Predicting acute pain after cesarean delivery using three simple questions

Abstract

Background: Interindividual variability in postoperative pain presents a clinical challenge. Preoperative quantitative sensory testing is useful but time consuming in predicting postoperative pain intensity. The current study was conducted to develop and validate a predictive model of acute postcesarean pain using a simple three-item preoperative questionnaire.

Methods: A total of 200 women scheduled for elective cesarean delivery under subarachnoid anesthesia were enrolled (192 subjects analyzed). Patients were asked to rate the intensity of loudness of audio tones, their level of anxiety and anticipated pain, and analgesic need from surgery. Postoperatively, patients reported the intensity of evoked pain. Regression analysis was performed to generate a predictive model for pain from these measures. A validation cohort of 151 women was enrolled to test the reliability of the model (131 subjects analyzed).

Results: Responses from each of the three preoperative questions correlated moderately with 24-h evoked pain intensity (r = 0.24-0.33, P < 0.001). Audio tone rating added uniquely, but minimally, to the model and was not included in the predictive model. The multiple regression analysis yielded a statistically significant model (R = 0.20, P < 0.001), whereas the validation cohort showed reliably a very similar regression line (R = 0.18). In predicting the upper 20th percentile of evoked pain scores, the optimal cut point was 46.9 (z =0.24) such that sensitivity of 0.68 and specificity of 0.67 were as balanced as possible.

Conclusions: This simple three-item questionnaire is useful to help predict postcesarean evoked pain intensity, and could be applied to further research and clinical application to tailor analgesic therapy to those who need it most.

Figures

Fig. 1

Flow chart for subject inclusions and exclusions for derivation and validation cohorts.

Fig. 2

(A) Linear regression line plot between predicted and actual 24-h evoked pain intensity (visual analog scale) in the derivation cohort (n = 192, R2 = 0.20, P < 0.001) and the validation cohort (n = 131, R2 = 0.18, P < 0.001). R2 = the variance in pain outcome accounted for by the predictors. (B) 24-h evoked pain outcome predicted value residual plots of both derivation and validation cohorts.

Fig. 3

Receiver operator characteristic curves of both derivation (n = 192) and validation (n = 131) cohorts.