Side Effects, Self-Management Activities, and Adherence to Oral Anticancer Agents

Purpose: There are growing concerns about patients' adherence to oral anticancer agents (OAAs), and the need for patients to engage in self-management of OAA-related side effects. We assessed associations among adherence, severity of side effects, and effectiveness of self-management of side effects in patients taking capecitabine. Methods: Adherence to capecitabine at 6 weeks was measured by the Medication Event Monitoring System among 50 patients with gastrointestinal cancers. Severity of side effects related to capecitabine and effectiveness of self-management of side effects were captured using the Modified Self-Care Diary at the time of enrollment and weekly for 6 weeks. Spearman's correlation, Mann-Whitney U-tests, and multiple linear regression were conducted, p<0.05. Results: Overall mean adherence rate was 85.4 +/- 14.1%. Adherence rate was not significantly correlated to the mean severity of total side effects at any time point and was correlated with the mean effectiveness of self-management of total side effects only at week 2 (rho=0.29, p=0.04). However, adherence rate was associated with the mean severity of one specific side effect, diarrhea, at 6 weeks (rho=0.36, p=0.01) and marginally correlated to the mean effectiveness of self-management of diarrhea at 6 weeks (rho=0.28, p=0.05). Mean severity of diarrhea at 6 weeks was an independent predictor of adherence rate (b=4.97, p=0.01), with the control of age (b=0.52, p=0.002), number of outpatient medications (b=1.12, p=0.007), health literacy (b=2.53, p=0.04), diagnosis of colorectal cancer (b=11.6, p=0.03), and capecitabine in combination with other chemotherapies (b=16.8, p=0.001) in the model. Conclusion: This pilot study suggests ongoing examination of both severity and effectiveness of self-management of side effects in future studies of adherence to OAAs is merited. There is a need for future studies with larger sample sizes that explore the complex relationships among adherence, severity of side effects, and effectiveness of self-management of side effects in OAA therapy.