHODS: We used data from the National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS) to analyze physician office and hospital outpatient department visits made by female subjects 15 years and older from 2003 through 2005. RESULTS: Pap tests were ordered annually at 30.2 million physician office and hospital outpatient department visits in the United States from 2003 through 2005. Among visits by young women aged 15 to 26 years, Pap tests were ordered at 5.8 million visits each year, representing 19.3% of all Pap tests ordered. Among visits made by women of childbearing age that included Pap tests, 76.0% occurred in obstetrics and gynecology offices or clinics. Using a simple projection model, we estimated an overall annual decrease of 1.2 million Pap tests for young women aged 15 to 26 years and a corresponding cost reduction of $77.6 million after routine HPV vaccination and HPV DNA testing. Among female subjects 15 years and older, the estimated potential decrease in Pap tests was 6.3 million, with an estimated $403.8 million in cost reduction. CONCLUSIONS: The NAMCS and NHAMCS provide baseline data to estimate the effects of HPV vaccination and HPV DNA testing on cervical cancer screening policy. These future technologies may result in changes to cervical cancer screening policies and, when fully accepted and implemented, may reduce economic costs associated with cervical cancer in the United States.

The 2009 Academic Emergency Medicine consensus conference focused on "Public Health in the ED: Surveillance, Screening and Intervention." One conference breakout session discussed the significant research value of health-related data sets. This article represents the proceedings from that session, primarily focusing on emergency department (ED)-related data sets and includes examples of the use of a data set based on ED visits for research purposes. It discusses types of ED-related data sets available, highlights barriers to research use of ED-related data sets, and notes limitations of these data sets. The paper highlights future directions and challenges to using these important sources of data for research, including identification of five main needs related to enhancing the use of ED-related data sets. These are 1) electronic linkage of initial and follow-up ED visits and linkage of information about ED visits to other outcomes, including costs of care, while maintaining de-identification of the data; 2) timely data access with minimal barriers; 3) complete data collection for clinically relevant and/or historical data elements, such as the external cause-of-injury code; 4) easy access to data that can be parsed into smaller jurisdictions (such as states) for policy and/or research purposes, while maintaining confidentiality; and 5) linkages between health survey data and health claims data. ED-related data sets contain much data collected directly from health care facilities, individual patient records, and multiple other sources that have significant potential impact for studying and improving the health of individuals and the population.