Reply:

We would like to express our thanks to Maratea and colleagues for the sophisticated meta-regression analysis of our data ¹ and the discovery of the typographical error in Table 2, which has been corrected. We used inverse variance weighted one-way ANOVA, which includes numerous zeros in event frequencies. Zero frequencies are accepted in metaanalyses. Lipsey and Wilson ² recommend that research findings in the form of the proportion of a sample with a particular characteristic can be represented with the proportion as the effect size statistic with values ranging from 0.0 to 1.00. In our study, the effect size statistic was the proportion of 30-day mortality.

We are glad that the re-analysis from our Italian colleagues showed no difference in 30-day mortality between the chimney and fenestrated technique, which is in accord with our results. However, robust clinical conclusions regarding the two endovascular techniques are very difficult to determine and probably cannot be accurately drawn from any statistical comparison. The indications for chimney and fenestrated endografting are in the majority of the published cases different even if the statistical method used by Maratea and colleagues showed low heterogeneity between the two subgroups. Patients with symptomatic or ruptured aortic pathologies can be treated in the urgent setting only with chimney endografts at the moment. The inclusion of this patient population in the chimney publications may influence the mortality rate significantly; on the other hand, this cannot be illustrated with any statistical analysis. Finally, only clinical experience with chimney endografts will give the answer about the utility and durability of this promising alternative therapeutic modality.