Impact of a Clinical Pharmacy Consult Service on Guideline Adherence and Management of Gabapentin for Neuropathic Pain

OBJECTIVES: Our objectives were to (1) determine whether a computerized clinical pharmacy approval and follow-up consult process for ordering new prescriptions for gabapentin for the treatment of neuropathic pain decreased the number of patients without documented treatment benefit while increasing follow-up and documentation of effectiveness, and (2) describe gabapentin use patterns at a Veterans Affairs (VA) Medical Center, including the use of first-line therapies prior to gabapentin therapy for neuropathic pain. METHODS: The clinical pharmacy intervention included review of (1) the indication for gabapentin; (2) the required use and failure or contraindication of 3 first-line therapies: nonsteroidal anti-inflammatory drugs (NSAIDs), tricyclic anti-depressants (TCAs), and capsaicin cream; (3) the initial pain assessment; and (4) patient follow-up in 4 to 6 weeks, with repeat pain assessment. A retrospective chart review was performed for all patients who received a new prescription for gabapentin from October 2002 to April 2003 at the Portland VA Medical Center (PVAMC). The outcomes of interest for the provider group versus the clinical pharmacy managed group included follow-up at 6 weeks or less versus follow-up at more than 6 weeks, documentation of treatment benefit, how many of the 3 first-line therapies were tried before gabapentin, and whether the gabapentin therapy was discontinued. RESULTS: There were 237 patients who received a new prescription for gabapentin between October 2002 and April 2003. Of these gabapentin prescriptions, 61% (n=144) were prescribed for neuropathic pain. Of the new gabapentin prescriptions for neuropathic pain, 61% (n=88) were made from approved clinical pharmacy consults, 38% (n=54) were ordered without a clinical pharmacy consult, and 1% (n=2) were not included because the patient received the drug despite denial by the clinical pharmacy consult. The rate of follow-up to assess documentation of benefit of therapy with gabapentin was 87% (n=62) in the clinical pharmacy consult group compared with 51% (n=27) in the provider-managed group (c2=18.07, Pless than0.001). Of the patients who were assessed by follow-up, 89% (n=55) of the clinical pharmacy consult group received follow-up within 6 weeks versus 52% (n=14) of the provider-managed group (c2=12.63, P less than0.001). Compared with the patients managed by clinical pharmacists, 43% (n=23) of the gabapentin patients in the provider-managed group had no evidence of prior use of any of the 3 agents required by the gabapentin neuropathic pain guideline, 55% (n=29) had evidence of prior use of 1 or 2 first-line agents, and only 2% (n=1) had evidence of prior use of all 3 required first-line agents, versus 100% (n=71) of the patients managed by clinical pharmacy consult. There was no difference in the rate of continuation of gabapentin therapy in the group of patients who received clinical pharmacy consults (65%) compared with the provider-managed group (68%, c2=0.11, P=0.718). Of the 148 pharmacy consults for new gabapentin prescriptions that were completed during the 7-month period from October 2002 through April 2003, 60 (40%) were denied, which resulted in the lack of gabapentin use in these 60 patients. CONCLUSIONS: A clinical pharmacy intervention as part of the management of a treatment guideline for appropriate gabapentin use promotes documentation of drug therapy effectiveness in neuropathic pain and prevention of gabapentin use prior to a trial with alternative first-line therapies.