Pulmonary Regurgitation in Heart Failure: Causality or a Marker of Disease Severity?

1. Severe Group Imbalance and Statistical Power

The striking disparity in group sizes—272 (No PR) and 162 (Mild PR) versus only 20 (Moderate PR) and 36 (Severe PR)—raises serious concerns about the statistical power of the multivariate models. In a multivariate model featuring five predictors (PR severity, age, LVEF, PASP, and hemoglobin), the reliability of the derived coefficients for the smaller subgroups may be compromised by the lack of statistical power. This imbalance raises additional concerns regarding the precision and stability of the reported regression coefficients (β=0.48 for pro-BNP and β=−0.39 for 6MWT). We urge the authors to report 95% confidence intervals for all beta coefficients and to consider bootstrap-based sensitivity analyses to assess the robustness.

[…]