| Descriptive and associational approaches |
| Descriptive analysis | Describing microbiological findings and antibiotic use patterns in VAP9 | Simple and intuitive; easy to implement; provides basis for further analyses | Cannot infer causality; susceptible to selection bias; limited generalizability |
| Multivariable association and risk-factor analysis | Examining the associations of the Geriatric Nutritional Risk Index and early prophylactic heparin use with mortality in patients with sepsis10,11 | Enables simultaneous examination of multiple variables; allows adjustment for potential confounders; quantifies associations using effect estimates with confidence intervals | Limited causal inference capacity in exploratory analyses without prespecified exposure and adjustment strategy |
| Nonlinear association modeling | Examining nonlinear associations of biomarkers with mortality in sepsis-associated acute kidney injury and urosepsis using restricted cubic splines12,13 | Preserves continuous variable information; flexibly models nonlinear trends | Sensitive to the number and placement of knots; requires adequate sample size |
| Clinical prediction modeling |
| Diagnostic prediction models | Early identification of bloodstream infection in critically ill patients using LASSO-based predictor selection, logistic regression, and a nomogram14 | Widely used for disease risk estimation and early identification of high-risk patients | Use of AUC alone may overestimate practical usefulness |
| Prognostic prediction models | Predicting short- and longer-term mortality in critically ill patients with coronary artery disease, acute pulmonary embolism, and COPD15-17 | Supports risk stratification and individualized prognostic assessment | Requires external validation before clinical implementation |
| Machine learning-based diagnostic prediction models | Early identification of sepsis-associated acute respiratory distress syndrome using machine learning models based on eICU and MIMIC-IV data18 | Can integrate multidimensional clinical information to generate individualized risk predictions and may support early detection and clinical decision-making | Risk of overfitting; risk of data leakage; requires external validation |
| Machine learning-based prognostic prediction models | Predicting new-onset atrial fibrillation in critically ill patients, critical outcomes in urinary tract infection, and prognosis in urosepsis and catheter-associated urinary tract infection19-22 | May support prognostic risk stratification in complex patient populations | Survival time bias; competing risks; requires time-dependent performance metrics |
| Time-to-event, longitudinal, and dynamic methods |
| Restricted mean survival time analysis | Evaluating survival time with early albumin plus crystalloid therapy in patients with sepsis23 | Does not rely on proportional hazards assumption; results are clinically interpretable | Sensitive to truncation time (τ); may be unstable with insufficient follow-up |
| Longitudinal and joint modeling | Jointly modeling repeated daily SOFA scores and the competing risks of ICU death and discharge in patients with sepsis24 | Captures temporal changes and within- and between-individual variability using repeated measurements; joint models can link longitudinal and event-time processes while accounting for measurement error | Highly sensitive to data completeness; requires careful study design, appropriate measurement time point selection, and rigorous missing data handling |
| Trajectory analysis | Identifying longitudinal trajectories of lactate in sepsis, serum sodium in sepsis with lactic acidosis, and age-adjusted shock index in septic shock25-27 | Captures heterogeneity in longitudinal data | Sensitive to sample size, missing data, and the prespecified number of trajectory classes; requires robust model-selection procedures and sensitivity analyses |
| Causal inference approaches |
| Propensity score methods and inverse probability of treatment weighting | Evaluating the associations of ramelteon exposure with survival in sepsis and albumin infusion with prognosis in ICU patients with cirrhosis and acute kidney injury28,29 | Can improve balance in measured baseline covariates and reduce confounding due to measured characteristics | Sensitive to propensity-score model specification and extreme weights; cannot eliminate unmeasured confounding |
| Causal mediation analysis | Investigating potential mediating roles of inflammatory markers and metabolic or electrolyte-related biomarkers in associations with mortality30,31 | Helps investigate potential mechanistic pathways | Causal interpretation requires strong assumptions regarding confounding, temporal ordering, and model specification; sensitivity analyses are important |
| Target trial emulation | Evaluating early albumin administration in relation to sepsis-associated acute kidney injury and corticosteroid treatment in patients with sepsis32,33 | Aligns observational analyses with a prespecified target-trial framework and may reduce certain design- and time-related biases | Validity depends on data quality, variable availability, and accurate mapping of clinical pathways; prone to unmeasured confounding factors; prone to issues related to complex treatment pathways; robustness and credibility depend on well-specified trial protocols, meticulous operationalization of observational data, and comprehensive sensitivity analyses |
| Artificial intelligence and advanced computational methods |
| Deep learning | Predicting ICU survival using multicohort data and estimating individualized mortality risks under different treatment strategies in patients with atrial fibrillation34,35 | Applicable to outcome prediction and, when integrated with causal inference frameworks, individualized treatment-effect estimation | Requires large amounts of high-quality training data; limited interpretability due to complex, black-box model structures |
| Ensemble learning | Predicting sepsis-associated liver injury using ensemble learning with external multicenter validation36 | Combines multiple base models and may improve predictive stability and generalizability | Increased computational complexity; risk of data leakage |
| Image-based deep learning | Classifying the progression of multiple thoracic abnormalities and localizing newly developed abnormalities on chest radiographs using MIMIC-CXR37 | Can directly extract features from raw images for detection, classification, progression assessment, and lesion localization | Depends on large-scale, manually labeled datasets; labeling cost is high |
| Reinforcement learning | Optimizing sepsis treatment strategies using deep reinforcement learning with expert clinical knowledge38 | Models sequential decision-making under uncertainty and may support personalized and adaptive treatment strategies | Limited prospective clinical evaluation; external validation and safety testing remain important |
| Natural language processing | Using clinical and nursing notes to predict hospital-acquired pressure injury through named-entity recognition39 | Can process large volumes of unstructured clinical text; may support diagnostic and prognostic applications | Performance may vary across tasks, populations, and languages; limited by incomplete EHR data and poor interoperability with existing clinical systems |