Characterization of self-anticipated pain score prior to elective surgery - a prospective observational study

Abstract

Background: Current principles of postoperative pain management are primarily based on the types and extent of surgical intervention. This clinical study measured patient's self-anticipated pain score before surgery, and compared the anticipated scores with the actual pain levels and analgesic requirements after surgery.

Methods: This prospective observational study recruited consecutive patients who received elective surgery in the E-Da Hospital, Taiwan from June to August 2018. Patients were asked to subjectively rate their highest anticipated pain level (numeric rating scale, NRS 0-10) for the scheduled surgical interventions during their preoperative anesthesia assessment. After the operation, the actual pain intensity (NRS 0-10) experienced by the patient in the post-anesthesia care unit and the total dose of opioids administered during the perioperative period were recorded. Pain scores ≥4 on NRS were regarded as being unacceptable levels for anticipated or postoperative pain that required more aggressive intervention.

Results: A total of 996 patients were included in the study. Most of the patients (86%) received general anesthesia and 73.9% of them had a history of previous operation. Female anticipated significantly higher overall pain intensities than the male patients (adjusted odd ratio 1.523, 95% confidence interval 1.126-2.061; P = 0.006). Patients who took regular benzodiazepine at bedtime (P = 0.037) and those scheduled to receive more invasive surgical procedures were most likely to anticipate for higher pain intensity at the preoperative period (P < 0.05). Higher anticipated pain scores (preoperative NRS ≥ 4) were associated with higher actual postoperative pain levels (P = 0.007) in the PACU and higher total equivalent opioid use (P < 0.001) for acute pain management during the perioperative period.

Conclusion: This observational study found that patients who are female, use regular benzodiazepines at bedtime and scheduled for more invasive surgeries anticipate significantly higher surgery-related pain. Therefore, appropriate preoperative counseling for analgesic control and the management of exaggerated pain expectation in these patients is necessary to improve the quality of anesthesia delivered and patient's satisfaction.

Keywords: Numeric rating scale; Pain expectation; Pre-anesthesia assessment, post-anesthesia care unit; Surgery-related pain.

Fig. 1

Specific aims of the study. The clinical variables that might be associated with increased anticipated pain were defined as patient’s characteristics, anesthesia-related and surgical related factors

Fig. 2

Study flow diagram

Fig. 3

Graphical presentation of relationships between types of the scheduled surgery and patient’s anticipated pain. The invasiveness of surgical procedures graded by a clinical prediction model established by Janssen and his colleageus [22], as types of operation were grouped into the lowest, low, moderate, high and highest expected pain surgery. The median value of anticipated numeric rating scale (NRS) in the lowest expected pain surgery group was significantly increased in comparison to the other groups (*P < 0.05 and **P < 0.001; as analyzed using the Kruskal-Wallis test, followed by the Dunn’s post-hoc test). Results are presented as box-and-whisker plots, in which the horizontal solid lines of boxes indicate the 75th percentile, median and 25th percentile of the distribution, and the upper and lower whiskers indicate the maximal and minimal values. Dotted lines indicate the mean values