Primary care utilization and colorectal cancer incidence and mortality among Medicare beneficiaries: a population-based, case-control study.

Background: Utilization of primary care may decrease colorectal cancer (CRC) incidence and death through greater receipt of CRC screening tests.

Objective: To examine the association of primary care utilization with CRC incidence, CRC deaths, and all-cause mortality.

Design: Population-based, case-control study.

Setting: Medicare program.

Participants: Persons aged 67 to 85 years diagnosed with CRC between 1994 and 2005 in U.S. Surveillance, Epidemiology, and End Results (SEER) regions matched with control patients (n = 205,804 for CRC incidence, 54,160 for CRC mortality, and 121,070 for all-cause mortality).

Measurements: Primary care visits in the 4- to 27-month period before CRC diagnosis, CRC incidence, CRC mortality, and all-cause mortality.

Results: Compared with persons having 0 or 1 primary care visit, persons with 5 to 10 visits had lower CRC incidence (adjusted odds ratio [OR], 0.94 [95% CI, 0.91 to 0.96]) and mortality (adjusted OR, 0.78 [CI, 0.75 to 0.82]) and lower all-cause mortality (adjusted OR, 0.79 [CI, 0.76 to 0.82]). Associations were stronger in patients with late-stage CRC diagnosis, distal lesions, and diagnosis in more recent years when there was greater Medicare screening coverage. Ever receipt of CRC screening and polypectomy mediated the association of primary care utilization with CRC incidence.

Limitation: This study used administrative data, which made it difficult to identify potential confounders and prevented examination of the content of primary care visits.

Conclusion: Medicare beneficiaries with higher utilization of primary care have lower CRC incidence and mortality and lower overall mortality. Increasing and promoting access to primary care in the United States for Medicare beneficiaries may help decrease the national burden of CRC.

Primary Funding Source: American Cancer Society.