CORR Insights®: Kaplan-Meier Survival Analysis Overestimates the Risk of Revision Arthroplasty: A Meta-analysis

Abstract

I t is well known that the KaplanMeier estimator overestimates the probability of events of interest in the presence of competing risks [1, 8]. For example, if a study seeks to examine the durability of a particular arthroplasty implant (so the event of interest is revision), and a substantial proportion of the patients die, the Kaplan-Meier approach will overestimate the frequency of revision, since patients who have died cannot subsequently undergo revision. As such, death is considered a competing event to the event of interest (implant revision). The more frequent the competing events, the more KaplanMeier-based estimates will depart from the true probability of occurrence of the event of interest. In light of this, alternative analytic approaches that account for the occurrence of such competing events have been developed to estimate the cumulative incidence [1, 8]. While these issues are mathematically demonstrated and have been illustrated in various medical domains [2, 3, 6], they have received less attention in orthopaedic research until recently [7, 8]. But while some work has been done in individual datasets [8], to my knowledge, no study has taken a broader look at the influence of the phenomenon of competing risks on Kaplan-Meier survivorship estimates across orthopaedics more generally. In their study, Lacny et al. [4] adopted a meta-epidemiological approach to quantify the overestimation of the probability of revision by Kaplan-Meier estimator. They performed a systematic review and included studies that presented the probability of revision after hip or knee arthroplasty using both KaplanMeier and competing risks methods. Results showed that using KaplanMeier estimator overestimated the probability of revision by 7% in the strata with highest number of revision, and by 55% in those with highest proportion of patients who died during followup, which is a substantial difference indeed. While the study failed to demonstrate the effect of a higher proportion of competing events (deaths) on the overestimation, the data still This CORR Insights is a commentary on the article ‘‘Kaplan-Meier Survival Analysis Overestimates the Risk of Revision Arthroplasty: A Meta-analysis’’ by Lacny and colleagues available at: DOI: 10.1007/ s11999-015-4235-8. 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/s11999-0154235-8. R. Porcher PhD (&) Center of Clinical Epidemiology, Hopital Hotel-Dieu, 1 Parvis NotreDame Place Jean-Paul II, 75004 Paris, France e-mail: raphael.porcher@htd.aphp.fr CORR Insights Published online: 11 April 2015 The Association of Bone and Joint Surgeons1 2015