A 20 mg dose of dexamethasone does not reduce the proportion of joint replacement patients needing rescue analgesia: a matched cohort study.

Background: Consistent pain control after total joint replacement (TJR) has not yet been reached in all patients managed with a multimodal analgesia regime. Questions remain on dosage and timing of analgesics. Glucocorticoids such as dexamethasone are considered most powerful in reducing the surgery-induced inflammatory response with most pain studies using a 6-12 mg dose. Reviews agree that additional glucocorticoids may provide more analgesia, but a dose-finding analysis is limited. The primary aim of this study was to determine if a high, single preoperative dose of dexamethasone resulted in a reduced need for rescue analgesics during the first 24 hours after TJR when compared to a standard 8 mg dose of dexamethasone.

Methods: A cohort study in which 59 patients who received 20 mg dexamethasone intravenously just prior to incision were matched 1:1 to patients who received a standard 8 mg dose. Consecutive elective hip and knee replacement patients managed by one anaesthesiologist were included in the high dose group between June 2019 and March 2020. Patients were matched for arthroplasty type, gender, age, anaesthesia type and pre-operative pain. Patients with opioid use before surgery or with diabetes mellitus were excluded. Oxynorm rescues analgesics (number of times given and dosage) usage during hospitalization was retrieved from the electronic nursing files.

Results: There were no significant differences between groups in gender distribution, mean age and body mass index (BMI), in American Society of Anesthesiologists (ASA), type of arthroplasty, anaesthesia type and pre-operative pain score. In the 20 mg group 54 patients (91.5%) needed oxynorm during hospitalization versus 58 (98.3%) in the 8 mg group (P=0.09). High dose group patients received a median of 5 mg [interquartile range (IQR): 0] oxynorm versus 5 mg (IQR: 0) in the standard dose group (P=0.70).

Conclusions: In this matched cohort study there was no difference in the proportion of patients needing rescue analgesics during hospitalization between the group of patients who preoperatively received 20 mg dexamethasone and the group of patients who received 8 mg. Future blinded randomized controlled trials are needed to further investigate the effect of different glucocorticoids dosages on pain after joint replacement surgery.