Related Experiment Video
Updated: Mar 16, 2026
Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies
Published on: January 16, 2019
Comparing Time-Fixed Mortality Prediction Models and Their Effect on ICU Performance Metrics Using the Simplified
Lars Engerström1, Andrew A Kramer, Thomas Nolin
11Department of Anesthesiology and Intensive Care, Vrinnevisjukhuset, Norrköping, Sweden. 2Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Sweden. 3Department of Cardiothoracic and Vascular Surgery, Linköping University Hospital, Linköping, Sweden. 4Prescient Healthcare Consulting, Charlottesville, VA. 5The Swedish Intensive Care Registry, Karlstad, Sweden. 6Department of Hand Surgery, Plastic Surgery and Burns, Linköping University Hospital, Linköping, Sweden. 7Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden. 8Linköping Academic Research Center, Linköping University, Linköping, Sweden.
Objectives:
To examine ICU performance based on the Simplified Acute Physiology Score 3 using 30-day, 90-day, or 180-day mortality as outcome measures and compare results with 30-day mortality as reference.
Design:
Retrospective cohort study of ICU admissions from 2010 to 2014.
Setting:
Sixty-three Swedish ICUs that submitted data to the Swedish Intensive Care Registry.
Patients:
The development cohort was first admissions to ICU during 2011-2012 (n = 53,546), and the validation cohort was first admissions to ICU during 2013-2014 (n = 57,729).
Interventions:
None.
Measurements And Main Results:
Logistic regression was used to develop predictive models based on a first level recalibration of the original Simplified Acute Physiology Score 3 model but with 30-day, 90-day, or 180-day mortality as measures of outcome. Discrimination and calibration were excellent for the development dataset. Validation in the more recent 2013-2014 database showed good discrimination (C-statistic: 0.85, 0.84, and 0.83 for the 30-, 90-, and 180-d models, respectively), and good calibration (standardized mortality ratio: 0.99, 0.99, and 1.00; Hosmer-Lemeshow goodness of fit H-statistic: 66.4, 63.7, and 81.4 for the 30-, 90-, and 180-d models, respectively). There were modest changes in an ICU's standardized mortality ratio grouping (< 1.00, not significant, > 1.00) when follow-up was extended from 30 to 90 days and 180 days, respectively; about 11-13% of all ICUs.
Conclusions:
The recalibrated Simplified Acute Physiology Score 3 hospital outcome prediction model performed well on long-term outcomes. Evaluation of ICU performance using standardized mortality ratio was only modestly sensitive to the follow-up time. Our results suggest that 30-day mortality may be a good benchmark of ICU performance. However, the duration of follow-up must balance between what is most relevant for patients, most affected by ICU care, least affected by administrative policies and practically feasible for caregivers.
