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Penalized count data regression with application to hospital stay after pediatric cardiac surgery
Zhu Wang1, Shuangge Ma2, Michael Zappitelli3
1Department of Research, Connecticut Children's Medical Center, Hartford, CT, USA zwang@connecticutchildrens.org.
Insights
New statistical methods improve prediction of prolonged hospital stays after pediatric cardiac surgery. Urine biomarkers like NGAL, IL18, and KIM-1 were found to independently predict length of stay (LOS) in children.
Area of Science:
- Biostatistics
- Pediatric Cardiology
- Nephrology
Background:
- Pediatric cardiac surgery is associated with adverse outcomes, including acute kidney injury (AKI) and extended hospital length of stay (LOS).
- Early identification and prediction of these outcomes are crucial for improving patient care.
- Plasma and urine biomarkers show potential for predicting clinical outcomes in this population.
Purpose of the Study:
- To propose and evaluate novel variable selection methods for Poisson and negative binomial (NB) regression models.
- To apply these methods to identify predictors of hospital length of stay (LOS) in children undergoing cardiac surgery.
- To assess the predictive value of specific urine biomarkers for LOS.
Main Methods:
- Development of penalized regression methods, including extended elastic net (Enet), minimax concave (Mnet), and smoothly clipped absolute deviation (Snet) penalties combined with ridge penalties (EMSnet) for Poisson and NB regression.
- A unified algorithm was created for simultaneous parameter estimation and variable selection.
- The proposed methods were evaluated through simulation studies and applied to a multi-center dataset of 311 children undergoing cardiac surgery.
Main Results:
- Simulation studies demonstrated the advantage of the proposed EMSnet methods, particularly with highly correlated predictors.
- Application to the pediatric cardiac surgery data identified early postoperative urine biomarkers, including NGAL, IL18, and KIM-1, as independent predictors of LOS.
- These biomarkers predicted LOS after adjusting for other risk and biomarker variables.
Conclusions:
- The novel penalized regression methods (EMSnet) offer robust variable selection for count data, especially in the presence of multicollinearity.
- Early postoperative urine biomarkers (NGAL, IL18, KIM-1) are significant independent predictors of prolonged hospital length of stay (LOS) in pediatric cardiac surgery patients.
- These findings highlight the potential of non-invasive biomarkers for risk stratification and management in pediatric cardiac surgery.
Abstract:
Pediatric cardiac surgery may lead to poor outcomes such as acute kidney injury (AKI) and prolonged hospital length of stay (LOS). Plasma and urine biomarkers may help with early identification and prediction of these adverse clinical outcomes. In a recent multi-center study, 311 children undergoing cardiac surgery were enrolled to evaluate multiple biomarkers for diagnosis and prognosis of AKI and other clinical outcomes. LOS is often analyzed as count data, thus Poisson regression and negative binomial (NB) regression are common choices for developing predictive models. With many correlated prognostic factors and biomarkers, variable selection is an important step. The present paper proposes new variable selection methods for Poisson and NB regression. We evaluated regularized regression through penalized likelihood function. We first extend the elastic net (Enet) Poisson to two penalized Poisson regression: Mnet, a combination of minimax concave and ridge penalties; and Snet, a combination of smoothly clipped absolute deviation (SCAD) and ridge penalties. Furthermore, we extend the above methods to the penalized NB regression. For the Enet, Mnet, and Snet penalties (EMSnet), we develop a unified algorithm to estimate the parameters and conduct variable selection simultaneously. Simulation studies show that the proposed methods have advantages with highly correlated predictors, against some of the competing methods. Applying the proposed methods to the aforementioned data, it is discovered that early postoperative urine biomarkers including NGAL, IL18, and KIM-1 independently predict LOS, after adjusting for risk and biomarker variables.
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