Risk of Constipation in Patients Prescribed Fentanyl Transdermal System or Oxycodone Hydrochloride Controlled-Release in a California Medicaid Population

Objective: To compare the risk of developing constipation between patients prescribed fentanyl transdermal system or oxycodone hydrochloride (HCl) controlled-release. Design: California Medicaid (Medi-Cal) claims data. Setting: Medicaid beneficiaries in California. Participants: Chronic pain patients who received a prescription for transdermal fentanyl or oxycodone controlled-release between October 1, 1997, and February 28, 2000, for at least three consecutive months. Main Outcome Measures: Constipation was defined using the International Classification of Diseases, Ninth Revision, Clinical Modification code (ICD-9-CM 564.0). The association between long-acting opioid use and constipation was determined by multivariate logistic regression after controlling for drug strength, short-acting opioid usage, and comorbidities. Odds ratios (ORs), 95% confidence intervals (CIs), and P values were reported. Results: A total of 2,095 patients were included in the regression analysis (transdermal fentanyl = 877; oxycodone controlled-release = 1,218). Seventy-five patients received a constipation diagnosis (transdermal fentanyl = 28; oxycodone controlled-release = 47). Approximately 40% of patients were at least 65 years of age. Overall, oxycodone controlled-release patients had a significantly greater risk of developing constipation compared with transdermal fentanyl patients (transdermal fentanyl: n = 877; oxycodone controlled-release: n = 1,218; OR = 2.55; 95% CI = 1.33-4.89; P = 0.005). Among patients who were 65 years or older, oxycodone controlled-release patients were 7.33 times more likely to be constipated than transdermal fentanyl patients (transdermal fentanyl: n = 518; oxycodone controlled-release: n = 317; OR = 7.33; 95% CI = 1.98-27.13; P = 0.003). Conclusion: These findings suggest that patients prescribed transdermal fentanyl may have a significantly lower risk of developing constipation compared with oxycodone controlled-release, particularly in the elderly.