Duloxetine for Pain in Older Adults With Knee Osteoarthritis (OA)

Overview

Osteoarthritis (OA), a common disabling condition, is the commonest type of arthritis worldwide.Pain is the leading symptom and is often chronic in na. Current treatment options have had limited symptomatic effect and are associated with significant side effects. Duloxetine, a selective serotonin norepinephrine reuptake inhibitor has been demonstrated to have, besides its antidepressant properties, a centrally acting analgesic effect. The aim of the present study was to investigate the efficacy of duloxetine in reducing pain in older adults with knee OA. 288 patients aged 65 years and above with ACR clinical and radiographic criteria of primary knee OA attending the outpatient clinic of our institution were enrolled in this study. All patients underwent a physical examination and where questioned about the number of flares. Exclusion criteria included any inflammatory, autoimmune, psychiatric illness and morbid obesity. Patients were randomized 1:1. One hundred and forty four received 60mg/day of duloxetine HCL and 144 received placebo together with their usual therapy for 16 weeks. The primary outcome measure was pain reduction. Secondary outcome measures included improvements in physical functioning scores. Pain was assessed using the Brief Pain Inventory (BPI) and Visual Analogue pain Scale, (VAS, 0-100 mm). Functional assessment using the self-reported physical function as measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), WOMAC pain and stiffness scores and the Geriatric Depression Scale (GDS) was conducted. Alterations in dosage of analgesic/NSAID drugs used were recorded. Safety and tolerability were also assessed. Data was collected at baseline and at monthly intervals for 4 months. All staff involved in data collection was blinded to the treatment assignment groups.