CORR Insights(®): There Are No Differences in Short- to Mid-term Survivorship Among Total Hip-bearing Surface Options: A Network Meta-analysis.

Abstract

I n their article, Wyles et al. have compared different THA bearing surfaces in terms of probability of revision using network meta-analysis (NMA) [5]. NMA is appealing because it allows the comparison of multiple healthcare interventions for a given condition—even when no direct comparisons (head-to-head trials) exist between some of those interventions—by combining the direct evidence with indirect evidence across randomized trials using the same comparator. Because of its appeals, NMA is gaining traction; however, NMA remains a relatively new approach, and the papers using it suffer from inconsistent terminology and heterogeneous reporting [1]. Many researchers and surgeons may be unfamiliar with NMA, and its related concepts and assumptions. Crucial assumptions relate to homogeneity among individual trials involving the same comparison, as in classical meta-analysis, but homogeneity also comes into play in NMA where indirect evidence is concerned. Indirect evidence refers to the results arising from the network—the ‘‘N’’ in ‘‘NMA’’—that allows the comparison of two treatments even when they have not been evaluated directly against one another in head-to-head trials. For example, in a NMA involving treatments A, B, and C, direct evidence for the comparison of treatment A to treatment C refers to trials which compared A to C, and indirect evidence refers to information that can be deduced from trials comparing treatments A to B, and treatments B to C. Issues pertaining to indirect evidence involve both statistical and conceptual aspects. For instance, transitivity implies that there are no differences in treatment-effect modifiers among studies, which may have affected the direct treatment effect estimates used to derive the indirect evidence for a comparison. The related statistical aspect is consistency or coherence, which implies that the direct and indirect treatment This CORR Insights is a commentary on the article ‘‘There Are No Differences in Shortto Mid-term Survivorship Among Total Hipbearing Surface Options: A Network Metaanalysis’’ by Wyles and colleagues available at: DOI: 10.1007/s11999-014-4065. The author certifies that he, or any member of his immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/ licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or the Association of Bone and Joint Surgeons. This CORR Insights comment refers to the article available at DOI: 10.1007/s11999014-4065. R. Porcher PhD (&) Center of Clinical Epidemiology, Hopital Hotel-Dieu, 1 Parvis Notre-Dame Place Jean-Paul II, 75004 Paris, France e-mail: raphael.porcher@htd.aphp.fr CORR Insights Published online: 23 January 2015 The Association of Bone and Joint Surgeons1 2015