(342) Measurement of affective, sensory and evaluative dimensions of pain using a Qualities-of-Pain Index (QPI)

Abstract

Patients express painful experiences using affective and sensory descriptors, not just evaluative terms. Previously, we demonstrated the sensitivity of a qualities-of-pain index comparing the effects of 1 dose of a standard analgesic, hydrocodone 7.5 mg/acetaminophen 325 mg (HC/APAP) to placebo.1 To evaluate changes in these qualitative dimensions of pain over 48 hours, we augmented the design of an analgesic study2 with measurements of these other pain descriptors. After primary unilateral metatarsal bunionectomy, 302 qualifying patients aged ≥18 years with moderate-to-severe pain (on a numerical rating scale, PI-NRS) were randomized to CL-108 (HC/APAP with rapid-release promethazine 12.5mg) or placebo under double-blind conditions, 1 dose every 4–6 hours (up to 6 doses/24 hours). In addition to regularly-scheduled measurements on the PI-NRS, at baseline and 6, 12, 24, and 48 hours after treatment, patients used a separate 0–10 Likert scale in the QPI to rate each quality of pain: affective (annoying, agonizing) sensory (throbbing, heavy, swollen, tight, sharp, hot, pulling, stabbing, pressing, stinging, radiating) and evaluative (aching, hurting). Changes in QPI scores (the sum of all quality-of-pain scales) were compared for all patients regardless of baseline values. QPI scores for CL-108–treated patients were reduced compared with placebo over 24 hours (−45.8% vs −16.2%) and 48 hours (−55.0% vs −35.0%, both p≤0.004), correlating with results on the PI-NRS (both r>0.80, p<0.001). Compared with placebo, CL-108 also reduced the affective (−46.9% vs −14.0%), sensory (−43.4% vs −12.5%), and evaluative (−44.0% vs −17.3%) QPI sub-scores over 24 hours (all p<0.001). We conclude that the QPI is a sensitive indicator of changes in qualities of pain over 6–48 hours and that this instrument can be used to demonstrate the acute analgesic efficacy of opioid medications like CL-108. Funded by Charleston Laboratories, Inc., and Daiichi Sankyo, Inc. (1. Schachtel, J Pain, 2015 2. Richardson, J Pain, 2016)