Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (1,046 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
An acronym for Acute Physiology and Chronic Health Evaluation, a scoring system using routinely collected data and providing an accurate, objective description for a broad range of intensive care unit admissions, measuring severity of illness in critically ill patients.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Acute Physiology and Chronic Health Evaluation; APACHE I; APACHE II; APACHE III.
Where it fits in the MeSH classification
- Broader topics
- Health Status Indicators; Severity of Illness Index
Research landscape
PubMed indexes 7,386 records tagged with the MeSH heading “APACHE” (counts retrieved 2026-10-29). 1,140 of them (15.4%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 2,802 records.
Reviews account for 288 records (3.9%) and meta-analyses for 57. Randomized controlled trials number 536 (7.3%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 860 |
| 2000-2009 | 2,584 |
| 2010-2019 | 2,802 |
| 2020 onward | 1,140 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 288 | 3.9% |
| Meta-analyses | 57 | 0.8% |
| Randomized controlled trials | 536 | 7.3% |
Method: PubMed query "APACHE"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in clinical research
Research methods determine how much a result can be trusted. Randomized trials guard against confounding, systematic reviews and meta-analyses combine many studies, and observational designs are valuable but can show only association. Reporting standards, trial registration and pre-specified outcomes reduce bias. When reading about a method, ask what problem it is designed to solve and which problems it does not solve.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
Risk assessment in sepsis: a new prognostication rule by APACHE II score and serum soluble urokinase plasminogen activator receptor [1]
Abstract reading summary — source excerpts
- Opening excerpt
- IntroductionEarly risk assessment is the mainstay of management of patients with sepsis.
- Closing excerpt
- Prognostication by this rule is confirmed by an independent cohort.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (191 words)
IntroductionEarly risk assessment is the mainstay of management of patients with sepsis. APACHE II is the gold standard prognostic stratification system. A prediction rule that aimed to improve prognostication by APACHE II with the application of serum suPAR (soluble urokinase plasminogen activator receptor) is developed.MethodsA prospective study cohort enrolled 1914 patients with sepsis including 62.2% with sepsis and 37.8% with severe sepsis/septic shock. Serum suPAR was measured in samples drawn after diagnosis by an enzyme-immunoabsorbent assay; in 367 patients sequential measurements were performed. After ROC analysis and multivariate logistic regression analysis a prediction rule for risk was developed. The rule was validated in a double-blind fashion by an independent confirmation cohort of 196 sepsis patients, predominantly severe sepsis/septic shock patients, from Sweden.ResultsSerum suPAR remained stable within survivors and non-survivors for 10 days. Regression analysis showed that APACHE II ≥ 17 and suPAR ≥ 12 ng/ml were independently associated with unfavorable outcome. Four strata of risk were identified: i) APACHE II ConclusionsA novel prediction rule with four levels of risk in sepsis based on APACHE II score and serum suPAR is proposed. Prognostication by this rule is confirmed by an independent cohort.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 22873681 · DOI · PMC3580738
Association of gender with outcomes in critically ill patients [2]
Abstract reading summary — source excerpts
- Opening excerpt
- IntroductionThe influence of gender on mortality and other outcomes of critically ill patients is not clear.
- Closing excerpt
- There was no difference in mortality in acute coronary syndrome, sepsis or trauma.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (280 words)
IntroductionThe influence of gender on mortality and other outcomes of critically ill patients is not clear. Different studies have been performed in various settings and patient populations often yielding conflicting results. We wanted to assess the relationship of gender and intensive care unit (ICU) outcomes in the patients included in the Acute Physiology and Chronic Health Evaluation (APACHE) IV database (Cerner Corporation, USA).MethodsWe performed a retrospective review of the data available in the APACHE IV database. A total of 261,255 consecutive patients admitted to adult ICUs in United States from 1 January 2004 to 31 December 2008 were included. Readmissions were excluded from the analysis. The primary objective of the study was to assess the relationship of gender with ICU mortality. The secondary objective was to evaluate the association of gender with active therapy, mechanical ventilation, length of stay in the ICU, readmission rate and hospital mortality. The gender-related outcomes for disease subgroups including acute coronary syndrome, coronary artery bypass graft (CABG) surgery, sepsis, trauma and chronic obstructive pulmonary disease (COPD) exacerbation were assessed as well.ResultsICU mortality was 7.2% for men and 7.9% for women, odds ratio (OR) for death for women was 1.07 (95% confidence interval (CI): 1.04 to 1.1). There was a statistically significant interaction between gender and age. In patients ConclusionsAmong the critically ill patients, women less than 50 years of age had a lower ICU mortality compared to men, while 50 years of age or older women did not have a significant difference compared to men. Women had a higher mortality compared to men after CABG surgery and lower mortality with COPD exacerbation. There was no difference in mortality in acute coronary syndrome, sepsis or trauma.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 22617003 · DOI · PMC3580638
A comparison between the APACHE II and Charlson Index Score for predicting hospital mortality in critically ill patients [3]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundRisk adjustment and mortality prediction in studies of critical care are usually performed using acuity of illness scores, such as Acute Physiology and Chronic Health Evaluation II (APACHE II), which emphasize physiological derangement.
- Closing excerpt
- However, when acuity of illness scores are unavailable or are not recorded in a standard way, the Charlson index might be considered as an alternative method of risk adjustment and therefore facilitate comparisons between intensive care units.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (269 words)
BackgroundRisk adjustment and mortality prediction in studies of critical care are usually performed using acuity of illness scores, such as Acute Physiology and Chronic Health Evaluation II (APACHE II), which emphasize physiological derangement. Common risk adjustment systems used in administrative datasets, like the Charlson index, are entirely based on the presence of co-morbid illnesses. The purpose of this study was to compare the discriminative ability of the Charlson index to the APACHE II in predicting hospital mortality in adult multisystem ICU patients.MethodsThis was a population-based cohort design. The study sample consisted of adult (>17 years of age) residents of the Calgary Health Region admitted to a multisystem ICU between April 2002 and March 2004. Clinical data were collected prospectively and linked to hospital outcome data. Multiple regression analyses were used to compare the performance of APACHE II and the Charlson index.ResultsThe Charlson index was a poor predictor of mortality (C = 0.626). There was minimal difference between a baseline model containing age, sex and acute physiology score (C = 0.74) and models containing either chronic health points (C = 0.76) or Charlson index variations (C = 0.75, 0.76, 0.77). No important improvement in prediction occurred when the Charlson index was added to the full APACHE II model (C = 0.808 to C = 0.813).ConclusionThe Charlson index does not perform as well as the APACHE II in predicting hospital mortality in ICU patients. However, when acuity of illness scores are unavailable or are not recorded in a standard way, the Charlson index might be considered as an alternative method of risk adjustment and therefore facilitate comparisons between intensive care units.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 19643010 · DOI · PMC2731744
The Norton Scale at Admission Improves APACHE II-Based Mortality Prediction in the Intensive Care Unit: A Retrospective Cohort Study of 5775 Patients [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Background and Objectives: Malnutrition and frailty affect 30-55% of intensive care unit (ICU) patients, yet formal nutritional screening remains inconsistently implemented in routine ICU admission workflows.
- Closing excerpt
- Its widespread availability without additional patient-level data collection positions it as a pragmatic candidate for routine prognostic assessment and for guiding targeted nutritional screening.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (306 words)
Background and Objectives: Malnutrition and frailty affect 30-55% of intensive care unit (ICU) patients, yet formal nutritional screening remains inconsistently implemented in routine ICU admission workflows. The APACHE II score, the standard measure of acute physiological severity, does not capture pre-existing nutritional status or functional reserve. The Norton scale, routinely recorded by nursing staff for pressure-ulcer screening, could serve as a pragmatic proxy for the nutritional-functional axis. We assessed its independent prognostic value at admission for in-hospital and post-ICU mortality. Materials and Methods: Retrospective cohort study of 5775 consecutive adult patients admitted to a Spanish tertiary polyvalent ICU between 2012 and 2019, with APACHE II and Norton scores recorded at admission. The Norton was analysed as continuous and categorised (minimal >14, medium 13-14, high 10-12, very high 5-9). Discrimination was assessed by AUC and DeLong's test, predictive improvement by IDI and NRI, and internal validity by bootstrap resampling (B = 200). Results: Hospital mortality was 12.8% (n = 738), rising from 7.7% in patients with minimal-risk Norton to 34.5% in very high risk. After adjustment for APACHE II, each additional Norton point reduced the odds of death by 7.7% (adjusted OR = 0.923; 95% CI 0.903-0.943). Adding the Norton to APACHE II improved discrimination (AUC 0.865 → 0.872; DeLong p = 0.003; IDI = 0.011; continuous NRI = 0.30). In the highest APACHE II quartile, the absolute mortality difference between minimal and very high Norton categories reached 23.2 percentage points. The Norton's prognostic effect was approximately twice as large for post-ICU mortality (ΔAUC +0.011) as for overall in-hospital mortality (ΔAUC +0.006). Conclusions: The Norton scale at admission improves the prognostic capacity of APACHE II in critically ill patients, particularly for post-ICU mortality. Its widespread availability without additional patient-level data collection positions it as a pragmatic candidate for routine prognostic assessment and for guiding targeted nutritional screening.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42512871 · DOI · PMC13414164
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Systematic review and evaluation of physiological track and trigger warning systems for identifying at-risk patients on the ward [5]
- Research article ICU severity of illness scores: APACHE, SAPS and MPM [6]
- Research article Severity scoring in the critically ill: part 1--interpretation and accuracy of outcome prediction scoring systems [7]
- Research article Prognoses of seriously ill hospitalized patients on the days before death: implications for patient care and public policy [8]
- Research article Prediction of mortality in acute pancreatitis: a systematic review of the published evidence [9]
- Research article Severity of illness and organ failure assessment in adult intensive care units [10]
References
- Giamarellos-Bourboulis EJ, Norrby-Teglund A, Mylona V, Savva A, Tsangaris I, Dimopoulou I, et al.. Risk assessment in sepsis: a new prognostication rule by APACHE II score and serum soluble urokinase plasminogen activator receptor. . 2012. PMID 22873681 · DOI · PMC3580738
- Mahmood K, Eldeirawi K, Wahidi MM. Association of gender with outcomes in critically ill patients. . 2012. PMID 22617003 · DOI · PMC3580638
- Quach S, Hennessy DA, Faris P, Fong A, Quan H, Doig C. A comparison between the APACHE II and Charlson Index Score for predicting hospital mortality in critically ill patients. . 2009. PMID 19643010 · DOI · PMC2731744
- Tejeda-Adell M, de León-Belmar JJ, Pérez-Bermejo M, Pérez-Murillo J, Gomar-Vidal S, Linares-Aguayo S, et al.. The Norton Scale at Admission Improves APACHE II-Based Mortality Prediction in the Intensive Care Unit: A Retrospective Cohort Study of 5775 Patients. . 2026. PMID 42512871 · DOI · PMC13414164
- Gao H, McDonnell A, Harrison DA, Moore T, Adam S, Daly K, et al.. Systematic review and evaluation of physiological track and trigger warning systems for identifying at-risk patients on the ward. Intensive Care Med. 2007. PMID 17318499 · DOI
- Salluh JI, Soares M. ICU severity of illness scores: APACHE, SAPS and MPM. Curr Opin Crit Care. 2014. PMID 25137401 · DOI
- Breslow MJ, Badawi O. Severity scoring in the critically ill: part 1--interpretation and accuracy of outcome prediction scoring systems. Chest. 2012. PMID 22215834 · DOI
- Lynn J, Harrell F, Cohn F, Wagner D, Connors AF. Prognoses of seriously ill hospitalized patients on the days before death: implications for patient care and public policy. New Horiz. 1997. PMID 9017679
- Gravante G, Garcea G, Ong SL, Metcalfe MS, Berry DP, Lloyd DM, et al.. Prediction of mortality in acute pancreatitis: a systematic review of the published evidence. Pancreatology. 2009. PMID 19657215 · DOI
- Afessa B, Gajic O, Keegan MT. Severity of illness and organ failure assessment in adult intensive care units. Crit Care Clin. 2007. PMID 17900487 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-29.
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Evidence strength
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