The exploration of the establishment of cutpoints to categorize the severity of acute postoperative pain

Objectives: Although several studies have established different cutpoints (Cps) for mild, moderate, and severe pain for a variety of chronic pain conditions, only one study by Mendoza and colleagues reported on CPs for acute postoperative pain that were derived using ratings of worst pain. The purpose of this study was to explore the establishment of the optimal CPs for mild, moderate, and severe postoperative pain using ratings of average and worst pain and to determine if these CPs distinguished among the pain severity groups on several outcomes. Methods: The study is a reanalysis of data from patients who underwent hip and knee replacement surgery. Using the methodology described by Serlin et al, a series of CP derivations were performed based on both single item scores for pain intensity and mean scores for pain intensity. One-way analyses of variance, chi(2) analyses, or Kruskal-Wallis tests were conducted to determine if the optimal CPs for pain severity distinguished among the 3 pain severity groups on several outcomes. Results: Cps 3,5 were found using a mean score based on patients' ratings of average and worst pain on the third postoperative day. Findings suggest that mean pain scores of > 3 have a significant effect on general activity, mood, walking ability, and sleep. Discussion: Possible explanations for the differences in the Cps found in this study compared with the results by Mendoza and colleagues are discussed. The findings warrant replication in other samples of postoperative patients.