Agreement of Medicare claims and tumor registry data for assessment of cancer-related treatment.

BACKGROUND: Although health claims data are increasingly used in evaluating variations in patterns of cancer care and outcomes, little is known about the comparability of these data with tumor registry information.
OBJECTIVES: To evaluate the agreement between Medicare claims and tumor registry data in measuring patterns of diagnostic and therapeutic procedures for older cancer patients. RESEARCH
DESIGN: Analysis of a database linking Surveillance, Epidemiology and End Results (SEER) registry data and Medicare claims in patients aged > or =65 years with cancer.
SUBJECTS: 361,255 Medicare patients with invasive breast, colorectal, endometrial, lung, pancreatic, and prostate cancer diagnosed between 1984 and 1993. MEASURES: Concordance of SEER files with corresponding Medicare claims.
RESULTS: Medicare claims generally identified patients who underwent resection and radical surgery according to SEER (ie, concordance > or =85%-90%) but less likely biopsy or local excision (ie, concordance < or =50%). In some instances, claims also categorized patients as having more invasive surgery than was listed in SEER and also provided incremental information about the use of surgical treatment after 4 months. SEER files and, to a lesser degree, Medicare claims identified radiation therapy not included in the other data source, and Medicare files also captured a significant number of patients with codes for chemotherapy.
CONCLUSIONS: Medicare files may be appropriate for studies of patterns of use of surgical treatment, but not for diagnostic procedures. The potential benefit of Medicare claims in identifying delayed surgical intervention and chemotherapy deserves further study.