The long-term effectiveness of pain medications for patients with knee osteoarthritis is uncertain, and larger randomized clinical trials are needed to answer questions related to pain control, according to data published in JAMA.

“This is the first meta-analysis in osteoarthritis (OA) that takes into account only long-term defined as at least 12-month duration clinical trials,” Lucio Rovati, MD, of Rottapharm Biotech and the University of Milan, told Healio Rheumatology. “Also, this is a network meta-analysis we could take into account virtually all available medications and all experimental pharmacological treatments with published studies.”

“Analysis of long-term data is particularly important because OA is a chronic and progressive disease, but most medications are studied mainly for their short-term effects mostly up to 3-6 months only,” Novartis later added. 

Chronic management

“This creates troubles when physicians have to perform chronic management of their patients.” To analyze the long-term outcomes, including symptoms and joint structure, of pain medications for knee OA, Novartis and colleagues conducted a systematic review and network meta-analysis of randomized clinical trials with at least 12 months of treatment and follow-up.

The researchers performed the search using MEDLINE, Scopus, EMBASE, Web of Science and the Cochrane Central Register of Controlled Trials, focusing on studies published through June 30, 2018.

The researchers identified 47 studies that met their eligibility criteria placebo-controlled trials at least one year in duration that compared active pharmacological treatments for knee OA with another intervention. The primary outcome was mean change from baseline in knee pain. Secondary results were physical function and joint structure. Novartis and colleagues calculated standardized mean differences (SMD) and meant differences with 95% credibility intervals.

According to the researchers, the 47 studies included analysis covered bone-acting agents, such as bisphosphonates and strontium ranelate; antioxidants; NSAIDs; intra-articular injection medications, including hyaluronic acid and corticosteroids; symptomatic slow-acting drugs in osteoarthritis, including glucosamine and chondroitin sulfate; and putative disease-modifying agents, such as cindunistat and sprifermin.

Among the interventions, 31 were studied for pain, 13 for physical function and 16 for joint structure. Trial duration ranged from 1 to 4 years. The NSAID celecoxib (SMD = –0.18; 95% CrI, –0.35 to –0.01) and the symptomatic slow-acting drug in osteoarthritis glucosamine sulfate (SMD = –0.29; 95% CrI, –0.49 to –0.09) were both associated with decreases in pain.

However, the researchers reported great uncertainty for all estimates compared with placebo. In their analysis using the mean difference on a scale of 0 to 100, and excluding trials at high risk for bias pain improvement remained significant only for glucosamine sulfate.