This multi-author study was designed to compare in patients with knee osteoarthritis (OA) a product called Cingal - a mix of a hyaluronic acid (HA) derivative and a steroid - with the same company's other product (Monovisc) which did not have the steroid in it and then it was also compared with injections of saline containing neither of the trial substances. Well-known scoring systems were used to evaluate any improvement or otherwise in pain and other indices of function.
The study was well-designed but there were some limitations in that it only involved 360 subjects and was discontinued at 26 weeks when it might have been helpful to have followed the patients for even longer. The study was funded by the manufacturer, but it was multicentric and fully double-blinded, which means that no-one at all knew which of the patients received which of the medications all the way through the study.
Twelve people were lost to the study, approximately the same proportion in each of the three groups, and none of these was due to a bad reaction. A further number of patients were withdrawn from the analysis because protocol had been violated, so in the end it was only 335 patients who fully participated and were fully analysed.
The patients were well assessed before and monitored during the study.
With each treatment, the existing joint fluid was fully aspirated (and sent to the laboratory) and then the test injection was given into the knee.
The improvement shown by Cingal was significantly greater than saline through 12 weeks ( P = 0.0099) and 26 weeks ( P = 0.0072) which were the two key points of reference. [The low 'P' or probability scores indicate that these findings were statistically significant.]
A low incidence of related adverse events was reported and these were much the same irrespective of the study group.