The 5-Item Modified Frailty Index (mFI-5) for risk stratification of patients with infective endocarditis undergoing cardiac surgery

Abstract Background population aging has led to an increased burden of frailty as an emerging global health issue, and variables for its quantification in patients with infective endocarditis (IE) are lacking in current surgical risks scores. The 5-item modified frailty index (mFI-5) score has shown to be effective in the prediction of surgical outcomes in other medical scenarios. Purpose this study aimed to assess the role of the mFI-5 in the prediction of surgical outcomes in patients with left-sided IE undergoing cardiac surgery. Methods a total of 112 cases of confirmed left-sided IE undergoing surgery, were consecutively collected and followed during one year after diagnosis in two tertiary hospitals between 2016 and 2021. The mFI-5 score included 5 baseline patient-specific comorbidities: diabetes, congestive heart failure, non-independent functional status (Barthel index <80), hypertension and chronic obstructive pulmonary disease (range 0-5), and patients were categorised as mFI-low (<2, n=65), and mFI-high (>=2, n=47). Results mean age was 66 [SD 15] years, 67% were men and community-acquired infections were 75%. As shown in Table 1, mFI-high patients were older and, aside from the specific comorbidities included in the score, with more chronic kidney disease. The most isolated pathogen was S. viridans (n=32), predominantly in mFI-low, in contrast to enterococcal and polymicrobial IEs, which were more frequent in mFI-high. Larger vegetations were reported in mFI-high [16 (10) vs 13 (9) mm, p 0.03], with no differences regarding infection site or periannular complications. Acute kidney injury, decompensated heart failure and higher natriuretic peptides were more common in mFI-high. Regarding mortality, in-hospital deaths were more frequent in mFI-high group. When analyzing mFI-score as a discrete variable, in-hospital mortality was associated with higher median scores values [2 (2) vs 1(1) points, p 0.02], being 2 points the optimal cutoff point for prediction [AUC 0.64 (95% CI 0.54-0.73), Fig.1A]. Among survivors who completed follow-up (n=82), rehospitalization and all-cause mortality rates in mFI-high exceeded those from mFI-low. Predictors of in-hospital and 1-year mortality were assessed by logistic regression (Fig. 1B), confirming the independent prognostic association of mFI-5-score in patients with IE undergoing surgery. Conclusions patients with IE undergoing cardiac surgery with higher mFI-5 scores were older, more predisposed to enterococcal and polymicrobial infections, and had a greater comorbidity burden with a more complicated clinical course. The mFI-score was independently associated with in-hospital mortality as well as rehospitalizations and 1-year mortality, positioning itself as an additional tool for risk stratification in this cluster of patients.Table 1Figure 1