Of rough starts and smooth finishes: correlations between post-anesthesia care unit and postoperative days 1-5 pain scores.

OBJECTIVE: 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.
DESIGN: This study was a retrospective cohort study of clinically documented pain scores in a mixed surgical population.
SETTING: This study was set in a single tertiary-care teaching hospital over a 1-year time period. PATIENTS: All patients were adult patients undergoing a single, non-ambulatory, non-obstetric surgical procedure. MEASURES: 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.
RESULTS: 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.
CONCLUSIONS: Maximum scores measured within the PACU likely reflect a set of circumstances distinct from those experienced on PODs 1 through 5. Wiley Periodicals, Inc.