Study finds high out-of-pocket costs remain a barrier for initiation of oral cancer drugs.
High cost sharing under Medicare Part D was associated with reduced and delayed initiation of oral tyrosine kinase inhibitors (TKIs) for the treatment of chronic myeloid leukemia (CML) in a recent study.
The study, published in The American Journal of Managed Care, was a retrospective claims-based analysis that collected data from the Medicare Chronic Condition Data Warehouse files.
Specific data on Medicare inpatient (Part A), outpatient (Part B), and prescription drug (Part D) data files linked with beneficiary summary files were extracted, as well as Part D prescription drug plan characteristics files among patients who had at least one diagnosis of CML.
Researchers compared TKI initiation rates and time to initiation between fee-for-service non-LIS Part D patients newly diagnosed with CML, along with patients who qualify for full low-income subsidies (LIS) with nominal cost sharing of ≤$5.
Through the main sample selection criteria, researchers identified 1053 patients with newly diagnosed CML between 2011 and 2013.
The non-LIS group was found to be older and had a higher percentage of white and male patients compared with the LIS group. They also had a lower mean Charlson comorbidity score, but had a larger proportion of patients with moderate-to-severe CML at diagnosis.
Furthermore, the non-LIS group also had a greater percentage of patients faced with prior authorization requirements for TKIs, compared with the LIS group. Regardless of whether or not non-LIS patient insurance plans had a distinct specialty tier, all were subject to 25% to 33% coinsurance for TKIs during the initial coverage phase.
The first 30-day TKI prescription drug fill straddled the Part D benefit phases, which pushed beneficiaries from the initial coverage phase to the coverage gap phase, and generated a mean out-of-pocket cost of approximately $2600 or more for non-LIS patients. Full LIS patients had out-of-pocket costs of $5 or less for their initial TKI fill.
For TKI initiation, the Kaplan-Meier curves were stratified by LIS status. The study found that the time to TKI initiation was significantly longer in the non-LIS group compared with the LIS group (log-rank P <.001).
There was a significantly lower proportion of individuals in the non-LIS group who initiated a TKI within 1 month (21%) and 3 months (36%) of initial CML diagnosis compared with the LIS group (53% and 65%, respectively). Furthermore, 6 months after the first CML claim, the non-LIS group was still less likely than LIS patients to initiate a TKI (45.3% vs 66.9%; P <.001).
For non-LIS patients initiating a TKI, it took them twice as long to get the prescription filled (mean = 50.9 vs 23.7 days; P <.001). The findings were confirmed after adjusting for sociodemographic, clinical, and plan characteristics in the Cox regression analysis (hazard ratio, 0.59; 95% CI, 0.45-0.76).
Additionally, extensive sensitivity analyses that used various outcome definitions, analytic techniques, and sample selection criteria confirmed that the findings were consistent with the main results.
Limitations to the study included it being a cross-sectional analysis that used LIS patients as a control group, which prevented them from establishing causal relationships between high cost sharing and treatment initiation; the potential for unobserved cofounding; the data set might not have captured patients who received medication outside of their Part D benefit, meaning some patients who were classified as not initiating treatment or delaying it may have received medication through other means, therefore it would not be recorded in Medicare Part D prescription claims; and the study researchers required the sample be diagnosed during Medicare Part D’s initial coverage period.
The study’s findings suggest that out-of-pocket costs may limit and delay the initiation of TKIs in newly diagnosed CML patients, and that policy changes are needed to ensure optimal access to specialty medications under Medicare Part D, the study concluded.