Comparative effectiveness and safety of thalidomide and lenalidomide in patients with multiple myeloma in the United States of America: A population-based cohort study.

BACKGROUND: The comparative effectiveness of thalidomide and lenalidomide in the treatment of multiple myeloma has not been established. We conducted an observational cohort study of multiple myeloma patients receiving either thalidomide or lenalidomide in routine care in the United States of America to assess their comparative survival and rates of peripheral neuropathy.

METHODS: Myeloma patients were identified and followed using administrative claims data from a large national health insurance provider (UnitedHealth). Patients were eligible if they initiated treatment with either lenalidomide or thalidomide between 2004 and 2013. Propensity score stratified Cox proportional hazards regression was used to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for death and new-onset peripheral neuropathy (defined by International Classification of Disease, Ninth Revision codes or a new prescription intended to treat neuropathic pain).

FINDINGS: Our cohort included 1264 myeloma patients who initiated either thalidomide or lenalidomide. Among 406 new users of thalidomide, 142 (35%) developed peripheral neuropathy during a mean 499 person-days of follow-up. Among 858 new users of lenalidomide, 244 (29%) developed neuropathy during 587 person-days. Compared with thalidomide initiators, lenalidomide initiators had a reduced risk of peripheral neuropathy (HR 0.71, 95% CI: 0.56-0.92). We found no difference in rates of death (HR 1.00, 95% CI: 0.71-1.41).

INTERPRETATION: Our results agree with the findings of recently published trials suggesting that thalidomide and lenalidomide are equivalent with respect to survival outcomes but different with respect to neurotoxicity in clinical practice settings.