Red blood cell distribution width to serum albumin ratio index and its association with all-cause mortality in obstructive sleep apnea patients with critical illness comorbidity: A retrospective study using the MIMIC-IV database.

OBJECTIVE

To evaluate the prognostic value of Red Blood Cell Distribution Width-Albumin Ratio (RAR) in patients with obstructive sleep apnea (OSA) complicated by critical illness for all-cause mortality.

METHODS

Based on the MIMIC-IV database, 2536 OSA patients (first ICU admission) were enrolled and divided into four quartiles (Q1-Q4) according to RAR. Kaplan-Meier survival analysis, multivariate Cox regression (adjusted for age, gender, SOFA/APSIII), and subgroup analysis using restricted cubic spline (RCS) were employed to verify associations.

RESULTS

The 30-day/365-day mortality rates in Q4 group (RAR≥5.55) were significantly higher than those in Q1 group (P < 0.001). Adjusted HR for 30-day mortality in Q4 group was 2.06 (95% CI: 1.30-3.37), and 365-day HR was 2.19 (95% CI: 1.49-3.25). RCS confirmed a linear positive correlation between RAR and mortality (non-linear P > 0.05).

CONCLUSION

Elevated RAR is associated with increased all-cause mortality risks at 30,90,180, and 365 days in patients with severe OSA, serving as an independent predictor of mortality risk in this population. As a low-cost, readily available biomarker based on routine blood tests, RAR can provide a reference for risk stratification in ICU patients with severe OSA.