Long-term efficacy of OROS® hydromorphone combined with pregabalin for chronic non-cancer neuropathic pain.

BACKGROUND AND OBJECTIVES: Treatment for chronic non-cancer neuropathic pain can be complicated by side effects and drug interactions. Combining opioid analgesics and calcium channel modulators may overcome these and improve efficacy. The objective of the present study was to evaluate the efficacy and safety of OROS® hydromorphone combined with pregabalin in patients with chronic non-cancer neuropathic pain. METHODS: This retrospective observational study was conducted on clinical records from patients aged ≥18 years with chronic non-cancer neuropathic [>4 on the Douleur Neuropathique en 4 questions (DN4) scale] pain of ≥6 months duration, with severe intensity [>4 on the Numerical Rating Scale (NRS); range 0-10], who attended all visits and had ≥12 months of follow-up at the Tor Vergata University Polyclinic Hospital, from November 2008 to February 2011. Patients received an oral combination of OROS® hydromorphone and pregabalin. Pain was evaluated at each visit (months 1, 3, 6, 9, and 12) using the NRS and DN4 scale; Patients' Global Impression of Change (PGIC) was administered at months 1, 6, and 12. Dosage and side effects were recorded at each visit. RESULTS: Of 1,292 patients (32 % men, mean ± SD age 67.6 ± 11.9 years), 1,126 attended all visits. Seventeen percent (n = 224) had purely neuropathic pain. Initial mean dosage was 6.06 ± 2.00 mg/day for OROS® hydromorphone, 113.02 ± 21.94 mg/day for pregabalin. Dosages increased up to month 6, and returned to near initial dosages at month 12 (range 4-120 mg/day for OROS® hydromorphone; 75-600 mg/day for pregabalin). NRS pain scores (mean ± standard deviation) were 7.25 ± 1.34 at baseline and 1.85 ± 1.36 at 12 months (p < 0.0001); DN4 scores were 6.19 ± 1.65 at baseline, reduced to 1.84 ± 1.25 at 12 months (p < 0.0001), reductions of 74.4 and 70.2 %, respectively. More than 90 % of patients had a ≥50 % score reduction on both scales after 12 months. The PGIC scale showed that >75 % of patients felt improvement at 1 month, increasing to 91 % and 93 % at 6 and 12 months. The incidence of side effects was similar between elderly (aged >65 years) and younger subjects; there were no cases of addiction. CONCLUSIONS: The OROS® hydromorphone and pregabalin combination was efficacious for chronic non-cancer neuropathic pain and well tolerated, providing significant pain reduction without the risk of addiction and with a good tolerability profile, regardless of age.