Relationship between intensity and relief in patients with acute severe pain.
OBJECTIVE
To test whether a single-category improvement on a Likert pain relief scale equals the minimum clinically significant difference of 1.3 units in pain intensity reduction on a 10-unit numerical rating scale (NRS).


METHODS
Prospective cohort of adults with acute severe pain receiving standardized analgesia. Patients rated pain intensity via NRS before receiving morphine and 30 minutes later. Patients described pain relief as "none," "a little," "moderate," "a lot," or "complete." The primary outcome was the difference in NRS scores between each contiguous pair of pain relief categories over 30 minutes.


RESULTS
One hundred thirty-one patients, age range 21 to 65 years, median baseline NRS pain score 10 (interquartile range, 9-10). Patients whose relief was "complete," "a lot," "moderate," "mild," and "none" had the following NRS unit reductions in pain, respectively: 9, 5.7, 3.9, 2.1, and -0.1. The difference between each pair of relief categories was 3.3, 1.8, 1.8, and 2.2 units.


CONCLUSIONS
Each single-category improvement on a pain relief scale exceeds the minimum clinically significant difference in pain intensity as measured on an NRS.
Bernstein
Steven L
SL
Department of Emergency Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY 10467, USA. sbernste@montefiore.org
Bijur
Polly E
PE
Gallagher
E John
EJ
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement / Q000379:methods*; D011446:Prospective Studies; D012107:Research Design; D015983:Selection Bias
D000701:Analgesics, Opioid; D009020:Morphine