Factors affecting acceptability of titrated oxymorphone extended release in chronic low back pain - an individual patient analysis.

Objective: To evaluate the influence of age, sex, and previous opioid experience on the likelihood of successfully titrating opioid-naive and experienced patients with chronic low back pain (CLBP) to an effective and well-tolerated dose of oxymorphone extended release (ER).

Methods: Post hoc analysis of open-label titration phases of two enriched-enrollment randomized-withdrawal phase III trials in 575 adults with moderate-to-severe CLBP. Opioid-naive patients (n = 325) initiated oxymorphone ER at 10 mg/day (5 mg q12 h). Opioid-experienced patients (n = 250) initiated at a dose equianalgesic to their previous opioid and were allowed doses of 5 mg oxymorphone immediate-release rescue medication every 4-6 h, as needed. Oxymorphone ER was gradually titrated to a dose that reduced pain to
Clinical Trial Registration: NCT00225797, NCT00226421.

Main Outcome Measures: Number of patients reaching stabilized oxymorphone ER dose, reasons for treatment discontinuation in patients not reaching stabilized dose.

Results: Open-label titration was successful in 61% (348/575) of patients, and similar proportions of men (63%) and women (59%) and opioid-naive (63%) and experienced (57%) patients. Patients aged >or=65 years were less likely than patients aged <65 years to complete titration (45 vs. 63%; p = 0.002; 95% CI, -0.30 to -0.06) and more likely to discontinue owing to adverse events (40 vs. 15%; p < 0.001; 95% CI, 0.14-0.36). Oxycodone-experienced patients were less likely than hydrocodone-experienced patients to complete titration (46 vs. 62%, p = 0.03; 95% CI,-0.30 to -0.02). Among successfully titrated patients, pain decreased regardless of prior opioid therapy, sex, or age.

Conclusions: Most patients with CLBP were titrated to an effective, generally well-tolerated oxymorphone ER dose. Older patients and those converted from oxycodone may require more gradual titration. A study limitation is that patients initiated oxymorphone ER to comply with protocol, whereas treatment failure typically motivates opioid initiation or switching in clinical practice.