Change in opioid use after the initiation of gabapentin therapy in patients with postherpetic neuralgia.

BACKGROUND: Postherpetic neuralgia (PHN) is a chronic painful disorder that sometimes develops after an acute episode of herpes zoster infection (shingles) and can be difficult to treat. Although opioids are sometimes effective for chronic neuropathic pain, adverse effects are common, particularly among the elderly, and may cause many patients to discontinue therapy.

OBJECTIVE: This study examined changes in opioid use after the initiation of gabapentin therapy in patients with PHN.

METHODS: A health insurance claims database was used to identify all persons aged >or= 18 years who began therapy with gabapentin in 2000 or 2001 and had either (1) >or=2 medical claims with a diagnosis of PHN during the 6-month period before the first receipt of gabapentin (index date) or (2) 1 such claim <or=14 days before the index date. Persons who were not continuously eligible for medical and drug benefits for 6 months before and after the index date (pretreatment and follow-up, respectively) were dropped from the study sample. Use of opioids, including both short- and long-acting formulations, was compared between pretreatment and follow-up. Patients were stratified in the study analyses by whether they received 1 or >or=2 prescriptions for gabapentin.

RESULTS: Forty-five patients with PHN began therapy with gabapentin during the period of interest; 35 (77.8%) received >or=2 prescriptions for gabapentin. The proportion of patients receiving opioids decreased significantly between pretreatment and follow-up (from 88.9% to 71.1%; P = 0.03); the mean number of opioid prescriptions per patient also decreased significantly (from 3.9 to 3.0; P = 0.03). These reductions were observed only in patients who received >or=2 prescriptions for gabapentin; there was no significant change in opioid use among those who received only 1 prescription for gabapentin.

CONCLUSION: In this study, initiation of gabapentin therapy in patients with PHN was associated with a reduction in the use of opioid analgesics.