-
[show abstract]
[hide abstract]
ABSTRACT: Objective. The aim of this study is to assess the Pain Quality Assessment Scale (PQAS) in predicting pregabalin in peripheral neuropathic pain (NP). Study Design. Post hoc analysis of a double-blind, placebo-controlled, enriched enrollment, randomized withdrawal trial evaluating pregabalin in 99 patients with NP who completed the PQAS, which comprises 20 questions regarding individual pain domains and qualities that are scored into three scales: paroxysmal, deep, and surface. Methods. Patients rated the average pain intensity and pain quality using the PQAS at baseline; average pain intensity was assessed again after 40 days of treatment with pregabalin. Associations between pretreatment PQAS scores and treatment response were estimated using Pearson's r. Logistic regression was used to identify pretitration PQAS scores contributing unique variance to predicting treatment response. Results. Fifty participants provided baseline PQAS scores and received pregabalin for the entire length of the study. Nine of 23 PQAS baseline scales and items were significantly associated with treatment response to pregabalin: the paroxysmal and deep scales, and the items assessing the following pain domains and qualities: intensity, electric, tingling, cramping, radiating, throbbing, and deep (P values range, 0.002-0.045; rs range, 0.28-0.43). The PQAS items assessing sharp, hot, and unpleasant pain items demonstrated nonsignificant trends (P < 0.10) to be associated with treatment response. In the logistic regression analysis, pretitration PQAS scores had 77% sensitivity and 83% specificity to correctly identify pregabalin responders. Significantly correlated PQAS items had a sensitivity of 85% and specificity of 76%. Conclusion. Pretitration PQAS scores reliably predicted pregabalin responders in patients with NP.
Pain Medicine 07/2012; · 2.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To identify and describe the response profile of pregabalin on the qualities of pain associated with peripheral neuropathy.
A post hoc analysis to examine the effects of pregabalin on pain quality in patients with moderate-to-severe peripheral neuropathic pain was performed using data from an enriched enrollment randomized withdrawal proof-of-concept study. Patients rated the quality of their pain experience using the Pain Quality Assessment Scale (PQAS) at baseline, after a 12-day titration period, after a 9-day maintenance period, and after a 19-day randomized withdrawal period. Pretitration to posttitration and prewithdrawal to postwithdrawal changes in PQAS paroxysmal, surface, and deep pain scale scores were examined.
PQAS data were available for 99 of the 104 participants who entered all phases of the study. There were significant (P<0.006, Bonferroni adjusted for multiple tests) improvements pretitration to posttitration in all 3 PQAS subscales, with a greater effect on paroxysmal and deep pain than on surface pain. During the withdrawal phase, pregabalin was significantly (P<0.006) more effective than placebo for improvements in paroxysmal and surface pain only, although the pregabalin group continued to show numerical improvement in deep pain relative to placebo.
Pregabalin had a greater effect on PQAS-assessed paroxysmal pain than on surface or deep pain in patients with peripheral neuropathy. The findings corroborate previous research demonstrating differential effects of analgesic drugs across pain qualities, further emphasizing the need to assess individual pain qualities in addition to overall pain intensity.
The Clinical journal of pain 12/2011; 28(8):683-6. · 3.01 Impact Factor
-
David J Hewitt,
Tony W Ho,
Bradley Galer,
Miroslav Backonja,
Paul Markovitz,
Arnold Gammaitoni,
David Michelson,
James Bolognese, Achilles Alon,
Elizabeth Rosenberg,
Gary Herman,
Hao Wang
[show abstract]
[hide abstract]
ABSTRACT: The objective of this study was to evaluate how enrichment for responders increases assay sensitivity in an enriched enrollment randomized withdrawal (EERW) proof-of-concept (POC) study in neuropathic pain. Adults with moderate to severe peripheral neuropathic pain entered a 3- to 4-day screening period, followed by a 12-day titration to the highest tolerated dose that provided pain control (pregabalin 50-200mg t.i.d.), and then a 9-day maintenance period. Subjects were stratified as primary responders (⩾30%), secondary responders (⩾10% to <30%), or nonresponders (<10%) based on decrease in pain intensity and were randomized to placebo or pregabalin during the randomized withdrawal period. The primary endpoint was mean of average 24-h pain intensity during the last 3days of treatment period relative to the 3days before randomization. Time-to-efficacy-failure was the key secondary endpoint. Other features included not requiring discontinuation of current analgesic therapies and blinding investigators to study design elements that could contribute to non-treatment-related responses. Effect size (ES) (mean treatment difference/SD) was used to measure assay sensitivity. Pregabalin-treated subjects (n=52) had significantly less pain than those receiving placebo (n=51) (P⩽.003). Effect size of the primary endpoint was 0.72 for primary responders and decreased if secondary and nonresponders were included in the analysis. The highest ES (1.68) was demonstrated for the endpoint time-to-efficacy-failure seen in primary responders with painful diabetic neuropathy. The EERW trial design using time-to-efficacy-failure may provide a sensitive and efficient method to conduct POC studies of novel therapies in patients with neuropathic pain. Enriching a study population with patients who have achieved a 30% decrease in pain with an investigational therapy, and using time-to-efficacy-failure during the randomized withdrawal phase as the primary endpoint, can be used for a proof-of-concept study to optimize assay sensitivity and efficiently determine the analgesic potential of a new treatment for neuropathic pain.
Pain 03/2011; 152(3):514-21. · 5.78 Impact Factor
