Evaluating the efficacy of duloxetine and gabapentin in pain reduction in patients with knee osteoarthritis

In this study, we aim to compare the efficacy of Gabapentine compared to duloxetine in pain reduction and improvement of quality of life in patients with knee osteoarthritis.

In this research, 150 patients with moderate to severe knee osteoarthritis with inclusion criteria and not having exclusion criteria referring to rheumatology clinics will be included. Patients will be randomly allocated to gabapentine, duloxetine and acetaminophen groups and each patient will be given a specific code.

After patients selection, they will be randomly allocated to mgabapentine, duloxetine and acetaminophen groups. Patients in both groups will be treated for 3 months and will be evaluated before intervention and 1 and 3 months later for pain severity according to visual analogue scale (VAS), functional status according to WOMAC questionnaire and quality of life according to SF-12 questionnaire. Patients and the person evaluating the treatment outcome will be unaware of the allocated groups.

Inclusion criteria: Knee osteoarthritis with effusion; age between 45-75 years; ability to walk; having pain score of >5 according to VAS and >48 according to WOMAC questionnaire; Exclusion criteria: Other knee disorders; concomitant hip and ankle osteoarthritis; bursitis and perarticular disease; radicular pains; physiotherapy or intraarticular injection during the past 6 months; psychological disease; history of knee surgery; inflammatory joint disease; rheumatoid arthritis; fibromyalgia; active or recurrent pseudogoat; malignancy; systemic diseases including renal of hepatic failure, uncontrolled blood pressure, diabetes mellitus; asthma in need of corticosteroids; corticosteroid use in less than 5 weeks prior to study

In dulexetine group, treatment will began with 30 mg daily and will increase to 60 mg daily. In Gabapentine group, treatment will began with 300 mg daily and will increase to 600 mg daily. The third group will receive acetaminophen 1000 mg daily which could be increased to 2000 mg daily.

The main outcomes of the study are evaluating patients functional status using WOMAC (Western Ontario and McMaster Universities Osteoarthritis), pain severity using visual analogue scale and quality of life using SF-12 quality of life questionnaire which will be evaluated before intervention and 1 and 3 months after intervention.

Patients will be randomized into three groups using random number blocks and using sealed envelopes.

Patients and the person evaluating the treatment outcome will be blinded to the allocated groups.