Background/Purpose: In a large, randomised, placebo-controlled, double-blind phase-III 3-year study (SEKOIA), strontium ranelate 2g/day (SrRan) has demonstrated structure-modifying activity associated with statistically significant symptomatic improvement in patients with knee OA. In clinical trials, results for symptom improvement are usually reported as mean change in score which may not be directly clinically meaningful. The objective of this analysis was to describe, at an individual level, the effects of strontium ranelate on pain in patients with knee OA compared to placebo.

Methods:  The main objective of the SEKOIA study was to demonstrate the effects of strontium ranelate on radiographic progression of knee osteoarthritis. Included patients were men and women over 50 years old, with symptomatic primary knee OA (at least 40 on a 100 mm visual analog scale (VAS) on most days of the previous month i.e. 1/2 days, Kellgren and Lawrence [KL] grade 2 or 3, and joint space width [JSW] 2.5–5 mm). Symptoms were assessed every 6 months over 3 years using the WOMAC questionnaire and a 100 mm VAS (“How would you rate the pain you have felt in the studied knee within the last 48 hours?”). Proportions of patients with an improvement of at least 20% or 50% from baseline of their WOMAC pain subscore⁽¹⁾ or pain VAS and proportion of OMERACT-OARSI-like responders⁽²⁾ (calculated using improvement in pain and function but not patient’s global assessment as it was not assessed in this study) were compared using a chi² test.

Results: The ITT population included 1371 (82%) patients. At baseline, the mean, age was 63±7 years, BMI was 30±5 kg/m², VAS was 54±22 mm, and WOMAC was 132±62 mm. 61% were KL grade II and 69% were female. There were no differences between groups at baseline. Over 3 years, a significantly greater percentage of strontium ranelate 2g-treated patients had 20% improvement in WOMAC pain compared with placebo (72% vs 64%, p= 0.010) and a trend was seen with 50% improvement (51% vs 45%, p = 0.078). Similar results were confirmed on the VAS, with a greater number of patients having an improvement in global knee pain of at least 20% (76% vs 70%, p = 0.034) or at least 50% (60% vs 53%, p = 0.065) compared to placebo. When combining improvement in pain with improvement in function (OMERACT-OARSI-like responders) the percentage of responders was significantly greater in the strontium ranelate 2g group (54% vs 47%, p = 0.035) than in the placebo group.

Conclusion: Strontium ranelate 2g/day is associated with a greater number of patients having a clinically relevant decrease in their pain level over 3 years compared to placebo-treated patients. Strontium ranelate treated patients were also more likely to be OMERACT-OARSI-like responders.

References

1-Bellamy et al. AnnRheum Dis 2005; 64:881-885

2-Pham et al. Osteoarthritis and Cartilage (2004). 12:389-399

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