Bidirectional Associations Between Frailty and Preeclampsia: A Two-Sample Mendelian Randomization Study

This study aims to elucidate the potential bidirectional genetic relationship between frailty and preeclampsia (PE), which currently remains unclear.

We performed a bidirectional two-sample Mendelian randomization (MR) analysis to assess the causal link between the frailty index (FI) and PE. Summary statistics for FI were sourced from the IEU Open GWAS project (ebi-a-GCST90020053). For PE, two independent datasets were employed: one from IEU Open GWAS (ebi-a-GCST90018906) and another from the FinnGen R12 release (finn-b-O15_PREECLAMPS), to improve robustness and generalizability. The primary analysis used the inverse variance weighted (IVW) method, supported by MR-Egger, weighted median, simple mode and weighted mode methods. Sensitivity analyses were performed using Cochrane's Q test, the MR-Egger intercept test, the MR-PRESSO global test and leave-one-out analysis.

Genetically predicted FI conferred an increased odds of PE, as robustly demonstrated by the IVW method in both independent datasets: ebi-a-GCST90018906 (OR = 3.027, 95% CI [1.445, 6.343], P = 0.003]) and finn-b-O15_PREECLAMPS (OR = 1.561, 95% CI [1.013, 2.404], P = 0.043). Conversely, PE also showed a significant causal effect on FI in the FinnGen dataset (OR = 1.047, 95% CI [1.031, 1.064], P < 0.001). These results indicate that higher genetically predicted frailty is a risk factor for PE and PE may in turn contribute to the exacerbation of frailty. The robustness of these associations was supported by consistent findings across multiple sensitivity analyses.

This study provides suggestive genetic evidence for a potential bidirectional relationship between frailty and PE. The forward-direction findings, with frailty as the exposure and PE as the outcome, were consistently supported across two independent datasets, while the reverse-direction findings, with PE as the exposure and frailty as the outcome, were dataset-dependent and require further validation. Frailty may represent a promising target for obstetric risk stratification, pending confirmation in pregnant populations.