Start learning
Features
Note-taking features
Keep your study notes at hand, and organize them into as many folders as you want
Medical Calculators
Acces a growing colection of medical calculators made to help any resident in his practice
Custom lessons
You can edit any lesson or create a new one to include your own content.
All your edits are private.
Practice tabSOON
Test yourself by answering multiple or single style choice questions or solving cascading clinical cases
Social featuresSOON
Connect with your coleagues, chat about the last case, or share custom lessons made by you and your class members.
Medical subjects
75
Anatomy
3
Obstetrics & Gynaecology
1
Orthopedics & Traumatology
Medical Tools
43
Medical calculators
Tools Medical calculators Intensive care

Mastering APACHE II: A Practical Guide to Scoring and Calculating Severity of Illness

The APACHE-2 Score

The APACHE II (Acute Physiology and Chronic Health Evaluation II) score is a severity-of-illness scoring system used in critical care medicine. It is designed to assess the severity of disease and predict the risk of mortality for patients admitted to an intensive care unit (ICU). The score is calculated based on various physiological measurements and patient information collected within the first 24 hours of ICU admission.

The APACHE II score takes into account a patient's age, acute physiological derangements, and pre-existing health conditions. It consists of 12 physiological variables, including:

  1. Temperature
  2. Mean arterial pressure
  3. Heart rate
  4. Respiratory rate
  5. Oxygenation
  6. Arterial pH
  7. Serum sodium
  8. Serum potassium
  9. Serum bicarbonate
  10. Serum creatinine
  11. Hematocrit
  12. White blood cell count
  13. Glasgow Coma Scale score
  14. Presence or absence of chronic health conditions

Each physiological variable is assigned a score based on its deviation from the normal range, and these scores are summed to calculate the total APACHE II score. The score ranges from 0 to 71, with higher scores indicating a greater severity of illness and higher risk of mortality. The APACHE II score provides a standardized and objective method to assess the severity of disease and predict patient outcomes in the ICU.

The APACHE II score is widely used in clinical research and critical care settings for several purposes:

  • Severity assessment: It helps healthcare professionals evaluate the severity of illness and quantify the physiological derangements in critically ill patients. This information aids in determining the appropriate level of care and treatment interventions.
  • Prognostic tool: The APACHE II score is used to predict the risk of mortality for ICU patients. Higher scores are associated with an increased likelihood of death, while lower scores indicate a better prognosis. This information can assist clinicians in discussing treatment options, making decisions regarding life support, and informing patients and their families about expected outcomes.
  • Research and benchmarking: The APACHE II score is used in clinical research to evaluate the effectiveness of new treatments, compare outcomes across different patient populations or hospitals, and assess the impact of interventions on patient survival rates. It serves as a standardized tool for data analysis and comparison.
  • Quality improvement: Hospitals and healthcare systems may use the APACHE II score to monitor and improve the quality of care provided in their ICUs. By tracking patient outcomes and comparing them to predicted mortality rates based on the APACHE II score, healthcare providers can identify areas for improvement and implement strategies to enhance patient care.

It's worth noting that while the APACHE II score is a valuable tool in critical care medicine, it should not be used in isolation to guide clinical decision-making. It is best utilized in conjunction with other clinical assessments, medical expertise, and patient-specific factors to provide a comprehensive evaluation of a patient's condition.

Last update: 29 Jun 2023 21:04
Statistical data taken from the following studiy: [1]

Please note that the calculator provides a rough estimate of mortality and it's important to consider that for low scores, mortality could be higher without treatment, while for patients with high scores, proper management could potentially save a patient's life.

Please note that 1 mEq/L doesn't always equal 1 mmol/L:

  • For K+ (potassium), Na+ (Sodium/Natrium) and HCO3- (Bicarbonate ions) this is true,
  • For Ca2+ (Calcium) or Mg2+ (magnesium), 2 mEq/L is equal to 1 mmol/L,
  • For PO43- (phosphate ions), 3 mEq/L are equal to 1 mmol/L.
Outcome Based on Score Groups

In one study (on 552 patients) trying to assess the performance of the APACHE II score, patients were assigned into 4 groups depending on the score's value: [5]

  • Group 1: patients with values between 31-40
  • Group 2: patients with values between 21-30
  • Group 3: patients with values between 11-20
  • Group 4: patients with values between 0-10

Results

  • All patients in groups 1 & 2 died (228 patients)
  • Group 3: 71.54% survived; 28.54% died (in total 123 patients)
  • Group 4: 201 patients, which all survived

Based on these results, the authors successfully demonstrated that a strong correlation exists between the APACHE II score and patient outcome.

How should residents use such a score ?
  • Start by using the APACHE II score (under supervision).
  • This is not a hard rule, but patients with a score of ≥16-17 should be prioritized as they have a higher mortality risk.
  • Depending on the situation, dynamically adjust the score. Use a lower cutoff value (12-13 or even lower) for more general or easier procedures, and use a higher cutoff value for more invasive or difficult ones (16-18).
  • Learn which patient groups the score may better distinguish. For example, an elderly patient with a higher score may be at a greater risk compared to a younger patient with the same score. Conversely, the inverse may be true for lower scores. These scores are like medical life hacks if used effectively.
  • Start incorporating more challenging/newer scores. Read statistical studies, pay attention to details, and validate all the data. Always seek guidance from your supervisor.
APACHE II vs. APACHE IV Scores

Key Points from the studies
comparing the two scores

In a prospective study involving 128 patients, the APACHE II Score exhibited a slightly higher Area Under the Curve (0.78) compared to the newer score (0.74). [3]

Key Statistics:

  • When comparing survivors and non-survivors:
  • The mean APACHE II Score for survivors was 14.10 (± 5.09), while for non-survivors it was 19.21 (± 4.84).
  • The mean APACHE IV Score for survivors was 56.6 (± 20.29), and for non-survivors it was 77.9 (± 26.83).
  • The range of APACHE II scores for all patients was 3 to 32, whereas for the newer score, the range was wider, ranging from 13 to 156.

Practical Application

After analyzing the data, the authors identified cutoff values for each score that effectively differentiated survivors from non-survivors: 16 for APACHE II and 65 for APACHE IV. However, the authors noted that although the sensitivity and specificity of both scores were similar (as indicated by the AUC), they were not flawless. Therefore, they recommend combining these scores with other laboratory values, clinical data, and imaging results to enhance diagnostic accuracy. [3]

Among patients with an APACHE II score < 17, 23% were non-survivors, whereas among patients with an APACHE IV score < 65, 29% were non-survivors. The APACHE II score performed slightly better at the lower end (more sensitive) and exhibited higher specificity (fewer survivors with an APACHE II score ≥16 compared to an APACHE IV score ≥65). [3]

Additionally, another study conducted in 2018, involving 1670 patients, demonstrated similar results on Indian patients. The study revealed that the APACHE II Score remained effective in predicting outcomes, although the APACHE IV score showed slightly better calibration for this specific population group. This finding further supports the continued relevance and utility of the APACHE II score in different patient populations, including Indian patients. [4]

Disclaimer:

Although the sample size for such complex and widely used scores was small, it can be concluded that the APACHE II score remains relevant and competitive with newer scores. It is also easier to use and requires less laboratory work. However, residents should still learn to use and interpret the newer scores.

References
1. Table: Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II Scoring System* - MSD Manual Professional Edition; https://www.msdmanuals.com/professional/multimedia/table/acute-physiologic-assessment-and-chronic-health-evaluation-apache-ii-scoring-system; Accessed: 2023-06-30
2. APACHE scoring as an indicator of mortality rate in ICU patients: a cohort study; Hassan Mumtaz, Muhammad K. Ejaz et al.; Annals of Medicine and Surgery, 85, 3, 3 2023
3. Comparison of APACHE II and APACHE IV score as predictors of mortality in patients with septic shock in intensive care unit; Summit D. Bloria, Rajeev Chauhan et al.; Journal of Anaesthesiology Clinical Pharmacology, Publish Ahead of Print, 10 2022
4. Mortality Prediction Using Acute Physiology and Chronic Health Evaluation II and Acute Physiology and Chronic Health Evaluation IV Scoring Systems: Is There a Difference?; Ramesh Venkataraman, Vijayaprasad Gopichandran et al.; Indian Journal of Critical Care Medicine : Peer-reviewed, Official Publication of Indian Society…
5. APACHE scoring as an indicator of mortality rate in ICU patients: a cohort study; Hassan Mumtaz, Muhammad K. Ejaz et al.; Annals of Medicine and Surgery, 85, 3, 3 2023
Custom citation style optimized for readability:
Title -> Authors -> Source -> Date
Reset
Lesson authors: Dr. Mironescu Olivier, Dr. Huțuleac Oana-Mihaela
Published on: 29 Jun 2023 21:04
Open in mediakronos:
success42

The APACHE II (Acute Physiology and Chronic Health Evaluation II) score is a severity-of-illness scoring system used in critical care medicine. It is designed to assess the severity of disease and predict the risk of mortality for patients admitted to an intensive care unit (ICU). The score is calculated based on various physiological measurements and patient information collected within the first 24 hours of ICU admission.

The APACHE II score takes into account a patient's age, acute physiological derangements, and pre-existing health conditions. It consists of 12 physiological variables, including:

  1. Temperature
  2. Mean arterial pressure
  3. Heart rate
  4. Respiratory rate
  5. Oxygenation
  6. Arterial pH
  7. Serum sodium
  8. Serum potassium
  9. Serum bicarbonate
  10. Serum creatinine
  11. Hematocrit
  12. White blood cell count
  13. Glasgow Coma Scale score
  14. Presence or absence of chronic health conditions

Each physiological variable is assigned a score based on its deviation from the normal range, and these scores are summed to calculate the total APACHE II score. The score ranges from 0 to 71, with higher scores indicating a greater severity of illness and higher risk of mortality. The APACHE II score provides a standardized and objective method to assess the severity of disease and predict patient outcomes in the ICU.

The APACHE II score is widely used in clinical research and critical care settings for several purposes:

  • Severity assessment: It helps healthcare professionals evaluate the severity of illness and quantify the physiological derangements in critically ill patients. This information aids in determining the appropriate level of care and treatment interventions.
  • Prognostic tool: The APACHE II score is used to predict the risk of mortality for ICU patients. Higher scores are associated with an increased likelihood of death, while lower scores indicate a better prognosis. This information can assist clinicians in discussing treatment options, making decisions regarding life support, and informing patients and their families about expected outcomes.
  • Research and benchmarking: The APACHE II score is used in clinical research to evaluate the effectiveness of new treatments, compare outcomes across different patient populations or hospitals, and assess the impact of interventions on patient survival rates. It serves as a standardized tool for data analysis and comparison.
  • Quality improvement: Hospitals and healthcare systems may use the APACHE II score to monitor and improve the quality of care provided in their ICUs. By tracking patient outcomes and comparing them to predicted mortality rates based on the APACHE II score, healthcare providers can identify areas for improvement and implement strategies to enhance patient care.

It's worth noting that while the APACHE II score is a valuable tool in critical care medicine, it should not be used in isolation to guide clinical decision-making. It is best utilized in conjunction with other clinical assessments, medical expertise, and patient-specific factors to provide a comprehensive evaluation of a patient's condition.

APACHE II score calculator, severity of illness calculator, mortality risk calculator, ICU scoring calculator, critical care scoring tool, APACHE II lesson, severity of illness assessment, risk prediction, critical care education, ICU scoring system, physiological variables, patient outcomes, mortality prediction, clinical decision-making, research tool, quality improvement, prognostic discussions, patient communication, healthcare professionals, intensive care units, critical care settingsMastering APACHE II: A Practical Guide to Scoring and Calculating Severity of IllnessThe APACHE-2 Score0000
Feed
Learn
Practice
Social
My account