Does Duration of Neuropathic Pain Impact the Effectiveness of Pregabalin?

Background Patients with chronic pain conditions such as neuropathic pain frequently experience delays in diagnosis and treatment. Ideally, all patients should be treated in a timely manner, but in those patients with more established disease it is important to know that approved treatments remain effective. Methods This was a pooled analysis of 19 randomized placebo-controlled trials of pregabalin for peripheral neuropathic pain conditions, including diabetic peripheral neuropathy, postherpetic neuralgia, and post-traumatic/postsurgical pain. Patients were divided into 5 pain duration categories based on time since onset of pain (< 6 months, 6 months to < 1 year, 1 year to < 2 years, 2 years to < 5 years, and ≥ 5 years). Mean change in pain score at endpoint, vs. placebo, was assessed for each category, together with changes in Patient Global Impression of Change ( PGIC) responders ('very much' or 'much' improved at endpoint). Results The analysis included 5,783 patients ( n = 3,619 pregabalin; n = 2,164 placebo). Mean baseline pain scores were similar across the pain duration categories (range 6.3 to 6.5). Pregabalin significantly improved pain score at endpoint, vs. placebo, in all patients together (treatment difference [95% confidence interval], −0.59 [−0.67, −0.52], P < 0.0001) and similarly in each pain duration category ( P < 0.0001 for each). There were significantly more PGIC responders with pregabalin, vs. placebo, for all patients (45.0% vs. 30.9%, P < 0.0001) and each category separately ( P < 0.001 for each). There were no consistent, significant differences in treatment response between the different pain duration categories. Conclusions Pregabalin significantly improves pain irrespective of the length of time since onset of neuropathic pain. [ABSTRACT FROM AUTHOR]