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28-08-2018 | Rheumatology | News | Article

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Oral OA therapy not linked to knee replacement risk

medwireNews: Exposure to oral osteoarthritis (OA) therapies is unlikely to be a risk factor for requiring knee replacement, suggests an analysis of the Osteoarthritis Initiative database.

In recent years, “[c]oncerns have […] been raised about the effects of these drug treatments on the evolution of OA structural changes, particularly in weight-bearing joints such as the hip and knee,” and the impact of oral treatment on OA progression “remains at this time an open question,” say the researchers.

The study involved 218 OA patients who underwent a knee replacement procedure between 2004 and 2015, and 540 control OA patients with no history of knee replacement matched for age, sex, income, Kellgren–Lawrence grade, Western Ontario and McMaster Universities Osteoarthritis Index pain score, and duration of follow-up.

The most commonly used oral OA therapies were nonsteroidal anti-inflammatory drugs (NSAIDs) in the knee replacement and control groups, with 38.5% and 33.3% of patients, respectively, reporting their use at 1–79% of consultations over the past 3 years, and a corresponding 24.2% and 15.3% reporting their use on at least 80% of visits. Other oral treatments used by study participants were acetaminophen, glucosamine/chondroitin sulfate, narcotics, and cyclooxygenase-2 inhibitors.

Jean-Pierre Pelletier (University of Montreal Hospital Research Centre, Québec, Canada) and colleagues found no significant association between exposure to any oral OA therapy within the past 3 years and the occurrence of knee replacement after controlling for potential confounders such as demographics, symptom severity, and radiographic grading.

Similarly, there was no significant association between exposure to these therapies for 2, 4, or 5 years and knee replacement rates, report the study authors in Arthritis Research & Therapy.

However, a number of baseline clinical and sociodemographic factors were significantly associated with subsequent knee replacement risk, including White race, BMI of at least 27 kg/m2, and higher Knee injury and Osteoarthritis Outcome Scores.

“In an era of OA therapeutic choice paucity, our study is somewhat reassuring,” say Pelletier and team. They say that their findings “tackle the confounding role of any oral intervention to treat pain as a ‘last resort’ prior to inevitable surgery, creating a spurious association between drug usage and the risk of [knee replacement], in turn suggesting a deleterious role of the medication via a channeling bias.”

The study authors caution that their study did not include information about specific drugs within the classes studied, and that unmeasured confounders may have influenced their results. Furthermore, “this study focused on patients with severe OA in need of surgery,” and the results may not be applicable to patients with less severe disease, they add.

By Claire Barnard

medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group