Predicting severe pain after cesarean section: prospective cohort study

Abstract

BACKGROUND: Severe and unbearable pain after abdominal delivery is recorded in 20% of cases, indicating the limitations of the applied methods of postoperative pain relief and the need for a personalized approach. Tests assessing preoperative pain threshold and anxiety have the greatest sensitivity and specificity as predictors of intense postoperative pain. The informative value of these tests in the Russian obstetric population has not been assessed.
 OBJECTIVE: This study aimed to determine the optimal method for predicting severe pain after cesarean section (CS).
 MATERIALS AND METHODS: This prospective cohort study included 212 women who underwent elective CS under spinal anesthesia. The Hospital Anxiety and Depression Scale (HADS) anxiety rating scale, pressure algometry, and cutaneous infiltration anesthesia pain intensity assessment were used as predictors of high-intensity pain. Postoperative pain intensity was assessed using a 10-point Numeric Rating Scale (NRS). The maximum level of pain according to the central pain level at rest (NRSr) and during movement (NRSa) was recorded 24 hour postoperatively. The number of requests for “rescue analgesia” was recorded. The predictive value of the studied methods was determined based on ROC curve analysis.
 RESULTS: Median (interquartile range) NRSa was 5 [4–5]. Severe pain was recorded in 14% of the patients. The area under the ROC-curve (AUC), reflecting the relationship between severe postoperative pain and pressure-pain threshold, was 0.91±0.03 with 95% confidence interval (CI) of 0.84–0.97 (p 0.001). The relationship between pain intensity during infiltration anesthesia and postoperative pain severity had AUC=0.88 ± 0.04 with 95% CI of 0.81–0.96 (p 0.001). The HADS anxiety score demonstrated the lowest predictive ability (AUC=0.69±0.06; 95% CI, 0.81–0.96; p 0.001). When all three techniques were used together, the AUC was 0.924±0.024 with 95% CI 0.88–0.97 (p=0.001).
 CONCLUSION: Preoperative pressure-pain threshold and pain severity during infiltration anesthesia are reliable predictors of severe pain after CS. Assessment of preoperative anxiety using HADS has low sensitivity and specificity. However, its use in conjunction with methods for assessing the pain threshold increases the predictive value of the combined model compared with the results of using the methods separately.