Association of serum total bilirubin and potential predictors with mortality in acute respiratory failure: A retrospective cohort study

Background: Total serum bilirubin (TBIL) levels are a risk factor in critically ill patients. However, the relationship between the dynamics of TBIL and the prognosis of acute respiratory failure (ARF) patients is unclear.

Objectives: This study aimed to investigate the impact of different levels of TBIL during hospitalization on mortality in ARF patients.

Methods: This study used a retrospective cohort study. We extracted information on ARF patients from the Medical Information Bank for Intensive Care (MIMIC)-III (version 1.4). We used propensity score matching (PSM) to adjust for the level of potential baseline-level differences between groups. Cox regression was used to analyze mortality risk factors in patients with ARF. Subgroup analysis was used to explore special populations.

Results: 2673 patients were included in the study, and 19.7% developed hyperbilirubinemia (TBIL ≥ 2 mg/dL) during their hospitalization. After PSM, multivariate Cox regression showed a 50% and 135% increased risk of death for a maximum value of TBIL ≥ 5 mg/dL and minimum value of TBIL ≥ 2 mg/dL during hospitalization, respectively, compared to the control population. In addition, age ≥ 65 years, previous comorbid malignancies, respiratory rate ≥ 22 beats/min, SpO2 ≥ 95, BUN ≥ 20 mg/dL, lactate ≥ 5 mmol/L, platelet < 100 * 10 ^ 9/L were independent risk factors for 1-year mortality in ARF patients. Subgroup analysis showed that high bilirubin had a greater effect on patients aged less than 65 years (P for interaction < 0.05).

Conclusions: Hyper TBIL (TBIL max ≥ 5 mg/dL or TBIL min ≥ 2 mg/dL) was an independent risk factor for 1-year mortality in patients with ARF. This study suggests that clinicians should be aware of TBIL levels and intervene early in these patients.