Abstract 2575: Adherence to oral oncolytics in patients with lung cancer
Authors: Hess Lisa M. , Louder Anthony , Winfree Katherine , Zhu Yajun E. , Oton Ana B. , Nair Radhika 
Published: July 2016

Abstract
Introduction
With the growth in availability of oral agents for cancer treatment, maintaining adherence is key to achieve positive patient outcomes (such as improved survival rates) and also may reduce healthcare costs. The objectives of this study were to examine oral oncolytic usage patterns among lung cancer patients and to understand the relationship with healthcare resource utilization (HCRU), costs, and survival.
Procedures
Medical and pharmacy data from Humana were used to identify members with lung cancer (ICD-9-CM 162.2-162.9) who initiated oral oncolytic therapy between 1/1/2008-6/30/2013 without prior oral chemotherapy use. The study was focused on erlotinib due to infrequent use of other oral agents. Medication adherence (medication possession ratio - MPR) and persistence (time to discontinuation based on a 60 day gap in therapy) were evaluated across lines of therapy. Demographic and clinical characteristics and erlotinib usage of the study population were summarized descriptively. Generalized linear models were used to examine the association between erlotinib use and healthcare cost and utilization. Cox regression models were used to evaluate the association between erlotinib use and survival. In all the models adherence and persistence were grouped into quintiles.
Results
The 1452 members meeting eligibility criteria had a mean age of 71.9 (±9.1) years, were 45.9% male, and 88.9% were insured by Medicare; 62% received intravenous chemotherapy before initiating erlotinib. Nonadherence (MPR &lt; 80%) was identified in 12.5% of members with ≥2 claims (n = 1088). The highest adherence quintile was associated with both higher total healthcare costs ($5218 vs. $4028 per month; p&lt;0.0001) and total pharmacy costs ($2618 vs. $1915 per month; p&lt;0.0001) compared to lowest adherence quintile. Overall, the average duration of treatment was 204 (± 256) days. The highest persistence quintile was associated with fewer outpatient visits (2.9 vs. 3.6 per month; p = 0.0126), inpatient stays (0.31 vs. 0.07 per month; p&lt;0.0001) and emergency room visits (0.14 vs. 0.02 per month; p = 0.0086), than the lowest persistence quintile. Persistence, but not adherence, was associated with improved survival outcomes [persistence quintiles 4 and 5 vs quintile 1, adjusted hazard ratio (adjHR) 0.21 and 0.51, respectively, p&lt;0.0001; MPR quintiles 4 and 5 vs quintile 1, adjHR 1.73 and 1.94, respectively, p&lt;0.0001].
Conclusions
Adherence to erlotinib was high in lung cancer, limiting detailed investigation into factors associated with reduced adherence. This study is limited in that all conclusions are based on the observed population without making any bias adjustment. We hypothesized that improved adherence would be associated with improved survival and reduced costs; this was not found to be the case. Those who remained on oral oncolytics for a longer period of time had a greater survival regardless of line of therapy.
Citation Format: Lisa M. Hess, Anthony Louder, Katherine Winfree, Yajun E. Zhu, Ana B. Oton, Radhika Nair. Adherence to oral oncolytics in patients with lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2575.