The goal of this clinical trial is to examine the effects of duloxetine on walking ability and physical activity in patients with knee osteoarthritis. Researchers will compare duloxetine to a placebo (a look-alike substance that contains no drug) to see if duloxetine works to improve walking ability in patients with knee osteoarthritis. At study visits, participants will complete surveys, perform physical function tasks, undergo non-invasive brain imaging, and undergo sensory testing.
Using a double-blind, cross-over, 16-week randomized clinical trial of duloxetine versus placebo, this study will investigate whether duloxetine improves walking ability and physical activity in knee osteoarthritis patients (N=85). Aerobic exercise such as walking is important in preventing joint deterioration and is a first-line treatment for knee osteoarthritis, despite being painful. Indeed, many patients are limited in their ability to walk due to pain. Prior literature and preliminary data from our group indicate that central nervous system (CNS) pain processing contributes to pain-related walking impairment. While acetaminophen, nonsteroidal anti-inflammatories, opioids, and surgery are often used in knee osteoarthritis, side effects and health risks limit their use in many patient subgroups. In patients with CNS changes, these treatments may be less effective. In patients with nociplastic pain related to CNS sensitization, knee replacement is associated with worse post-operative pain and functional outcomes. Potentially targeting CNS sensitization, duloxetine is the only CNS-acting medication FDA-approved for knee osteoarthritis pain, and given that patient-reported physical function improves with duloxetine, its use may slow joint degeneration and delay the need for knee replacement by improving walking ability. However, no clinical trials have investigated whether duloxetine improves objectively measured physical function. This study will address this gap and lead to future large-scale studies examining knee osteoarthritis endophenotypes, related to CNS pain processing and other pathophysiology, which may aid in identifying patients who respond better to duloxetine versus other existing therapies. Techniques used in the setting of this randomized clinical trial include patient-reported outcomes, physical performance tests, actigraphy, noninvasive brain imaging, and quantitative sensory testing.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
85
Duloxetine is an FDA-approved treatment for osteoarthritis. The drug will be prescribed for subjects with knee osteoarthritis pain to improve pain during mobility. The treatment consists of 30 mg of encapsulated duloxetine by mouth once daily for one week followed by 60 mg of encapsulated duloxetine by mouth once daily for 4 weeks. Then, patients will taper back down to 30 mg of encapsulated duloxetine by mouth once daily for one week.
The placebo is a capsule that has been filled with an inactive filler, microcrystalline cellulose (Avicel). It will match in look to the overencapsulated duloxetine capsules but not contain the duloxetine itself. Participants will take 1 week of the placebo pill identical in appearance to encapsulated duloxetine 30 mg followed by 4 weeks of the placebo pill identical in appearance to encapsulated duloxetine 60 mg. Then, patients will take one week of the placebo pill identical in appearance to encapsulated duloxetine 30 mg.
University of Pittsburgh - Center for Innovation in Pain Care (Research)
Pittsburgh, Pennsylvania, United States
Distance walked in the 6-minute walking test
Distance walked during 6 minute walking task
Time frame: 6 minutes per measurement; measured several times from enrollment to last study visit for up to 16 weeks.
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