Of Rough Starts and Smooth Finishes: Correlations Between Post-Anesthesia Care Unit and Postoperative Days 1-5 Pain Scores

Abstract

The goal of this project was to explore the association between post-anesthesia care unit (PACU) pain scores recorded within the first and second hour of the end of surgery with maximum and median pain scores recorded on postoperative days (PODs) 1 through 5. This study was a retrospective cohort study of clinically documented pain scores in a mixed surgical population. This study was set in a single tertiary-care teaching hospital over a 1-year time period. All patients were adult patients undergoing a single, non-ambulatory, non-obstetric surgical procedure. Pain scores, measured using the numerical rating scale, from PODs 0 through 5 were obtained from an integrated data repository. Kendall's Tau-b correlations were then calculated between maximum pain scores occurring within each of the two PACU time periods and maximum and median pain scores in each of the five ensuing PODs. A total of 349,797 pain scores from 8,332 patients were reviewed. Correlations between maximum pain score by time period demonstrated a significant and high correlation at Tau-b = 0.86, between 1-hour PACU pain scores and 2-hour PACU pain scores. However, the correlation of maximum pain scores recorded in the PACU with those recorded on PODs 1 through 5 was significantly lower, ranging from 0.19 to 0.27. The correlation of maximum PACU pain score with median pain scores recorded on PODs 1 through 5 ranged from 0.22 to 0.29. The correlation structures of the PODs 1 through 5 median pain scores may be consistent with an autoregressive pattern. Maximum scores measured within the PACU likely reflect a set of circumstances distinct from those experienced on PODs 1 through 5.