Friday, February 7, 2014

Hyaluronic acid injection for Knee Osteoarthritis

Rheumatology News has an article on a study telling us “Hyaluronic acid injection for knee OA as effective as NSAIDs in short term” (Links are listed below).
The study is from Japan. It’s a multicenter, randomized, open-label, parallel-group, non-inferiority comparison study. One group received a weekly injection injection into the (one?) knee for five weeks and the other group received three times 60 mg of loxoprofen, which is an NSAID of the same group like ketoprofen or ibuprofen. Loxoprofen is only available in Japan, Mexico, Brazil, Argentina, and India. The primary endpoint was the percentage change in the patient-oriented outcome measure for knee OA, the Japanese Knee Osteoarthritis Measure (JKOM) score. Rheumatology News tells about the secondary endpoint: “and their percent change from baseline in pain as rated on a 0- to 100-point visual analog scale (VAS, secondary endpoint).”
Results: "The difference in the percentage changes of the JKOM score between the two intervention arms (IA-HA; - 34.7 % (P < 0.001), NSAID; - 32.2 % (P < 0.001)) was - 2.5 % (95 % confidence interval (CI): - 14.0 to 9.1), indicating IA-HA was not inferior to NSAID. The frequency of both withdrawal and adverse events in the IA-HA group were significantly lower than those in the NSAID group (P < 0.026 and 0.004, respectively)."
The study tells us, that after five weeks of treatment the effects of hyaluronic acid injection for knee OA is equal to an NSAID. How about the first two weeks? Is hyaluronic acid working or the injection itself? Invasive manipulations have a high percentage of placebo effect, but we do not have a placebo control group. We don’t even know if the control group is disappointed not getting their injections and therefore have less pain relief. Withdrawal in the NSAID group had been higher, but the use of gastro protective agents has only been allowed and not been mandatory.
The study has been perfectly done, but it fails to prove that hyaluronic acid injection for knee OA is the road to follow.

Loxoprofen on Wikipedia -

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