Measuring clinically significant chemotherapy-related toxicities using Medicare claims from CALGB breast and lung cancer trial participants

Abstract

6595 Background: Because the elderly are numerically underrepresented in cancer clinical trials, the benefits and toxicities of cancer therapies in the general population of elderly patients is not known. Nevertheless, clinicians need such information. A solution may be found in analyses of observational data. Specific Aim: We performed a criterion validation study to determine the accuracy with which observational Medicare claims data measure clinically significant chemotherapy-related toxicities in elderly Medicare beneficiaries with cancer. Methods: We created a cohort of 175 elderly clinical trial patients treated on two Cancer and Leukemia Group B (CALGB) trials (i.e., 9,344 adjuvant breast and 9,730 advanced lung cancer trials) and merged participants’ CALGB data with their Centers for Medicare and Medicaid Services (CMS) data. From CALGB data, we identified all grade III/IV toxicities with a frequency of ≥3%. We reviewed diagnostic and procedure codes from CMS coding manuals, developed initial algorithms to measure the toxicities and then finalized the algorithms after empiric review of individual patients’ actual CMS codes incurred during the observation period (i.e., date of first trial treatment through 90 days following last trial treatment). We compared results of each of our CMS toxicity algorithms to gold-standard of CALGB grade III/IV toxicity information in order to calculate the CMS algorithms’ test characteristics. Results: The following 15 grade III /IV chemotherapy-related toxicities occurred in ≥3% of the 175 patients: white blood cell, hemoglobin, platelets, anorexia, nausea, vomiting, diarrhea, stomatitis, sensory neuropathy, motor neuropathy, motor or sensory neuropathy, dyspnea, hyperglycemia, infection, and malaise. Of these, only the CMS-based algorithm measuring ‘grade III/IV vomiting‘ had a sensitivity, specificity, and area under the ROC of ≥ 80%. Conclusions: The results of this preliminary study suggest that CMS claims data may be of only limited value in measuring clinically significant chemotherapy- related toxicities in elderly Medicare beneficiaries with cancer. Future research will focus on confirming these findings in a larger and more diverse patient sample. No significant financial relationships to disclose.