Construction of multiple and mixed valvular heart disease-related age-adjusted comorbidity index and its predictive value for patient prognosis.

Abstract

Objectives: To create a multiple and mixed valvular heart disease (MVHD)-related age-adjusted comorbidity index (MVACI) for predicting mortality risk of patients with MVHD.

Methods: A total of 4080 patients with moderate or severe MVHD in the China-VHD study were included. The primary endpoint was 2-year all-cause mortality. A MVACI prediction model was constructed based on the mortality risk factors identified by univariate and multivariate Cox regression analysis. Restricted cubic spline curves were plotted to assess the relationship between MVACI scores and 2-year all-cause mortality. The optimal threshold, determined by the maximum Youden index from receiver operator characteristic (ROC) curve analysis, was used to stratify patients. Kaplan-Meier method was used to calculate 2-year all-cause mortality and compared using the Log-rank test. Univariate and multivariate Cox proportional hazards models were employed to calculate hazard ratios (HR) and 95% confidence intervals (CI), evaluating the association between MVACI scores and mortality. Paired ROC curves were used to compare the discriminative ability of MVACI scores with the European System for Cardiac Operative Risk Evaluation Ⅱ(EuroSCORE Ⅱ) or the age-adjusted Charlson comorbidity index (ACCI) in predicting 2-year clinical outcomes, while calibration curves assessed the calibration of these models. Internal validation was performed using the Bootstrap method. Subgroup analyses were conducted based on etiology, treatment strategies, and MVHD staging.

Results: Multivariate analysis identified the following comorbid conditions and age as variables independently associated with 2-year all-cause mortality in patients: pulmonary hypertension, myocardiopathy, heart failure, low body weight (body mass index<18.5 kg/m²), anaemia, hypoalbuminemia, renal insufficiency, cancer, New York Heart Association (NYHA) functional class and age. The score exhibited good discrimination (AUC=0.777, 95%CI: 0.755-0.799) and calibration (Brier score was 0.062), with significantly better predictive performance than the EuroSCORE Ⅱ or ACCI (both adjusted P<0.01). The internal validation AUC for the 2-year mortality of the MVACI model was 0.777. MVACI scores, as a continuous variable (adjusted HR=1.226, 95%CI: 1.195-1.258, P<0.01) or categorized using thresholds determined by the Yoden index (MVACI≥8 vs MVACI<8: adjusted HR=3.429, 95%CI: 2.718-4.327, P<0.01), were independently associated with 2-year mortality. The prognostic value of the score remained consistent in patients regardless of their etiology, therapeutic option, and stage of MVHD.

Conclusions: The MVACI was constructed in this study based on age and comorbidities, which can be used for mortality risk prediction and risk stratification of MVHD patients. It's a simple algorithmic index and easy to use.