External Validation of a Claims-Based Algorithm for Classifying Kidney-Cancer Surgeries

Published In: BMC Health Services Research, v. 9, June 6, 2009, p. 1-7

Posted on RAND.org on January 01, 2009

by David C. Miller, Christopher S. Saigal, Joan L. Warren, Meryl Leventhal, Dennis Deapen, Mousumi Banerjee, Julie Lai, Janet M. Hanley, Mark Litwin

BACKGROUND: Unlike other malignancies, there is no literature supporting the accuracy of medical claims data for identifying surgical treatments among patients with kidney cancer. The authors sought to validate externally a previously published Medicare-claims-based algorithm for classifying surgical treatments among patients with early-stage kidney cancer. To achieve this aim, they compared procedure assignments based on Medicare claims with the type of surgery specified in SEER registry data and clinical operative reports. METHODS: Using linked SEER-Medicare data, the authors calculated the agreement between Medicare claims and SEER data for identification of cancer-directed surgery among 6,515 patients diagnosed with early-stage kidney cancer. Next, for a subset of 120 cases, they determined the agreement between the claims algorithm and the medical record. Finally, using the medical record as the reference-standard, the authors calculated the sensitivity, specificity, and positive and negative predictive values of the claims algorithm. RESULTS: Among 6,515 cases, Medicare claims and SEER data identified 5,483 (84.1%) and 5,774 (88.6%) patients, respectively, who underwent cancer-directed surgery (observed agreement = 93%, kappa = 0.69, 95% CI 0.66 - 0.71). The two data sources demonstrated 97% agreement for classification of partial versus radical nephrectomy (kappa = 0.83, 95% CI 0.81 - 0.86). The authors observed 97% agreement between the claims algorithm and clinical operative reports; the positive predictive value of the claims algorithm exceeded 90% for identification of both partial nephrectomy and laparoscopic surgery. CONCLUSION: Medicare claims represent an accurate data source for ascertainment of population-based patterns of surgical care among patients with early-stage kidney cancer.

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