Costs associated with adverse events in patients with metastatic renal cell carcinoma

To estimate adverse event (AE) costs in patients receiving targeted therapies for the first line treatment of metastatic renal cell carcinoma (mRCC).

Retrospective study based on healthcare claims data for patients with mRCC, aged ≥18 years, receiving first-line treatment with targeted therapies. AEs of interest comprised of abdominal pain, back pain, diarrhea, dyspnea, extremity pain, fatigue/asthenia, hand-foot syndrome, hypertension, lymphopenia, nausea/vomiting, neutropenia, proteinuria, and thrombocytopenia. Healthcare encounters for AEs were based on ICD-9-CM diagnosis/procedure codes on healthcare claims. AE costs were examined over a 30-day period, beginning with the date of first mention of AE, and were estimated based on the difference in total costs between patients with and without events. Drug costs of targeted agents were excluded from the analysis. Multivariate generalized linear models with a log-link function and gamma response probability distribution were utilized to control for differences in baseline characteristics between patients with and without evidence of AEs.

A total of 533 patients were included in this analysis: 418 patients with AE and 115 patients without AE. Baseline characteristics were generally similar between patients in the two groups. The GLM-based estimate of incremental 30-day post-event costs among patients with evidence of any adverse events was $9807 (95% CI = $4386-$22,947). For all types of adverse events examined, the estimated difference in costs between evented and non-evented patients was positive; the 95% CI did not include zero for all of the adverse events considered, except hypertension and proteinurea. Study limitations include errors of commission/omission, especially as they may affect case-finding methods that rely on ICD-9-CM diagnosis and procedure codes, as was the case in the current study.

Costs associated with AEs of first-line targeted therapies are substantial in patients with mRCC. Efforts to prevent and/or better manage these events may reduce overall healthcare costs.