The main risk factors leading to knee replacement surgery in patients with osteoarthritis (OA) include disease severity, symptoms, and high body mass index (BMI), but not exposure to oral OA therapy, according to the results of a nested case-control study published in Arthritis Research & Therapy.

The investigators sought to evaluate the association between exposure to commonly used oral OA treatments and relevant confounding risk factors on the incidence of knee replacement surgery using the Osteoarthritis Initiative database. Participants who underwent knee replacement surgery after cohort entry were matched with ≤4 controls for gender, age, income, Western Ontario and McMaster Universities Osteoarthritis Index pain, Kellgren-Lawrence grade, and duration of follow-up. Exposure to oral OA treatments, including acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, narcotics, and glucosamine/chondroitin sulfate within 3 years prior to the date of knee replacement surgery was determined.

Overall, a total of 218 patients who underwent knee replacement surgery were matched with 540 controls. The median time to knee replacement was 4.3 years, mean participant age was 69 years, 61% were women, and the majority of participants were Caucasian. Numerically, individuals who underwent knee replacement surgery had higher rates of exposure to acetaminophen, NSAIDs, and COX-2 inhibitors compared with controls. Exposure to glucosamine/chondroitin and narcotics was similar in both groups.

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There was no significant association demonstrated between the occurrence of knee replacement surgery and exposure to any of the oral OA treatments within the 3 years prior to the surgery. A significantly higher occurrence of knee replacement surgery was reported among Caucasian participants (odds ratio [OR], 1.84; 95% CI, 1.13-2.99; P =.015) and patients with BMI ≥27 kg/m2 (OR, 1.65; 95% CI, 1.06-2.58; P =.027).

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The investigators concluded that patients who chronically take the most commonly used oral OA therapies do not have an increased risk for undergoing knee replacement surgery. In an era in which there is a paucity of OA therapeutic choices, the results of this study are reassuring and reposition chronic OA treatment as safe. Longer-term, controlled studies and safety evaluations should also be conducted in the context of longitudinal follow-up to further explore the initial findings of this analysis.

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Dorais M, Martel-Pelletier J, Raynauld JP, Delorme P, Pelletier JP. Impact of oral osteoarthritis therapy usage among other risk factors on knee replacement: a nested case-control study using the Osteoarthritis Initiative cohort. Arthritis Res Ther. 2018;20(1):172.