Performance characteristics and validation of the Opioid-Related Symptom Distress Scale for evaluation of analgesic side effects after orthopedic surgery.

BACKGROUND: The Opioid-Related Symptom Distress Scale (ORSDS) is a 4-point scale that evaluates 3 symptom distress dimensions (frequency, severity, bothersomeness) for 12 symptoms. The symptom-specific ORSDS is the average of the 3 symptom distress dimensions. The composite ORSDS is the average of 12 symptom-specific scores. The ORSDS was validated for outpatient laparoscopic cholecystectomy (under general anesthesia) by assessment of internal consistency, content validity, construct validity, principal components analysis, known group validity, responsiveness, and opioid dose dependency. Additional validation studies were suggested. We investigated performance characteristics and validity of the ORSDS for postoperative analgesia after 4 types of anesthetic and analgesic regimens.
METHODS: The ORSDS and validation questions were administered to 4 groups of 50 orthopedic patients. Peripheral nerve blockade (Peripheral) was performed for distal upper extremity surgery; neuraxial anesthesia (Neuraxial) was performed for anterior cruciate ligament reconstruction; combined spinal-epidural anesthesia/femoral nerve block/epidural analgesia (Regional) was performed for total knee arthroplasty; and general anesthesia/IV opioids (GA) was performed for posterior lumbar spine fusion. All patients also received oral opioid analgesics.
RESULTS: Median composite ORSDS scores on postoperative day 1 were 0.19 (Peripheral), 0.52 (Neuraxial), 0.51 (Regional), and 0.94 (GA). The following symptoms had median symptom-specific ORSDS scores >0: Neuraxial = drowsiness, dry mouth; Regional = dizziness, dry mouth; GA = nausea, fatigue, dizziness, drowsiness, dry mouth. Problematic symptoms (symptoms for which at least 25%of patients reported symptom-specific ORSDS scores >1) were: all groups = drowsiness, dry mouth, fatigue; Neuraxial = nausea, dizziness, itchiness; Regional = nausea, dizziness, itchiness; GA = difficulty concentrating, headache, nausea, dizziness, itchiness. High symptom-specific ORSDS scores were associated with clinically meaningful adverse events. In some cases, relevant ORSDS scores were related to activity level, patient satisfaction, and nausea and vomiting measures. Many components occurred in correlated clusters. Responsiveness statistics (the ability of an instrument to detect changes once they have occurred) were high for nausea and vomiting. Linear regression analysis indicated that opioid use was associated with composite ORSDS scores for Peripheral, Regional, and GA.
CONCLUSIONS: Validity of the ORSDS was supported by predetermined validation criteria, including measures of internal consistency, content validity, construct validity, principal components analysis, known group validity, responsiveness, and correlation with opioid intake. The ORSDS is a valid tool for assessment of opioid side effects after orthopedic surgery, and can be used in clinical trials involving a wide variety of anesthetic and analgesic regimens.