Response to: Important Considerations When Determining the Cost-effectiveness of Viscosupplements in the Treatment of Knee Osteoarthritis

We appreciate the feedback provided, and would like to address the highlighted concerns. The authors suggest that the included studies represent a small sample of the available literature. The studies included in our review were selected in a systematic and unbiased manner using comprehensive search of the published literature and pre-defined eligibility criteria. We do acknowledge that this economic analysis, like many others, is limited by the available data [1–4]. Many cost-effectiveness analyses use data from a single primary investigation, or combine cost an efficacy data from several identified studies, which is similar to our approach [2, 4–6]. As suggested by the authors, we accounted for the number of injections in our costing of each product. Despite this, the assumption that the authors of the editorial have made in their calculations assumes that all products have comparable efficacy, which is not accurate. Cost-effectiveness analyses consider differences in both cost and effectiveness. Assuming that the effectiveness is comparable is a cost-minimalization analysis, which is not appropriate when there are differences in both cost and effectiveness among the therapies compared. Utility scores derived from our included studies [7–11], as well as recent meta-analyses [12, 13], demonstrate considerable differences in efficacy that have been suggested to be due to product characteristic differences, such as molecular weight and production process. For this reason, we do not believe the authors’ calculations looking strictly at product costs is J. Rosen (&) Department of Orthopaedics and Rehabilitation, New York Presbyterian Queens, New York, USA e-mail: [email protected]