Can’t See the Right Forest Plot for the Wrong Trees!

Abstract

We have with great interest studied the meta-analysis and forest plot in Dwyer et al. 1 which is supposed to illustrate the effect of operative versus nonoperative treatment of femoroacetabular impingement syndrome. The meta-analysis, based on three randomized controlled trials, 2-4 shows a between-group difference on the International Hip Outcome Tool-33 (iHOT-33; 0 points [worst] to 100 points [best]), favoring operative treatment (mean difference: 3.46 points; 95% confidence interval [CI] 0.07 to 6.86). We congratulate the authors on the first metaanalysis for this very important topic, but unfortunately the forest plot presented by Dwyer et al. 1 is flawed owing to incorrect use of the iHOT-33 value derived from Palmer et al., 2 published in 2019 in the

What Happens to a Published Article if a Cited Article Is Corrected?

“…In that study published in BMJ, "Arthroscopic Hip Surgery Compared With Physiotherapy and Activity Modification for the Treatment of Symptomatic Femoroacetabular Impingement: Multicentre Randomised Controlled Trial" by Palmer et al, 5 it happens that Palmer et al improperly measured and reported the International Hip Outcome Tool-33 on a visual analog scale using centimeters rather than millimeters. 2 One thing leads to another. Our award-winning researchers, Dwyer et al 3 not only cited Palmer et al 5 but quantitatively synthesized the results of the BMJ article in their meta-analysis.…”