Should Measures of Health Care Availability Be Based on the Providers or the Procedures? A Case Study with...

Patients with colorectal cancer (CRC) living in rural areas have lower survival rates than those in urban areas, potentially because of lack of access to quality CRC screening and treatment. The purpose of this study was to compare traditional physician density (ie, colonoscopy provider availability per capita) against a new physician density measure using an example case of colonoscopy volume and quality. The latter is particularly relevant for rural providers, who may have fewer patients and are more frequently nongastroenterologists.

We conducted a secondary data analysis of the 2014 Medicare Provider Utilization and Payment Database and the National Cancer Institute State Cancer Profile Database. Volume-weighted physician density scores at the state and county levels were created, accounting for (1) the physician's annual colonoscopy volume and (2) whether the physician performs ≥100 procedures per year. We compared volume-weighted versus traditional density, overall and by rurality, and examined their correlation with CRC screening, incidence, and mortality rates.

The difference between volume-weighted and traditional density scores was particularly large in rural parts of the West and Midwest, and it was most similar in the Northeast. Although weak, correlations with CRC outcomes were stronger for volume-weighted density, and they did not differ by rurality.

Our new method is an improvement over traditional methods because it considers the variation of physician procedure volume, and it has a stronger correlation with population health outcomes. Weighted density scores portray a more realistic picture of physician supply, particularly in rural areas.