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We read with interest the paper regarding the efficacy and safety of strontium ranelate in the treatment of knee osteoarthritis: results of a double-blind, randomised placebo-controlled trial.1 We note the exclusion criteria included secondary knee osteoarthritis. On review of the results section, it appears that many of the patients, the randomised and the intention-to-treat groups, for example, the strontium 1 g/day group, strontium 2 g/day group and placebo group, were either overweight or obese having a raised body mass index (BMI) between 29 kg/m2 and 30 kg/m2. It is well documented in the literature that patients who are obese are more likely to have knee osteoarthritis.2 It is also included in the American College of Rheumatology (ACR) criteria as one of the most common causes of secondary osteoarthritis. Our question is whether those with a raised BMI should have been excluded from the study. Also, we do not know from the study what the patients’ mean BMI was at the start and end of the study; therefore, we cannot extrapolate as to whether a change in BMI may have influenced the results.
Also although strontium ranelate does appear to have structure-modifying activity with smaller degradations in joint space width, we note that these effects were minimal. The study suggests that 14 patients (95% CI 9 to 57) would need to be treated with 2 g strontium ranelate over the study duration to prevent one case of radiological progression ≥0.5 mm, a threshold known to predict osteoarthritis-related surgery. Therefore, although this study shows that strontium ranelate has a beneficial effect in patients with osteoarthritis, it would be interesting to see if investing in weight loss and exercise regimes would be as effective, or more effective. It has been shown that if all overweight and obese people reduced their weight by 5 kg or until their BMI was within the recommended normal range, 24% of surgical cases of knee osteoarthritis might be avoided. (95% CI 19% to 27%).3 A study looking at radiological joint space width in patients with raised BMI post weight loss and exercise regime would be of great interest.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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