In patients with osteoarthritis (OA) of the knee, the use of intra-articular onabotulinumtoxinA and placebo were associated with similar reductions in average daily pain score from baseline to 8 weeks and in the Western Ontario McMaster Universities Arthritis Index (WOMAC) pain score, according to the results of a multicenter, double-blind, randomized, placebo-controlled study (ClinicalTrials.gov identifier: NCT02230956) recently published in Osteoarthritis and Cartilage.
The researchers sought to assess the use of intra-articular onabotulinumtoxinA 400 U and 200 U vs an intra-articular placebo saline injection for the reduction of symptoms of knee OA among patients with nociceptive pain. Patients with knee OA and a painDETECT questionnaire score of ≤12, which is indicative of nociceptive pain, were enrolled in the study. Patients were randomly assigned to 1 of 3 treatments, including intra-articular onabotulinumtoxinA 200 U or 400 U or saline placebo. All participants were followed for 24 weeks after treatment.
The primary efficacy end point was daily average numeric rating scale pain score of the study knee over 7 days at 8 weeks. Secondary end points were WOMAC pain and physical function scores, patient global impression of change in pain score, and the 7-day average worst pain score. Adults aged 40 to 75 years with stable, painful primary idiopathic OA of the knee of ≥52 weeks duration and verified by radiologic examination <12 weeks prior to the start of the study met inclusion criteria. Among 176 enrolled patients, a total of 158 completed the study.
Daily average pain scores decreased by approximately 2 points with all treatments at 8 weeks, and the reduction was sustained throughout follow-up. No significant differences were observed between the pooled onabotulinumtoxinA groups and the placebo group (0.22; 95% CI, –0.33 to 0.76). In addition, there were no significant differences between the onabotulinumtoxinA 400 U group and the placebo group (0.42; 95% CI, –0.26 to 1.10) or between the onabotulinumtoxinA 200 U group and the placebo group (–0.03; 95% CI, –0.70 to 0.64]). There were similar results reported with all secondary efficacy measures. Treatment-related adverse events were reported in 3.4% of the pooled onabotulinumtoxinA group and placebo group, but none were deemed serious in nature.
The investigators concluded that with no significant differences reported between treatment with onabotulinumtoxinA or placebo in patients with knee OA, further research should be considered to evaluate the possible role for onabotulinumtoxinA, if any, in the management of pain associated with knee OA.
McAlindon TE, Schmidt U, Bugarin D, et al. Efficacy and safety of single-dose onabotulinumtoxinA in the treatment of symptoms of osteoarthritis of the knee: results of a placebo-controlled, double-blind study [published online May 9, 2018]. Osteoarthritis Cartilage. doi: 10.1016/j.joca.2018.05.001