GABAPENTIN FOR THE SYMPTOMATIC TREATMENT OF PAINFUL NEUROPATHY IN PATIENTS WITH DIABETES-MELLITUS - A RANDOMIZED CONTROLLED TRIAL

Context.-Pain is the most disturbing symptom of diabetic peripheral ne uropathy. As many as 45% of patients with diabetes mellitus develop pe ripheral neuropathies. Objective.-To evaluate the effect of gabapentin monotherapy on pain associated with diabetic peripheral neuropathy. D esign.-Randomized, double-blind, placebo-controlled, 8-week trial cond ucted between July 1996 and March 1997, Setting.-Outpatient clinics at 20 sites. Patients.-The 165 patients enrolled had a 1- to 5-year hist ory of pain attributed to diabetic neuropathy and a minimum 40-mm pain score on the Short-Form McGill Pain Questionnaire visual analogue sca le. Intervention.-Gabapentin (titrated from 900 to 3600 mg/d or maximu m tolerated dosage) or placebo. Main Outcome Measures.-The primary eff icacy measure was daily pain severity as measured on an 11-point Liker t scale (0, no pain; 10, worst possible pain), Secondary measures incl uded sleep interference scores, the Short-Form McGill Pain Questionnai re scores, Patient Global impression of Change and Clinical Global Imp ression of Change, the Short Form-36 Quality of Life Questionnaire sco res, and the Profile of Mood States results. Results.-Eighty-four pati ents received gabapentin and 70 (83%) completed the study; 81 received placebo and 65 (80%) completed the study. By intent-to-treat analysis , gabapentin-treated patients' mean daily pain score at the study end point (baseline, 6.4; end point, 3.9; n = 82) was significantly lower (P<.001) compared with the placebo-treated patients' end-point score ( baseline, 6.5; end point, 5.1; n = 80). All secondary outcome measures of pain were significantly better in the gabapentin group than in the placebo group. Additional statistically significant differences favor ing gabapentin treatment were observed in measures of quality of life (Short Form-36 Quality of Life Questionnaire and Profile of Mood State s). Adverse events experienced significantly more frequently in the ga bapentin group were dizziness (20 [24%] in the gabapentin group vs 4 [ 4.9%] in the control group; P<.001) and somnolence (19 [23%] in the ga bapentin group vs 5 [6%] in the control group; P = .003). Confusion wa s also more frequent in the gabapentin group (7 [8%] vs 1 [1.2%]; P = .06). Conclusion.-Gabapentin monotherapy appears to be efficacious for the treatment of pain and sleep interference associated with diabetic peripheral neuropathy and exhibits positive effects on mood and quali ty of life.