One of the most common orally administered antimyeloma agents, lenalidomide, has significantly improved outcomes in multiple myeloma, including in older patients. However, despite its utilization and cost, the rates and factors related to adherence to lenalidomide in older adults with newly diagnosed multiple myeloma remain unknown.

Data were collected from adults with newly diagnosed multiple myeloma over age 65 years being treated with lenalidomide therapy between the years 2007 and 2014 in the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked databases. Adherence was measured as medication possession ratio (MPR), which was defined as the ratio of the number of days the patient had pills in their possession to the number of days in the observation period in the first year after myeloma diagnosis. MPR of < 90% was considered poor adherence.

A total of 793 patients were included in the analysis. The mean MPR in our cohort was 89.5 ± 9.3%. Overall, 38% (n = 302) of the patients were considered to have poor adherence. Factors associated with poor adherence included increasing age (adjusted odds ratio [aOR] = 1.03 per year; 95% confidence interval [CI], 1.00-1.05; P = .024), black race (aOR = 1.72; 95% CI, 1.08-2.73; P = .022), and polypharmacy (aOR = 1.04 per medication; 95% CI, 1.01-1.08; P = .008).

Over a third of older adults with newly diagnosed multiple myeloma were considered to have poor adherence to lenalidomide, using the MPR as a surrogate for adherence. This highlights the need to further understand factors and devise strategies to support adherence in this patient cohort.