The albumin-bilirubin score predicts severity and long-term outcomes in patients with chronic thromboembolic pulmonary hypertension

Background & Aims We aimed to evaluate the albumin-bilirubin (ALBI) score as a measure of cardio-hepatic interactions in relation to long-term mortality in chronic thromboembolic pulmonary hypertension (CTEPH). Methods Our study group comprised 235 patients (51.1% female, mean age: 62.5±15.4 years) diagnosed with CTEPH at our hospital between January 2010 and December 2024, regardless of the selected treatment method. The diagnosis of CTEPH was made according to the definitive criteria of the ESC/ERS 2015 and 2022 Pulmonary Hypertension guidelines, depending on the time of first hemodynamic confirmation. Multiparametric risk assessment tools included the ESC/ERS 2022, COMPERA 3-strata, REVEAL 2.0, REVEAL Lite 2.0, and four-component French Registry risk scores at baseline evaluation. The ALBI score was calculated based on serum albumin and total bilirubin levels using the following formula: ALBI = (log10 bilirubin [μmol/L] × 0.66) + (albumin [g/L] × −0.085). Results Patients were divided into two groups according to a cut-off value of -2.6, with low and high ALBI scores defined as ≤ -2.6 and > -2.6, respectively. A high ALBI score, compared to a low ALBI score, was associated with a shorter six-minute walk distance (162.1±134.1 vs. 233.6±145.7, p<0.001), a higher frequency of WHO functional class III/IV status, higher NT-ProBNP levels (4626.2±6785.6 vs. 2426.2±4051.9, p=0.003), and lower aortic and mixed venous oxygen saturations (89.9±7.3% vs. 92.2±4.8%, p=0.005 and 58.4±10.3% vs. 62.5±8.2%, p<0.001) at baseline assessment. The high ALBI group was more likely to be classified as intermediate- or high-risk according to the ESC/ERS 2022 baseline risk score, COMPERA 3-strata, REVEAL 2.0, REVEAL Lite 2.0, and the four-component French Registry score at baseline evaluation. The median and mean follow-up durations were 313 days (IQR: 68.5-863) and 560 ± 631 days, respectively. The low ALBI group had significantly higher Kaplan-Meier survival estimates at 1 year (93.3% vs. 70.3%), 3 years (93.3% vs. 71.8%), and 5 years (93.3% vs. 34%). Conclusions The ALBI score at the time of diagnosis appears to be associated with clinical, neurohormonal, and hemodynamic markers of disease severity, risk status as assessed by multiparametric scoring models, and long-term outcomes in patients with CTEPH.