Sensitivity of Medicare claims data for measuring use of standard multiagent chemotherapy regimens.

PURPOSE: We sought to determine the accuracy with which Medicare billing data documents elderly Medicare cancer patients' receipt of common multiagent chemotherapy regimens.
METHODS: We merged gold-standard clinical trial data from 406 elderly cancer patients known to be treated on 1 of 6 Cancer and Leukemia Group B (CALGB) breast, colorectal, and lung cancer trials (trial numbers; 9344, 9730, 9235,9732, 80203, 89803) with their Medicare claims data from Centers for Medicare and Medicaid Services (CMS). Comparing CMS chemotherapy codes to gold-standard CALGB treatment data, we estimated Medicare data's sensitivity at measuring the correct drugs and schedule for each of the multiagent chemotherapy regimens.
RESULTS: Overall 92% (375/406) of CALGB patients had contemporaneous CMS claims indicating receipt of chemotherapy. The overall sensitivity of CMS ambulatory claims for documenting treatment with the correct drugs and on the correct schedule (ie, all drugs had to be billed on the same day) for the 5 common multiagent chemotherapy regimens was 78% (275/354) for those potentially treated in the ambulatory setting. The sensitivity was similar for all treatment regimens: carboplatin and paclitaxel 83%, 5-fluorouracil and leucovorin 80%, fluorouracil, leucovorin, and irinotecan (FOLFIRI) 76%, doxorubicin and cyclophosphamide 75%, and cisplatin and etoposide 75%.
CONCLUSIONS: We correctly identified at least 3-quarters of elderly Medicare cancer patients treated on a clinical trial with standard first-line multiagent chemotherapy regimens in the ambulatory setting by applying coding algorithms to their CMS claims. The algorithms may be useful in identifying cohorts of elderly Medicare patients for observational studies of the comparative effectiveness of standard multiagent chemotherapy regimens.