Adherence to Analgesic Drugs and its Associated Factors among Patients with Cancer Pain: A Cross- sectional Study in China

Objectives: Pain is one of the most common and distressing symptoms co-occurring with cancer progression and treatment, and medication adherence plays an important role in achieving good pain control. However, research on medication adherence and influential factors among individuals with cancer pain (CP) is limited in China. The present study aimed to investigate the adherence to analgesics in patients with CP in China and to identify factors that may influence adherence. Methods: A cross-sectional study was conducted from June 2020 to February 2021. Study instruments consisted of a set of validated questionnaires, 5 measurement instruments including the numerical rating scale (NRS), ID-Pain, Morisky Medication Adherence Scale-Chinese validated version (MMAS-C), Beliefs about Medicines Questionnaire (BMQ) - Specific, and the Hospital Anxiety and Depression Scale (HADS). Results: A total of 141 participants with CP including 71 males (50.4%), aged 54.5 +/- 15.5 years were surveyed in this study. Overall, 83 patients (58.9%) showed adherence, but 58 patients (41.1%) showed non-adherence to analgesics. The univariate analysis showed that analgesic adherence was associated with pain duration of>3 months, outbreaks of pain in the last 24 hours, presence of side effects, getting analgesics in time, presence of neuropathic pain, stopping analgesics or adjusting dosage by themselves, presence of anxiety and depression, and beliefs about medicines. Moreover, the multivariate logistic regression showed that getting analgesic drugs in time (odds ratio [OR]=5.218, 95% confidence interval [CI] 1.691-16.100) and high BMQ-Necessity (OR=1.907, 95% CI 1.418-2.565) were associated with high adherence, stopping analgesics or adjusting dosage by themselves (OR=7.958, 95% CI 2.443-25.926) and high BMQ-Concern (OR=0.760, 95% CI 0.600-0.964) were more likely to be associated with non-adherence. Conclusion: In view of our findings, it may be critical for individuals to have a better understanding and strong beliefs about their prescribed analgesic drugs. Pain education, counseling and follow-up of patients and their caregivers, and removal of barriers to accessing analgesic drugs could be considered in further intervention strategies.