Conflict of interest in the assessment of hyaluronic acid injections for osteoarthritis of the knee: an updated systematic review.

The search results of a recent systematic review of prospective, randomized, placebo-controlled trials on hyaluronic acid injections for knee arthritis were updated and reviewed for funding source and qualitative conclusions. Forty-eight studies were identified; 30 (62.5%) were industry funded, and 3 (6.25%) were not. Fifteen (31.3%) studies did not identify a funding source. An association was observed between a reported potential financial conflict of interest of the author and the qualitative conclusion (P=0.018). None of the studies with a reported financial conflict of interest of at least one author had an unfavorable conclusion; 11 (35%) of the 31 studies with no industry-affiliated authors indicated that hyaluronic acid injection for knee osteoarthritis was no more effective than a placebo injection.