Geographic and patient variation among medicare beneficiaries in the use of follow-up testing after surgery for nonmetastatic colorectal carcinoma

BACKGROUND. There are a paucity of data supporting the routine use of follow-up testing to detect recurrent disease after potentially curative initial surgery in patients with nonmetastatic colorectal carcinoma. METHODS. Using the population-based Surveillance, Epidemiology, and End Results (SEER) registry, all patients age greater than or equal to 65 years with local or regional colorectal carcinoma who were diagnosed in 1991, underwent surgical resection, and survived at least 6 months after diagnosis were identified. All inpatient, hospital outpatient, and physician/supplier Medicare claims from 6 months after diagnosis through 1994 were examined for follow-up procedures of interest. procedure use during follow-up was compared across patient groups using both bivariate and multivariate analyses. RESULTS. A total of 5716 patients were identified, with 1.3% found to have developed subsequent primary tumors of the colon or rectum, and 74% surviving through 1994. One or more procedures of interest were performed in 88% of patients; the most commonly performed tests were liver enzymes, chest X-rays, colonoscopy, and computed tomography scans. Lower rates of testing generally were observed with older age groups, patients with fewer comorbidities, and patients who did not survive through the follow-up period. Among all procedures studied, there also was significant variation in the rates of testing across the 9 SEER areas, varying from 1.5-fold to 3.6-fold. The geographic variation persisted in multivariate models adjusting for potentially confounding factors. CONCLUSIONS. The current study found significant variability in the use of follow-up procedures, with the most striking differences apparent across geographic regions. Further studies are needed to determine the underlying reasons for the disparities, as well as the impact of surveillance on patient outcomes. Cancer 1999; 85:2124-31. (C) 1999 American Cancer Society.