Background/Purpose: Clinical trials demonstrate that diclofenac sodium gel 1% (DSG 1%), a topical NSAID, provides significantly better pain relief than vehicle placebo for patients with osteoarthritis (OA) of the knee. As patient BMI may affect the systemic availability and the volume of distribution of topical therapeutics, a post-hoc analysis was conducted to determine whether BMI has any clinical impact on the efficacy of DSG 1% in patients with OA of the knee.

Methods: This analysis pooled data from 3 vehicle-controlled studies of DSG 1%, VOSG-PN-304, VOSG-PN-310 and VOSG-PN-316, all double-blind studies with similar design and efficacy end-points, including Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) pain, function, and stiffness and pain on movement (POM). Efficacy data were analyzed as change from baseline and stratified by 3 BMI groups, (< 25, ≥25 to < 30, ≥30 kg/m2) at each visit (1, 4, 8 and 12 weeks). Populations included the Intention to Treat (ITT) efficacy population (all patients randomized and treated), and the Modified Efficacy Subset (MES) (patients with no decline in POM score between the screening and baseline visits and a score of 0-1 on the WOMAC abridged pain index for the contralateral knee). The treatment by BMI interaction from an analysis of covariance model was used for assessment.

Results: Improvement from baseline was larger for DSG 1% compared to vehicle in all 3 BMI groups for all 4 efficacy measures at each time point in both the ITT and MES populations. There were no significant differences in treatment effects between the 3 BMI groups at any time point for all 4 efficacy measures for both the ITT and MES population. Mean treatment effect (DSG 1% minus vehicle) at Week 12 and P-value for difference between < 25 (n=203), ≥25 to < 30 (n=460), ≥30 (n=751) kg/m2 BMI groups, respectively were: WOMAC pain, 1.01, 0.87, 0.79 (P=.94); POM, 9.66, 7.13, 6.06 (P=.71); WOMAC function, 2.38, 2.97, 3.77 (P=.78); WOMAC stiffness, 0.30, 0.47, 0.45 (P=.84) in the ITT population and WOMAC pain, 0.75, 1.48, 1.23 (P=.69); POM, 8.80, 10.39, 8.79 (P=.91); WOMAC function, 1.78, 4.99, 5.30 (P=.40); WOMAC stiffness, 0.22, 0.68, 0.66 (P=.37) in the MES population.

Conclusion: In this pooled analysis, patients treated with DSG 1% showed larger improvement from baseline in all 3 BMI groups, for all 4 efficacy measures, and at each time point compared to vehicle. There were no significant differences in efficacy between the 3 BMI groups, indicating that DSG 1% is efficacious regardless of BMI in patients with OA of the knee and that dose adjustments based on body size are not necessary.

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/bmi-has-minimal-effect-on-reduction-of-symptoms-in-patients-with-osteoarthritis-of-the-knee-treated-with-diclofenac-1-gel/