Shifts in Pain Severity Categories among Patients with Painful Diabetic Peripheral Neuropathy or Postherpetic Neuralgia Treated with Pregabalin (P7.312)

BACKGROUND: Efficacy of pregabalin has been demonstrated in placebo-controlled trials of painful diabetic peripheral neuropathy (DPN) and postherpetic neuralgia (PHN). Efficacy is based on statistically significant differences in pain scores between pregabalin- and placebo-treated patients. However, statistically significant pain relief may not always represent clinically meaningful relief. OBJECTIVE: We examined shifts in pain severity categories among DPN and PHN patients treated with pregabalin. METHODS: Data were pooled from 16 placebo-controlled trials of pregabalin for DPN or PHN. Treatment arms included placebo (n=1532), pregabalin 150 mg/d (n=427), pregabalin 300 mg/d (n=875), pregabalin 600 mg/d (n=861), and flexible pregabalin 150-600 mg/d (n=704). Pain scores were categorized as mild (0 to <4), moderate (4 to 7), or severe (>7 to 10). Only patients reporting moderate or severe pain at baseline were analyzed (protocol inclusion criteria). The percentage of patients shifting from moderate or severe at baseline to mild, moderate, or severe at endpoint (BOCF) were calculated for each treatment arm. Treatment arms were compared with placebo using a Cochran-Mantel-Haenszel test (modified ridit transformation of the calculated ordinal shift scales). RESULTS: Significantly more patients shifted to a less severe pain category at endpoint in the pregabalin treatment groups compared with placebo (all p≤0.0012). This was especially evident in the 300-, 600-, and 150-600 mg/d pregabalin arms. The percentage of patients shifting from severe at baseline to mild at endpoint was 28% for pregabalin 300 mg/d, 37% for pregabalin 600 mg/d, and 36% for pregabalin 150-600 mg/d compared to only 17% for placebo. Additionally, the percentage of patients shifting from moderate at baseline to mild at endpoint was 59% for pregabalin 150-600 mg/d compared to only 41% for placebo. CONCLUSIONS: Pregabalin treatment is associated with beneficial shifts in pain severity categories, compared with placebo, among patients with painful DPN or PHN. Sponsored by Pfizer Inc.