Background: Medication can help improve disease progression and survival. One way to improve adherence is to facilitate ease of administration, ie, oral vs IV. Our study of veterans with hepatocellular cancer (HCC) on sorafenib therapy aimed to assess the factors that affect adherence and overall survival.
Methods: A retrospective analysis of national level data from 2007 to 2013 collected by 120 VA medical centers across the country on diagnosing and treating patients with cancer was used for the study. Data on age at diagnosis, gender, race, marital status, comorbidities, concurrent medication use, days from diagnosis to treatment, days medication was supplied for, and medication refills were obtained. Sorafenib adherence was calculated from the medication supply and refill information. Survival till time of death or endpoint was also calculated. Data were analyzed through descriptive analysis, chi-square tests, t tests, Pearson correlations, and regression analysis to assess factors related to adherence and survival as well as differences in adherence and survival.
Results: In our study, about 2,778 were prescribed sorafenib. Most veterans were males (99%) with a mean age of 62 years. Of these, 2,006 (72%) were adherent to the treatment in some way. Adherence was associated significantly with ethnicity (P < .001). Those adherent to their therapy were older at time of diagnosis compared with those who were not ad-herent (62.4 years vs 61.4 years, t = 3.041, P < .01). There were no significant associations with marital status, gen-der, or presence of comorbidities. Increased adherence per-centage was negatively related to cost of treatment (r = -0.14, P < .001) and negatively related to overall survival (r = -0.353, P < .001). The number of concurrent medications (odds ratio [OR] 0.969, 95% confidence interval [CI] = 0.95-0.99, P < .01) and total number of treatment days (OR 0.997, 95% CI = 0.997-0.998, P < .001) were significantly related to chemotherapy adherence. In regression analysis, overall survival was also related to total treatment days (r2 = 0.503, P < .001).
Implications: Understanding and targeting factors that affect chemotherapy adherence and total treatment days can affect disease outcomes, including survival.
