Visual Analog Scales for Assessing Surgical Pain

Abstract

BACKGROUND: Four visual analog scales were constructed to assess sensory and affective components of operative pain. The Surgical Pain Scales (SPS) measure pain while at rest, pain during normal activities, pain during work or exercise, and pain unpleasantness. STUDY DESIGN: Longitudinal data from 2,164 patients in a randomized trial of laparoscopic versus open hernia repair established the reliability, validity, and sensitivity to change of the SPS. Correlations and t-tests were used to determine their psychometric properties compared with the SF-36 health status instrument. RESULTS: Intraclass correlation coefficients of 0.95 for the sensory scales and 0.94 for the unpleasantness rating confirmed that the SPS produced reliable measurements. Correlations ranging from 0.44 to 0.60 between the visual analog scales and the bodily pain dimension on the SF-36 and significant differences between SPS levels for patients requiring more and less time to resume normal activities (p< or =0.015 to p< or =0.002) supported the validity of the scales. Clinical responsiveness was demonstrated by a 33.5-mm reduction (standard error = 1.4 mm) in the mean rating on a 150-mm scale measuring pain during normal activities for patients reporting postoperative improvement on the bodily pain dimension (p< or =0.0001). CONCLUSIONS: The Surgical Pain Scales demonstrated excellent psychometric properties in this study population. The SPS can be used to compare pain levels between groups at a single point in time or to track change for individual patients over time or after operations. Individualized pain management interventions can be tailored based on the sensory and effective ratings.