Letter to the Editor: “Pre-procedural CT angiography inferior vena cava measurements: a predictor of mortality in patients undergoing transcatheter aortic valve implantation”
by Tomoyuki Kawada, MD (firstname.lastname@example.org)Pre-procedural CT angiography inferior vena cava measurements: a predictor of mortality in patients undergoing transcatheter aortic valve implantation
To the Editor,
Eberhard et al. conducted a prospective study to assess predictors of ≤ 1-year mortality in 205 patients undergoing transcatheter aortic valve implantation (TAVI) . By Cox regression analyses, hazard ratio (95% confidence interval) of supra-hepatic inferior vena cava (IVC) ≥ 665 mm2 for ≤ 1-year mortality was 5.5 (2.2-13.6), and the authors concluded that pre-procedural enlargement of the supra-hepatic IVC was recommended as a predictor of prognosis in patients with TAVI. I have two comments on this study.
First, the authors presented wide range of hazard ratio. Events per independent variable (EPV) value in Cox regression analysis should be kept ≥ 10 for keeping stable estimates of prediction [2, 3]. Namely, the requirements for unbiased estimation of regression coefficients and their standard errors have been generally described as the ‘rule of ten’. Although there are reports that this rule can be relaxed , a limited number of events might lead to misleading for the prediction of mortality. Anyway, the results for the fully adjusted models have to be interpreted with caution.
Second, Anand et al. conducted a meta-analysis to evaluate the association between frailty and mortality after TAVI . They handled past studies mainly presenting 1-year all-cause mortality. As there was a significant effect of objective assessment of frailty on 1-year mortality after TAVI, I recommend Eberhard et al. considering the level of frailty for the analysis.