A retrospective cross-sectional study for predicting 72-h mortality in patients with serum aspartate aminotransferase levels ≥ 3000 U/L

Abstract

Risk factors associated with 72-h mortality in patients with extremely high serum aspartate aminotransferase levels (AST; ≥ 3000 U/L) are unknown. This single-centre, retrospective, case-controlled, cross-sectional study obtained data from medical records of adult patients treated at Saitama Medical Center, Japan, from 2005 to 2019. We conducted a multivariate logistic after adjusting for age, sex, height, weight, body mass index, Brinkman Index, vital signs, biochemical values, updated Charlson Comorbidity Index (CCI) score, CCI components, and underlying causes. A logistic regression model with selected validity risks and higher C-statistic for predicting 72-h mortality was established. During the 15-year period, 428 patients (133 non-survivors and 295 survivors [cases and controls by survival < 72 and ≥ 72 h, respectively]) with AST levels ≥ 3000 U/L were identified. The 72-h mortality rate was 133/428 (31.1%). The model used for predicting 72-h mortality through the assessment of alkaline phosphatase, creatine kinase, serum sodium, potassium, and phosphorus levels had a C-statistic value of 0.852 (sensitivity and specificity, 76.6%). The main independent risk factors associated with 72-h mortality among patients with AST levels ≥ 3000 U/L included higher serum values of alkaline phosphatase, creatine kinase, serum sodium, potassium, and phosphorus.

Figure 1

Flow diagram of patient selection. Among the 1,879,239 patients who underwent testing at our medical centre’s clinical laboratory, 1197 had extremely high outlier values of serum aspartate aminotransferase (AST; ≥ 3000 U/L) during a 15-year period, from 2005 to 2019. After applying the exclusion criteria, 124 patients with cardiopulmonary arrest upon arrival, 6 with unknown outcomes, and 639 metachronous duplicates of the same patient were excluded. Finally, 428 patients, including 133 non-survivors (died within 72 h) and 295 survivors (survived beyond 72 h) were enrolled in this study.

Figure 2

Receiver operating characteristic curve analysis of models that predicted 72-h mortality among patients with extremely high values of serum aspartate aminotransferase. Gray line indicates reference values, comprising age and aspartate aminotransferase (AST); black line indicates prediction mode, comprising alkaline phosphatase (ALP), creatine kinase (CK), sodium, pottasium, and phosphorus values. The predicted probability (p) for the 72-h mortality of the prediction model was calculated using the following formula: p = 1/ [1 + exp (-19.98 + 0.290(ALP^0.2) + 0.348log (CK) + 1.766(Na^0.2) + 1.568(K^0.2) + 0.474(P^0.8))].