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Differences in pediatric ICU mortality risk over time
J M Tilford1, P K Roberson, S Lensing
1Department of Pediatrics, University of Arkansas for Medical Sciences, and Arkansas Children's Hospital, Little Rock 72202-3591, USA. TilfordMickJ@exchange.uams.edu
Insights
Pediatric intensive care unit (ICU) mortality risk has significantly decreased over time, with a 15% overall reduction. This improvement impacts the accuracy of the original Pediatric Risk of Mortality (PRISM) score for quality assessment.
Area of Science:
- Pediatric Critical Care Medicine
- Health Services Research
- Biostatistics
Background:
- Pediatric intensive care unit (ICU) mortality risk assessment is crucial for quality evaluation.
- The Pediatric Risk of Mortality (PRISM) score is a widely used tool for predicting mortality in pediatric ICUs.
- Changes in healthcare quality and medical advancements can alter baseline mortality risks over time.
Purpose of the Study:
- To compare pediatric ICU mortality risk between two distinct time periods.
- To evaluate the implications of changing mortality risk on the performance of severity-of-illness systems like PRISM.
- To assess the impact of evolving mortality trends on quality-of-care evaluations in pediatric ICUs.
Main Methods:
- Prospective data collection from 10,833 consecutive admissions across 16 US pediatric ICUs (1993 data).
- Utilized original PRISM coefficients (1980-1985) to calculate mortality probabilities in the contemporary dataset.
- Calculated updated mortality probabilities using logistic regression with original PRISM variables and assessed quality using standardized mortality ratios.
Main Results:
- A significant overall reduction in pediatric ICU mortality risk by 15% (p < .001) was observed.
- Marked improvements in mortality risk were noted for infants (<1 mo: 39% reduction; 1-12 mos: 28% reduction).
- Substantial risk reduction for respiratory diseases (45% improvement) deteriorated the calibration of the original PRISM score, leading to disparities in quality assessment.
Conclusions:
- Observed changes in pediatric ICU mortality risk reflect general improvements in the quality of pediatric intensive care.
- The widespread use of the original PRISM score is now limited due to recent advancements in pediatric ICU care.
- The original PRISM score's utility for quality-of-care assessment has been negated by improved outcomes, necessitating updated or alternative systems.
Objectives:
To compare pediatric intensive care unit (ICU) mortality risk using models from two distinct time periods; and to discuss the implications of changing mortality risk for severity systems and quality-of-care assessment.
Data Sources And Setting:
Consecutive admissions (n = 10,833) from 16 pediatric ICUs across the United States that participate in the Pediatric Critical Care Study Group were recorded prospectively. Data collection occurred during a 12-mo period beginning in January 1993.
Methods:
Data collection for the development and validation of the original Pediatric Risk of Mortality (PRISM) score occurred from 1980 to 1985. The original PRISM coefficients were used to calculate mortality probabilities in the current data set. Updated estimates of mortality probabilities were calculated, using coefficients from a logistic regression analysis using the original PRISM variable set. Quality-of-care tests were performed using standardized mortality ratios.
Results:
Risk of mortality from pediatric ICU admission improved considerably between the two periods. Overall, the reduction in mortality risk averaged 15% (p < .001). Analysis of mortality risk by age indicated a large improvement for younger infants. The mortality risk for infants <1 mo improved by 39% (p < .001). Mortality risk improved by 28% (p < .001) for infants between 1 and 12 mos. Analysis of mortality risk by principal diagnosis indicated substantial improvement in respiratory diseases, including respiratory diseases developing in the perinatal period. The mortality risk for respiratory diseases improved by 45% (p < .001). The improvement in mortality risk substantially deteriorated the calibration of the original PRISM severity system (p < .001). As a result of changing mortality risk, the standardized mortality ratios across the 16 pediatric ICUs demonstrated substantial disparities, depending on the choice of models.
Conclusions:
This study documents differences in pediatric ICU risk of mortality over time that are consistent with a general improvement in the quality of pediatric intensive care. Despite continued widespread use of the original PRISM, recent improvements in pediatric ICU quality of care have negated its usefulness for many intended applications, including quality-of-care assessment.