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Multicenter International Cohort Validation of a Modified Sequential Organ Failure Assessment Score Using the
Shayan Rakhit1,2,3, Li Wang1,4, Christopher J Lindsell4
1Critical Illness, Brain Dysfunction, and Survivorship (CIBS) Center, Nashville, TN.
Objective:
In a multicenter, international cohort, we aimed to validate a modified Sequential Organ Failure Assessment (mSOFA) using the Richmond Agitation-Sedation Scale, hypothesized as comparable to the Glasgow Coma Scale (GCS)-based Sequential Organ Failure Assessment (SOFA).
Summary Background Data:
The SOFA score, whose neurologic component is based on the GCS, can predict intensive care unit (ICU) mortality. But, GCS is often missing in lieu of other assessments, such as the also reliable and validated Richmond Agitation Sedation Scale (RASS). Single-center data suggested an RASS-based SOFA (mSOFA) predicted ICU mortality.
Methods:
Our nested cohort within the prospective 2016 Fourth International Study of Mechanical Ventilation contains 4120 ventilated patients with daily RASS and GCS assessments (20,023 patient-days, 32 countries). We estimated GCS from RASS via a proportional odds model without adjustment. ICU mortality logistic regression models and c-statistics were constructed using SOFA (measured GCS) and mSOFA (measured RASS-estimated GCS), adjusted for age, sex, body-mass index, region (Europe, USA-Canada, Latin America, Africa, Asia, Australia-New Zealand), and postoperative status (medical/surgical).
Results:
Cohort-wide, the mean SOFA=9.4+/-2.8 and mean mSOFA = 10.0+/-2.3, with ICU mortality = 31%. Mean SOFA and mSOFA similarly predicted ICU mortality (SOFA: AUC = 0.784, 95% CI = 0.769-0.799; mSOFA: AUC = 0.778, 95% CI = 0.763-0.793, P = 0.139). Across models, other predictors of mortality included higher age, female sex, medical patient, and African region (all P < 0.001).
Conclusions:
We present the first SOFA modification with RASS in a "real-world" international cohort. Estimating GCS from RASS preserves predictive validity of SOFA to predict ICU mortality. Alternative neurologic measurements like RASS can be viably integrated into severity of illness scoring systems like SOFA.
Insights
A modified Sequential Organ Failure Assessment (mSOFA) using the Richmond Agitation-Sedation Scale (RASS) effectively predicts intensive care unit (ICU) mortality, comparable to the traditional Glasgow Coma Scale (GCS)-based SOFA. This validates RASS as a viable alternative for neurologic assessment in critical care scoring systems.
Area of Science:
- Critical Care Medicine
- Clinical Epidemiology
- Health Outcomes Research
Background:
- The Sequential Organ Failure Assessment (SOFA) score, utilizing the Glasgow Coma Scale (GCS) for its neurologic component, is a key predictor of intensive care unit (ICU) mortality.
- GCS is frequently unavailable, with the Richmond Agitation-Sedation Scale (RASS) often used as a reliable alternative.
- Previous single-center studies suggested that an RASS-based SOFA (mSOFA) could predict ICU mortality.
Purpose of the Study:
- To validate a modified SOFA (mSOFA) score using RASS in a large, international cohort.
- To assess if mSOFA, derived from RASS, demonstrates comparable predictive accuracy for ICU mortality to the traditional GCS-based SOFA.
Main Methods:
- A nested cohort of 4120 mechanically ventilated patients from the 2016 Fourth International Study of Mechanical Ventilation was analyzed.
- GCS was estimated from RASS using a proportional odds model. Both SOFA (using measured GCS) and mSOFA (using RASS-estimated GCS) were constructed.
- Logistic regression models and c-statistics were used to compare the predictive performance of SOFA and mSOFA for ICU mortality, adjusted for covariates.
Main Results:
- The study included 4120 patients across 32 countries, with a mean ICU mortality of 31%.
- Both SOFA (AUC = 0.784) and mSOFA (AUC = 0.778) demonstrated similar and strong predictive capabilities for ICU mortality (P = 0.139).
- Higher age, female sex, medical patient status, and African region were independently associated with increased mortality.
Conclusions:
- This study presents the first international validation of an RASS-based SOFA modification (mSOFA) in a real-world setting.
- Estimating GCS from RASS maintains the predictive validity of the SOFA score for ICU mortality.
- Alternative neurologic assessments like RASS can be effectively integrated into critical care severity scoring systems.
