Accuracy and completeness of medicare claims data for surgical treatment of breast cancer

BACKGROUND. Although a number of studies have used Medicare claims data to study trends and variations in breast cancer treatment, the accuracy and co mpleteness of information on surgical treatment for breast cancer in the Me dicare data have not been validated. OBJECTIVES. This study assessed the accuracy and completeness of Medicare c laims data for breast cancer surgery to determine whether Medicare claims c an serve as a source of data to augment information collected by cancer reg istries. METHODS. We used the Surveillance, Epidemiology and End Results (SEER) Canc er Registry-Medicare data and compared Medicare claims on surgery with the surgery recorded by the SEER registries for 23,709 women diagnosed with bre ast cancer at greater than or equal to 65 years of age from 1991 through 19 93. RESULTS. More than 95% of women having mastectomies according to the Medica re data were confirmed by SEER. For breast-conserving surgery, 91% of cases were confirmed by SEER. The Medicare physician services claims and inpatie nt claims were approximately equal in accuracy on type of surgery. The Medi care outpatient claims were less accurate for breast-conserving surgery. In terms of completeness, when the 3 claims sources were combined, 94% of pat ients receiving breast cancer surgery according to SEER were identified by Medicare. CONCLUSIONS. The combined Medicare claims database, which includes the inpa tient, outpatient, and physician service claims, provides valid information on surgical treatment among women known to have breast cancer. The claims are a rich source of data to augment the information collected by tumor reg istries and provide information that can be used to follow long-term outcom es of Medicare beneficiaries.