Strontium ranelate significantly decreases radiological progression using a new definition for radiological progression in patients with primary knee osteoarthritis treated with strontium ranelate

Background/Purpose: Strontium ranelate (SrRan) 2g/day  has demonstrated a structure-modifying activity associated with symptoms improvement in patients with knee OA in a large, randomised, placebo-controlled, double-blind phase-III 3-year study. The objective of a planned analysis was to describe the efficacy of SrRan on radiological progression with a new definition of radiological progressing patients. This definition is based on an algorithm which aimed to ensure the robustness of the changes in JSW taking into account JSW change consistency over time. These radiological progressing patients have been demonstrated to be at higher risk of knee surgery¹.

Methods: 1683 patients with symptomatic primary knee OA (ACR criteria) were included and randomly assigned to SrRan 1g, 2g or placebo for 3 years. Percentage of radiological progressors between baseline and last observation were compared across groups in the intention to treat and per protocol populations using a chi-square test. A logistic model with adjustment on risk factors (age, BMI and Kellgren-Lawrence grade) was also carried out. Radiological progressors were defined as described below (exploratory method):

Results: The ITT set included 1371 (82% of the randomised set) patients. Age was 63±7 years, BMI was 30±5 kg/m², JSW was 3.5±0.8 mm. 61% were KL II. 69% were female. There were significantly fewer radiological progressors between baseline and last observation in the SrRan groups than in the placebo group: 23.8% (p<0.001), 25.3% (p<0.001) in the SrRan 1g and 2g groups respectively compared to the placebo group (41.7%%). The RRR (and NNT) compared to placebo were 42.9% (NNT=6) and 39.3% (NNT=7) in the 1g and 2g group, respectively. Results are confirmed on the per protocol population (N=865): 26.4% (p<0.001); 27.6% (p<0.001) in the SrRan 1g and 2g compared to 49.0% in the placebo group. After adjustment on confounding factors results are similar.

Conclusion: Strontium ranelate 1 and 2g/day significantly reduce the number of knee OA patients with a significant radiological progression suggesting a long-term beneficial effect on knee OA-related surgery.

  References

1 Bruyere et al, 2012. Prediction of knee surgery in patients with osteoarthritis by the use of a new definition of X-ray progression. 2012.Ost Int.23 (suppl2). S363.