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Updated: Sep 25, 2025

An R-Based Landscape Validation of a Competing Risk Model
Published on: September 16, 2022
A composite ranking of risk factors for COVID-19 time-to-event data from a Turkish cohort
Ayse Ulgen1, Sirin Cetin2, Meryem Cetin3
1Department of Biostatistics, Faculty of Medicine, Girne American University, Karmi, Cyprus.
Insights
Identifying reliable blood test risk factors for COVID-19 severity is crucial. This study enhances survival analysis using machine learning to pinpoint key indicators for disease progression and recovery.
Area of Science:
- Clinical Medicine
- Biostatistics
- Computational Biology
Background:
- Reliable identification of routine laboratory blood test risk factors for COVID-19 severity and mortality is vital for patient care and hospital management.
- Meta-analysis is commonly used to combine study results for reproducibility, but a more robust approach is needed.
Purpose of the Study:
- To develop a more robust list of risk factors for COVID-19 severity and mortality using routine blood tests.
- To extend standard survival analysis by incorporating machine learning, multivariable analysis, and analyzing both death and recovery events.
Main Methods:
- Extended standard survival analysis on time-to-event data in three directions: machine learning prediction, multivariable analysis, and analyzing time-to-hospital release alongside time-to-death.
- Generated ten ranking lists of risk factors based on these extended analyses.
- Utilized stepwise variable selection in random survival forest to identify optimal prognostic factors.
Main Results:
- Identified 20 out of 30 factors reliably associated with faster death or faster recovery from COVID-19.
- Determined that 10-15 factors can achieve optimal prognosis performance when considering correlations and using stepwise variable selection.
- The final list of significant risk factors includes calcium, white blood cell and neutrophils count, urea and creatine, d-dimer, red cell distribution widths, age, ferritin, glucose, lactate dehydrogenase, lymphocyte, basophils, anemia-related factors, sodium, potassium, eosinophils, and aspartate aminotransferase.
Conclusions:
- The proposed extended survival analysis provides a robust method for identifying COVID-19 risk factors from routine blood tests.
- A refined list of 10-15 key blood test parameters can effectively predict COVID-19 prognosis.
- These findings can aid in clinical decision-making and hospital resource management for COVID-19 patients.
Abstract:
Having a complete and reliable list of risk factors from routine laboratory blood test for COVID-19 disease severity and mortality is important for patient care and hospital management. It is common to use meta-analysis to combine analysis results from different studies to make it more reproducible. In this paper, we propose to run multiple analyses on the same set of data to produce a more robust list of risk factors. With our time-to-event survival data, the standard survival analysis were extended in three directions. The first is to extend from tests and corresponding p-values to machine learning and their prediction performance. The second is to extend from single-variable to multiple-variable analysis. The third is to expand from analyzing time-to-decease data with death as the event of interest to analyzing time-to-hospital-release data to treat early recovery as a meaningful event as well. Our extension of the type of analyses leads to ten ranking lists. We conclude that 20 out of 30 factors are deemed to be reliably associated to faster-death or faster-recovery. Considering correlation among factors and evidenced by stepwise variable selection in random survival forest, 10 ~ 15 factors seem to be able to achieve the optimal prognosis performance. Our final list of risk factors contain calcium, white blood cell and neutrophils count, urea and creatine, d-dimer, red cell distribution widths, age, ferritin, glucose, lactate dehydrogenase, lymphocyte, basophils, anemia related factors (hemoglobin, hematocrit, mean corpuscular hemoglobin concentration), sodium, potassium, eosinophils, and aspartate aminotransferase.
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