Medicare Beneficiaries With Rectal Cancer in Regions With Lower Colorectal Surgeon Density Have Higher Rates of Abdominoperineal Resection: A Dartmouth Atlas Study
*Daniel Underbakke, *Ravinder Kang, *Srinivas Ivatury
Dartmouth Hitchcock Medical Center, Lebanon, NH
Objective. To evaluate the relationship between density of colorectal surgeons in a hospital referral region (HRR) and the rates of abdominoperineal resection (APR) or low anterior resection (LAR) for rectal cancer.
Design. Dartmouth Atlas study
Setting. 100% United States Medicare Part B claims data
Patients and other participants. 2014 Medicare beneficiaries with rectal cancer (ICD-9: 154.1). Using certification data from the American Board of Colon and Rectal Surgery, we determined the density of active board-certified colorectal surgeons in 2014 by HRR (low <5, medium 5-9, and high >9).
Interventions. APR (CPTs: 45110, 45395) or LAR (CPTs: 44145, 44146, 44207, 44298, 45112, 45397)
Main Outcome Measure. Rates of APR or LAR per Medicare Beneficiary (MB) compared to the density of colorectal surgeons in each HRR.
Results. 1,821 beneficiaries underwent APR, and 3,366 beneficiaries underwent LAR for rectal cancer in 2014. The national rates of APR and LAR were 6.66 and 12.12 per 100,000 MB, respectively. Individual rates were available for 46 HRRs for APR and 104 HRRs for LAR (those with >10 procedures/year). The average rates of APRs per 100,000 MB in the low, medium, and high density groups were 8.76, 7.82, and 6.66 respectively. The average rates of LARs per 100,000 in the low, medium, and high density groups were 13.07, 13.08, and 14.05 respectively.
Conclusions. Higher density of board-certified colorectal surgeons is associated with decreased rates of APR for Medicare beneficiaries. Higher colorectal surgeon density is associated with increased rates of LAR, albeit to an attenuated degree compared to APR.