Factors Affecting Patient Adherence to Oral Anticancer Medications

Ami Vyas, PhD, MS, MBA, Department of Pharmacy Practice, College of Pharmacy, University of Rhode Island, Kingston, RI, determines the number of patients with cancer initiating oral anticancer therapy who were adherent to oral anticancer medications and identified predictors of adherence to oral anticancer medications such as out-of-pocket costs, hospitalization, and Medicare utilization.

Transcript                           

Hello everyone. My name is Dr Ami Vyas. I'm an associate professor of health outcomes research at University of Rhode Island, College of Pharmacy, in the Department of Pharmacy Practice.

So I'm here to present on a recent study that was published. The study is titled “Predictors of Adherence to Oral Anticancer Medications and Analysis of 2010–2018 US Nationwide Claims.” It was recently published in the Journal of Managed Care and Specialty Pharmacy in the August 2022 issue.

So a little bit more about my study. There has been a tremendous increase in the use of oral anticancer medications in the past few years. And this has caused a shift in the treatment paradigm, from patients receiving medications in hospitals and outpatient clinics, to patients been responsible for taking their own medications.

Now, adherence to oral anticancer medications is a big issue, with adherence ranging from 20% to 100%, depending on cancer types and several other factors. Now, it's very important that the patient adhere to their medications, as nonadherence to oral anticancer medications can result in poorer health outcomes including premature death. Various factors, including patient out-of-pocket costs, clinical and socio-demographic characteristics, and health system factors can influence adherence to oral anticancer medications. Recently, there has been a huge emphasis on examining social determinants of health that may affect patients access to medications.

Various studies that have examined patient adherence to oral anticancer medications used older data or focused on a specific cancer type. So we conducted a study to identify what proportion of patients were adherent to oral cancer medications and which factors affected patient adherence. We conducted our study across 10 different cancer types that included cancers of blood, brain, breast, colorectal, liver, lung, ovarian, prostate, renal, or stomach cancers. We selected these cancers because of their prevalence, high morbidity and mortality burden, and indications for oral anticancer medications.

For our study, we used 2010 through 2018, the identified Optum Clinformatics Data Mart commercial claims database. We identified patients initiating an oral anticancer medication between 2010 and 2017, which we called an index prescription date. We used indices to identify prescription of oral anticancer medications.

Medication adherence was measured during the 6-month period following the index prescription date and was it determined using the proportion of days covered, PDC (proportion of days covered) measure. If the PDC value was 0.8 or above, then the patient was considered adherent. Patient out-of-pocket costs during the 6-month period following the index prescription date were also determined. In addition to that, we also examined patient demographic characteristics that included age, sex, race and ethnicity, US region, while socioeconomic characteristics included census level, income level, education, and number of adults living in the household. In addition to these, we also examined health system factors that included insurance type and type of health plan. Clinical factors were also examined and these included cancer type, physical and psychiatric comorbidities. Some treatment-related factors were also examined; these included dosing schedule, typical dose, inpatient hospitalization, and use of additional anticancer treatments that are given intravenously or through infusion.

We determined the proportion of patients that were adherent to oral anticancer medications by their cancer type. And we also identified predictors of adherence to oral anticancer medications within each cancer type by performing multivariable logistic regressions.

Close to 38,000 patients were included in our study, out of which we found that 52% were adherent to oral cancer medications, while the rest, 48%, were not. Adherence we read by cancer type, with the highest adherence found in patients with stomach cancer and brain cancer, while the lowest of adherence was found in patients with ovarian cancer, colorectal cancer, or liver cancer.

In addition to this, we also found that average monthly out-of-pocket costs, were read by cancer type, with the highest out-of-pocket burden for patients with blood cancer or liver cancer.

Now, with regards to the predictors of medication adherence within each cancer type, we found that higher out-of-pocket costs were significantly associated with increased odds of nonadherence for all cancer types except for prostate cancer.

Additionally, we also found that patients who received concomitant injection chemotherapy were more likely to not adhere to their oral anticancer medications. They said ethnicity was also a significant predictor of oral anticancer medication nonadherence for some cancer types. For instance, among patients with blood cancer, those who were Black or Hispanic were more likely to not adhere to their medications compared to White patients. Sex was also a significant predictor of nonadherence for four out of seven cancer types, for which sex was assessed. All of this showed that men were more likely to be adherent than women.

With regards to health system factors, we found that those with renal cancer or stomach cancer who had Medicare low-income subsidy had higher odds of nonadherence compared to those with commercial insurance coverage.

So overall, we found that half of the patients with cancer were adherent to their oral anticancer medications after initiating the cancer therapy, which indicates that suboptimal adherence is a big issue.

Higher out-of-pocket cost was found to be significantly associated with nonadherence in many of these cancer patients. So patients with high cost sharing may not be able to afford the medication continually and may discontinue the treatment. Hence, it's very important to address the financial barriers and improve patient access to anticancer medications.

Additionally, patients with subsidized Medicare Part D plans were also more likely to be nonadherent. It's likely that these patients with low income subsidy may have fewer financial resources, which may impact their medication adherence.

Now, where a strategy is to reduce patient out-of-pocket costs and address of the barriers have been implemented, these include oral cancer drug price parity, provision low-income subsidy to Medicare cancer patients and, more broadly, closing the coverage cap of Medicare Part D. Our findings suggest that these strategies alone may not be sufficient to reduce patient out-of-pocket costs and improve their access to oral anticancer medications. Hence, other strategies, including capping annual patient out-of-pocket spending in the Medicare Part D design may be promising and helpful to these cancer patients.

Thank you.