What decline in pain intensity is meaningful to patients with acute pain?

TLDR

The 0‑10 numeric rating scale is widely used, yet the clinical significance of pain score reductions to patients is poorly understood. The study sought to determine how patients interpret reductions in pain intensity and percent pain relief. Seven hundred postoperative patients in the PACU rated baseline pain on a 0‑10 NRS and a 4‑point verbal scale, received opioids until pain ≤4/10, and reported pain and improvement every 10 min during titration. In moderate‑pain patients, a 1.3‑point (20%) decrease is minimal, 2.4‑point (35%) is much, and 3.5‑point (45%) is very much improvement, while severe‑pain patients require larger reductions, indicating that the clinically meaningful change rises with baseline severity and can guide efficacy assessment.

Abstract

Despite widespread use of the 0-10 numeric rating scale (NRS) of pain intensity, relatively little is known about the meaning of decreases in pain intensity assessed by means of this scale to patients. We aimed to establish the meaning to patients of declines in pain intensity and percent pain reduction. Upon arrival to the postanesthesia care unit, postsurgical patients rated their baseline pain intensity on both a 0-10 NRS and on a 4-point verbal scale. Patients whose NRS was higher than 4/10 received intravenous opioids until their pain intensity declined to 4/10 or lower. During opioid titration, patients were asked every 10 min to rate pain intensity on a NRS and to indicate the degree of pain improvement on a 5-point Likert scale from 'no improvement' to 'complete pain relief'. Seven hundred adult patients were enrolled. For patients with moderate pain, a decrease of 1.3 units (20% reduction) corresponded to 'minimal' improvement, a decrease of 2.4 (35% reduction) to 'much' improvement, a decrease of 3.5 units (45% reduction) corresponded to 'very much' improvement. For patients with severe pain, the decrease in NRS pain score and the percentage of pain relief had to be larger to obtain similar degrees of pain relief. The change in pain intensity that is meaningful to patients increases as the severity of their baseline pain increases. The present findings are applicable in the clinical setting and research arena to assess treatment efficacy.