Mortality following noncardiac surgery assessed by the Saint Louis University Score (SLUScore) for hypotension: a retrospective observational cohort study

Abstract

Background: The Saint Louis University Score (SLUScore) was developed to quantify intraoperative blood pressure trajectories and their associated risk for adverse outcomes. This study examines the prevalence and severity of intraoperative hypotension described by the SLUScore and its relationship with 30-day mortality in surgical subtypes.

Methods: This retrospective analysis of perioperative data included surgical cases performed between January 1, 2010, and December 31, 2020. The SLUScore is calculated from cumulative time-periods for which the mean arterial pressure is below a range of hypotensive thresholds. After calculating the SLUScore for each surgical procedure, we quantified the prevalence and severity of intraoperative hypotension for each surgical procedure and the association between intraoperative hypotension and 30-day mortality. We used binary logistic regression to quantify the potential contribution of intraoperative hypotension to mortality.

Results: We analysed 490 982 cases (57.7% female; mean age 57 yr); 33.2% of cases had a SLUScore>0, a median SLUScore of 13 (inter-quartile range [IQR] 7-21), with 1.19% average mortality. The SLUScore was associated with mortality in 12/14 surgical groups. The increases in the odds ratio for death within 30 days of surgery per SLUScore increment were: all surgery types 3.5% (95% confidence interval [95% CI] 3.2-3.9); abdominal/transplant surgery 6% (95% CI 1.5-10.7); thoracic surgery1.5% (95% CI 1-3.3); vascular surgery 3.01% (95% CI 1.9-4.05); spine/neurosurgery 1.1% (95% CI 0.1-2.1); orthopaedic surgery 1.4% (95% CI 0.7-2.2); gynaecological surgery 6.3% (95% CI 2.5-10.1); genitourinary surgery 4.84% (95% CI 3.5-6.15); gastrointestinal surgery 5.2% (95% CI 3.9-6.4); gastroendoscopy 5.5% (95% CI 4.4-6.7); general surgery 6.3% (95% CI 5.5-7.1); ear, nose, and throat surgery 1.6% (95% CI 0-3.27); and cardiac electrophysiology (including pacemaker procedures) 6.6% (95% CI 1.1-12.4).

Conclusions: The SLUScore was independently, but variably, associated with 30-day mortality after noncardiac surgery.

Keywords: SLUScore (Saint Louis University Score); intraoperative blood pressure; intraoperative hypotension; perioperative outcome; postoperative mortality; surgery-associated mortality risk.

Fig 1

Representation of the statistical analysis performed and the study flow diagram indicating the number of patients excluded based on exclusion criteria and missing data. CCI, Charlson Comorbidity Index; SLUScore, Saint Louis University Score.

Fig 2

(a) Proportion of cases in the SLUScore=0 group and SLUScore >0 group for all surgeries and each surgical group. (b) Mortality rates in the SLUScore=0 and SLUScore >0 groups for all surgeries and each surgical speciality. ENT, ear, nose, and throat; EP, electrophysiology; GI NOR, gastrointestinal non-operating room; SLUScore, Saint Louis University Score; Sx, surgery.

Fig 3

Graphical distribution of the change in the 30-day mortality OR per SLUScore increment and confidence intervals for each surgical speciality. All surgeries: OR 3.5% (95% CI 3.2–3.9), P<0.001; spine and neurosurgery: OR 1.1% (95% CI 0.1–2.1), P<0.029; orthopaedic surgery: OR 1.4 (95% CI 0.7–2.2), P<0.001; thoracic surgery: OR 1.5% (95% CI 1–3.3); thoracic surgery—SLUS30 subgroup: OR 94.1% (95% CI 24.2–203.4) P<0.004 (not represented); ENT surgery: OR 1.62% (95% CI 0–3.3), P<0.050; vascular surgery: OR 3.0% (95% CI 1.9–4.0), P<0.0001; genitourinary surgery: OR 4.8% (95% CI 3.5–6.2), P<0.001; surgery of the GI tract: OR 5.2% (95% CI 3.9–6.4), P<0.001; GI NOR endoscopy: OR 5.5% (95% CI 4.4–6.7), P<0.001; transplant surgery: OR 6% (95% CI 1.5–10.7), P<0.008; general surgery: OR 6.3% (95% CI 5.5–7.1), P<0.001; gynaecologic surgery: OR 6.3% (95% CI 2.5–10.1), P<0.001; pacemaker and EP: OR 6.6% (95% CI 1.1–12.4), P<0.017. CI, confidence interval; ENT, ear, nose, and throat; EP, electrophysiology; GI NOR, gastrointestinal non-operating room; OR, odds ratio; SLUScore, Saint Louis University Score; Sx, surgery.