Duloxetine combined with intra-articular injection versus intra-articular injection alone for pain relief in knee osteoarthritis: a study protocol for a randomised controlled trial

INTRODUCTION: Intra-articular (IA) injection of hyaluronic acid (HA) and corticosteroid (CS) is a common treatment for osteoarthritis (OA) of the knee. As a drug treatment for patients with depression, duloxetine has been shown in many studies to effectively relieve the pain of OA and improve function of the knee joint. However, evidence regarding the efficacy of IA injection of HA+CS combined with duloxetine for pain management in patients with OA of the knee is lacking. The aim of this study was to test the hypothesis that IA injection of HA+CS combined with duloxetine could achieve pain management superior to that of IA injection of HA+CS alone in patients experiencing knee OA pain. METHODS: This study will adopt a prospective, randomised, open-label blind endpoint study design. In total, 150 patients with OA of the knee will be enrolled in the study. The participants will be randomly allocated to receive either a single IA injection of HA+CS combined with duloxetine or a single IA injection of HA+CS alone, and both groups will complete a 24-week follow-up to assess pain and functional improvements. The primary outcome measure is the change in the weekly mean of the 24 hours average pain scores from baseline to the end of 24 weeks in patients with OA of the knee, and the secondary outcomes include the response to treatment, changes from baseline in the brief pain inventory, improvement in the Western Ontario and McMaster Universities Osteoarthritis index scores, patient global impression of improvement scale, Hospital Anxiety and Depression Scale and adverse events during the 24-week follow-up. The data will be analysed by the intention-to-treat principle. ETHICS APPROVAL AND DISSEMINATION: This study was approved by the institutional ethics committee of the Beijing Tiantan Hospital (approval number: KY 2019-086-02). The results of the study will be published in peer-reviewed journals, and the findings will be presented at scientific meetings. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Identifier: NCT04117893; Pre-results.