Association Between Stress Hyperglycemia Ratio Index and All-cause Mortality in Critically Ill Patients with Atrial Fibrillation: a Retrospective Study Using the MIMIC-IV Database

Background: The stress hyperglycemia ratio (SHR) was developed to mitigate the influence of long-term chronic glycemic factors on stress hyperglycemia levels, which are associated with adverse clinical events, particularly cardiovascular events. However, studies examining the SHR index and its prognostic significance in patients with atrial fibrillation (AF) are lacking. This study aims to evaluate the relationship between the SHR index and all-cause mortality in critically ill patients with AF upon Intensive Care Unit admission.

Methods: The patients' data were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. All patients were categorized into four groups based on the SHR index. The outcomes include both primary and secondary endpoints, with the primary endpoints being 30-day and 365-day all-cause mortality, and the secondary endpoints being 90-day and 180-day all-cause mortality. The SHR index was analyzed using quartiles, and the Kaplan-Meier curve was employed to compare the outcomes across groups. Cox proportional-hazards regression and restricted cubic splines (RCS) were used to assess the relationship between the SHR index and the outcomes.

Results: Out of a total of 1,685 participants, the average age was 63.12 years (range: 40.17 to 101.49), with 1,004 (59.58%) being male. Higher levels of the SHR index were associated with an increased risk of all-cause mortality at 30 days, 90 days, 180 days, and 365 days, as indicated by the Kaplan-Meier curves (log-rank P < 0.01). Additionally, Cox proportional-hazards regression analysis revealed that the risk of mortality at these time points was significantly higher in the highest quartile of the SHR index. Restricted cubic splines (RCS) analysis demonstrated U-shaped relationships between the SHR index and all-cause mortality, with inflection points at 0.73 for 30-day mortality and 0.76 for 365-day mortality. Compared to patients with SHR levels below these inflection points, those with higher levels had a 69.9% increased risk for 30-day all-cause mortality (hazard ratio [HR] 1.699; 95% confidence interval [CI] 1.336 to 2.159) and a 61.6% increased risk for 365-day all-cause mortality (HR 1.616; 95% CI 1.345 to 1.942).

Conclusion: In critically ill patients with AF, higher levels of the SHR index are significantly associated with an increased risk of all-cause mortality at 30 days, 90 days, 180 days, and 365 days. The SHR index may serve as a valid indicator for assessing the severity and guiding the treatment of AF patients in the ICU.