The Results Are Only as Good as the Sample: Assessing Three National Physician Sampling Frames

Abstract

BACKGROUND: Databases of practicing physicians are important for studies that require sampling physicians or counting the physician population in a given area. However, little is known about how the three main sampling frames differ from each other. OBJECTIVE: Our purpose was to compare the National Provider and Plan Enumeration System (NPPES), the American Medical Association Masterfile and the SK&A physician file. METHODS: We randomly sampled 3000 physicians from the NPPES (500 in six specialties). We conducted two-and three-way comparisons across three databases to determine the extent to which they matched on address and specialty. In addition, we randomly selected 1200 physicians (200 per specialty) for telephone verification. KEY RESULTS: One thousand, six hundred and fiftyfive physicians (55 %) were found in all three data files. The SK&A data file had the highest rate of missing physicians when compared to the NPPES, and varied by specialty (50 % in radiology vs. 28 % in cardiology). NPPES and SK&A had the highest rates of matching mailing address information, while the AMA Masterfile had low rates compared with the NPPES. We were able to confirm 65 % of physicians' address information by phone. The NPPES and SK&A had similar rates of correct address information in phone verification (72-94 % and 79-92 %, respectively, across specialties), while the AMA Masterfile had significantly lower rates of correct address information across all specialties (32-54 % across specialties). CONCLUSIONS: None of the data files in this study were perfect; the fact that we were unable to reach one-third of our telephone verification sample is troubling. However, the study offers some encouragement for researchers conducting physician surveys. The NPPES and to a lesser extent, the SK&A file, appear to provide reasonably accurate, up-to-date address information for physicians billing public and provider insurers.

Telephone vs. Web-based prescreening predicts early but not overall physician response to a mailed survey

“…Physicians who were pre-screened via telephone were more likely to respond early, which may reflect “priming” through direct contact with office staff or an indication of overall ease of access to the physician. Consistent with prior reports [5], less than a third of potential respondents were found eligible after telephone prescreening. Although Web-based prescreening is not a perfect substitute for telephone prescreening, it can be used in place of telephone prescreening as long as researchers follow-up with nonrespondents.…”

Physician Multisite Practicing: Impact on Access to Care

“…However, collection of data regarding physician practice locations has been inconsistent, mixed with public/private initiatives with variable completeness and data quality. 2–5 National estimates are insufficient to assess the specific future workforce needs of state and local areas. For planners and policymakers, the correct identification of physicians’ practice locations is critical, yet tremendous uncertainty endures in their use of existing national workforce data sets.…”

Use of Adult-Trained Medical Subspecialists by Children Seeking Medical Subspecialty Care

“…To classify providers, we linked National Provider Identifiers (NPI) in the claims to the National Plan and Provider Enumeration System (NPPES), 16 which associates each provider with one or more self-identified taxonomy codes representing provider type and specialty and has at least comparable accuracy to other national physician databases. 17 …”