Development and Internal Validation of the Postoperative Analgesic Intake Needs Score: A Predictive Model for Post-Operative Narcotic Requirement after Spine Surgery

Abstract

Study Design Retrospective Cohort. Objective The aim of this study was to develop a clinical tool to pre-operatively risk-stratify patients undergoing spine surgery based on their likelihood to have high postoperative analgesic requirements. Methods A total of 1199 consecutive patients undergoing elective spine surgery over a 2-year period at a single center were included. Patients not requiring inpatient admission, those who received epidural analgesia, those who had two surgeries at separate sites under one anesthesia event, and those with a length of stay greater than 10 days were excluded. The remaining 860 patients were divided into a derivation and validation cohort. Pre-operative factors were collected by review of the electronic medical record. Total postoperative inpatient opioid intake requirements were converted into morphine milligram equivalents to standardize postoperative analgesic requirements. Results The postoperative analgesic intake needs (PAIN) score was developed after the following predictor variables were identified: age, race, history of depression/anxiety, smoking status, active pre-operative benzodiazepine use and pre-operative opioid use, and surgical type. Patients were risk-stratified based on their score with the high-risk group being more likely to have high opioid consumption postoperatively compared to the moderate and low-risk groups in both the derivation and validation cohorts. Conclusion The PAIN Score is a pre-operative clinical tool for patients undergoing spine surgery to risk stratify them based on their likelihood for high analgesic requirements. The information can be used to individualize a multi-modal analgesic regimen rather than utilizing a “one-size fits all” approach.