Reliability of the visual analog scale for measurement of acute pain.
OBJECTIVE
Reliable and valid measures of pain are needed to advance research initiatives on appropriate and effective use of analgesia in the emergency department (ED). The reliability of visual analog scale (VAS) scores has not been demonstrated in the acute setting where pain fluctuation might be greater than for chronic pain. The objective of the study was to assess the reliability of the VAS for measurement of acute pain.


METHODS
This was a prospective convenience sample of adults with acute pain presenting to two EDs. Intraclass correlation coefficients (ICCs) with 95% confidence intervals (95% CIs) and a Bland-Altman analysis were used to assess reliability of paired VAS measurements obtained 1 minute apart every 30 minutes over two hours.


RESULTS
The summary ICC for all paired VAS scores was 0.97 [95% CI = 0.96 to 0.98]. The Bland-Altman analysis showed that 50% of the paired measurements were within 2 mm of one another, 90% were within 9 mm, and 95% were within 16 mm. The paired measurements were more reproducible at the extremes of pain intensity than at moderate levels of pain.


CONCLUSIONS
Reliability of the VAS for acute pain measurement as assessed by the ICC appears to be high. Ninety percent of the pain ratings were reproducible within 9 mm. These data suggest that the VAS is sufficiently reliable to be used to assess acute pain.
Bijur
P E
PE
Department of Emergency Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA. bijur@aecom.yu.edu
Silver
W
W
Gallagher
E J
EJ
D000208:Acute Disease; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis* / Q000453:epidemiology*; D010147:Pain Measurement / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index