Relationship Between Adherence to Opioid Analgesics and Pain Beliefs Among Patients with Cancer Pain at Tertiary Care Hospitals in Malaysia

CONTEXT: Pain is a common and distressing symptom among cancer patients. Opioid analgesics are the mainstay of cancer pain management, and adequate adherence plays an important role in achieving good pain control. PURPOSE: To determine the level of adherence to opioid analgesics in patients with cancer pain and to identify factors that may influence the adherence. PATIENT AND METHODS: This was a cross-sectional study conducted from March to June 2018 at two tertiary care hospitals in Malaysia. Study instruments consisted of a set of validated questionnaires; the Medication Compliance Questionnaire, Brief Pain Inventory and Pain Opioid Analgesic Beliefs─Cancer scale. RESULTS: A total of 134 patients participated in this study. The patients’ adherence scores ranged from 52–100%. Factors with a moderate, statistically significant negative correlation with adherence were negative effect beliefs (r(s)= −0.53, p<0.001), pain endurance beliefs (r(s) = −0.49, p<0.001) and the use of aqueous morphine (r(s) = −0.26, p=0.002). A multiple linear regression model on these predictors resulted in a final model which accounted for 47.0% of the total variance in adherence (R(2) = 0.47, F (7, 126) = 15.75, p<0.001). After controlling for other variables, negative effect beliefs were the strongest contributor to the model (β = −0.39, p<0.001) and uniquely explained 12.3% of the total variance. CONCLUSION: The overall adherence to opioid analgesics among Malaysian patients with cancer pain was good. Negative effects beliefs regarding cancer pain and opioids strongly predicted adherence.