Study Design
We retrospectively reviewed the patient data from consecutive aSAH patients admitted to our institution between January 2015 and September 2022. All patient data were from the Long-term Prognosis of Emergency Aneurysmal Subarachnoid Hemorrhage (LongTEAM, ClinicalTrials.gov Identifier: NCT04785976) registry. This study was approved by the institutional review board of Beijing Tiantan Hospital. Informed consent for clinical analyses was obtained from all individual participants or their authorized representatives, and all the analyses were performed in accordance with the Declaration of Helsinki and the local ethics policies. Both procedures were performed by specific senior neurosurgeons, with an annual average of more than 300 procedures per neurosurgeon. All patients were managed according to the guidelines from the American Heart Association/American Stroke Association and institutional routine.
Inclusion and Exclusion Criteria
All patients had angiographically documented aSAH confirmed by CT or lumbar puncture. In this study, the inclusion criteria were 1) age ≥ 18 years; 2) emergency admission; 3) no previous aneurysm rupture; 4) only patients treated by surgical clipping or endovascular treatment; 5) less than 72 hours from rupture to admission and less than 72 hours from admission to treatment; 6) single aneurysm; and 7) complete 90-day follow-up. Exclusion criteria were 1) other neurological diseases (tumor, vascular malformation, Parkinson's disease, multiple sclerosis, and primary epilepsy) and functional or neurological deficit of the extremities due to any cause; 2) history of neurosurgery prior to rupture; and 3) treatment, including external ventricular drainage, intubation, and/or mechanical ventilation, at other hospitals before presentation to our hospital.
Data collection
Baseline clinical characteristics and imaging data were reviewed, such as age, sex, body mass index (BMI; calculated as weight in kilograms divided by the square of the height in meters, kg/m2), location of the ruptured aneurysm, intraventricular hemorrhage, acute hydrocephalus, and medical history (e.g. hypertension, diabetes mellitus, hyperlipidemia, stroke and heart disease). The World Federation of Neurosurgical Societies (WFNS) grade, modified Fisher Scale (mFS) grade, Graeb score, Subarachnoid Hemorrhage Early Brain Edema Score (SEBES), and modified Rankin Scale (mRS) score were assessed. Postoperative clinical complications during hospitalization were collected, including rebleeding, delayed cerebral ischemia (DCI), intracranial infection, stress ulcer bleeding, abnormal hepatic function, urinary tract infection (UTI), anemia, hypoproteinemia, pneumonia, and deep vein thrombosis (DVT), electrolyte disturbance, and disorders of lipoprotein metabolism. Supplemental Table 1 shows the detailed diagnostic criteria for in-hospital complications. The mRS score and mortality rate were collected at discharge.
Exposure
Fasting blood samples were collected within 24 hour of admission and the second morning after treatment routinely. Both preoperative and postoperative serum AST and ALT were tested immediately using standard methods at the laboratory. Laboratory tests including WBC (white blood cell), total protein (TP), albumin (ALB), globulin (GLB), total bilirubine (TBIL), total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), apoprotein A1 (APO_A1), and apoprotein B (APO_B) were measured and documented. For normal tests values, please see the Supplementary Table 2.
De Ritis was calculated as AST divided by ALT. Participants were classified into four groups according to quartiles of De Ritis and two groups by the cut-off value of 1 according to previous studies. 15,16 To mitigate surgical and endovascular interference, we designated postoperative De Ritis as the exposure variable.
Outcome Assessment
The primary outcome was the mRS (a stroke outcome scale with scores ranging from 0 [no symptoms] to 6 [dead]) score at discharge and 90 days after discharge. The certified clinical research coordinators and neurosurgeons followed up with patients via telephone or an outpatient appointment 90 days after discharge. Unfavorable outcome was defined as an mRS score of 3 to 6 or 4 to 6. Second outcomes were defined as presence of prespecified in-hospital complications.
Statistical Analysis
The descriptive statistics are summarized as median (interquartile range, IQR) for continuous variables with skewed distribution and frequency (percentage) for categorical variables. After testing for normality, continuous variables were analyzed using the nonparametric Mann-Whitney U test or Kruskal-Wallis test. The Pearson chi-square test, continuity correction test, or Fisher's exact test were used to test the dichotomized and categorical independent variables.
For poor functional outcome and in-hospital complications, the logistic regression model and OR with 95% CI was used. Patients with the lowest quartile of De Ritis or De Ritis < 1 were defined as the reference group. Three adjusted models were fitted. Model 1 adjusted for age (continuous) and sex. Model 2 further adjusted for BMI, current smoker, current alcohol drinking, medical history (hypertension, diabetes mellitus, dyslipidemia, stroke, heart disease), the WFNS, mFS score at admission, location of aneurysm and treatment modality. In model 3, laboratory tests including WBC (continuous), TC, TG, HDL, and LDL were further adjusted.16 Trend tests were performed using quartiles as ordinal variables. To assess the incremental predictive value of De Ritis in addition to conventional risk factors, Delong test, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were applied. In addition, restricted cubic spline models were used to assess the dose-response relationships between De Ritis and clinical outcomes, and the knots were set at the lowest akaike information criterion (AIC) value for a better quality of model fitting.
To examine the robustness of our findings, we further did sensitivity analysis by excluding patients with De Ritis > 2, who may have underlying liver disease.
All statistical analyses were performed using R version 4.4.0 Statistical Software, GraphPad PRISM 8.3.0 (GraphPad Software Inc.) and validated by SPSS Statistics version 29.0 (IBM Corp.). Statistical significance was set at a two-tailed P < 0.05.
Data Availability
All relevant data that support the findings of this study are within the paper or its supplementary material.