ICU Scoring Systems Iman Hassan, MD Pulmonary Medicine Department E-mail: dr.imangalal@gmail.com

Introduction Severity of illness scoring systems are developed to evaluate delivery of care & provide prediction of outcome of groups of critically ill patients who are admitted to ICUs. Scoring systems consists of two parts: a severity score, which is a number (generally the higher this is, the more severe the condition) & a calculated probability of mortality.

Classification of Scoring Systems Anatomical scores: depend on the anatomical area involved. Mainly used for trauma patients [e.g. abbreviated injury score (AIS) & injury severity score (ISS)]. Therapeutic weighted scores: based on the assumption that very ill patients require more complex interventions & procedures than patients who are less ill e.g., the therapeutic intervention scoring system (TISS). Organ-specific score: similar to therapeutic scoring; the sicker a patient the more organ systems will be involved, ranging from organ dysfunction to failure [e.g. sequential organ failure assessment (SOFA)].

Classification of Scoring Systems Physiological assessment: based on the degree of derangement of routinely measured physiological variables [e.g. acute physiology and chronic health evaluation (APACHE) & simplified acute physiology score (SAPS)]. Simple scales: based on clinical judgment (e.g. survive or die). Disease specific: [e.g. Ranson’s criteria for acute pancreatitis, subarachnoid haemorrhage assessment using the World Federation of Neurosurgeons score & liver failure assessment using Child-Pugh or model for endstage liver disease (MELD) scoring].

Types of Scoring Systems First day scoring systems: APACHE scoring systems SAPS (simplified acute physiology score) MPM (mortality prediction model) Repetitive scoring systems: OSF (organ system failure) SOFA (sequential organ failure assessment) ODIN (organ dysfunction & infection system) MODS (multiple organs dysfunction score) LOD (logistic organ dysfunction)

The Ideal Scoring System On the basis of easily/routinely recordable variables Well calibrated A high level of discrimination Applicable to all patient populations Can be used in different countries The ability to predict functional status or quality of life after ICU discharge. No scoring system currently incorporates all these features Calibration: assesses the degree of correspondence between the estimated probability of mortality and that actually observed. Calibration is considered to be good if the predicted mortality is close to the observed mortality Discrimination: means the ability of the scoring model to discriminate between patients who die from those who survive, based on the predicted mortalities especially using a ROC curve, an AUC is required to be > 0.70 Area under ROC: 0.5 –chance performance 1 perfect prediction 0.8 accepted cut-off

Severity scores in Medical & Surgical ICU 1980-85 APACHE SAPS APACHE II 1986-1990 SAPS II MPM 1990-95 APACHE III MODS MPM II ODIN 1996-2000 SOFA CIS 2000-current SAPS III APACHE IV

Acute Physiology & Chronic Health Evaluation (APACHE) Common Scoring Systems Acute Physiology & Chronic Health Evaluation (APACHE)

Acute Physiology & Chronic Health Evaluation (APACHE) The APACHE score is the best-known & most widely used score with good calibration & discrimination. The original APACHE score was developed in 1981 to classify groups of patients according to severity of illness & was divided into 2 sections: physiology score to assess the degree of acute illness & preadmission evaluation to determine the chronic health status of the patient.

Original APACHE score: 34 physiologic measures (0-4) Sum of all acute physiology scores (APS) Worst of the initial 24 hour after ICU admission Chronic health A (excellent health) B C D (severe chronic organ system insufficiency) Crit Care Med 1981; 9:591

Original APACHE score: Crit Care Med 1981; 9:591

APACHE II score: The APACHE II scoring system was released in 1985 and included a reduction in the number of variables to 12. The APACHE II scoring system is measured during the first 24 h of ICU admission with a maximum score of 71. A score of 25 represents a predicted mortality of 50% and a score of over 35 represents a predicted mortality of 80%. APACHE II score is sum of: Acute physiology score Age Chronic health score

APACHE II score: The APACHE II score (0 – 71) Total APACHE II = A+B+C A → APS points B → Age points C → Chronic Health points

APACHE II score: Predicted mortality = - 3.517 + (Score Apache II) * 0.146 Predicted mortality (adjusted) = - 3.517 + (Score Apache II) * 0.146 + diagnostic category weight

High Abnormal Range Low Abnormal Range The APACHE II Score Physiologic Variable High Abnormal Range Low Abnormal Range +4 +3 +2 +1 Rectal Temp (°C) ≥41 39-40.9 38.5-38.9 36-38.4 34-35.9 32-33.9 30-31.9 ≤29.9 Mean Arterial Pressure (mmHg) ≥160 130-159 110-129 70-109 50-69 ≤49 Heart Rate ≥100 140-179 110-139 40-54 ≤39 Respiratory Rate ≥50 35-49 25-34 12-24 10-11 6-9 ≤5 Oxygenatation a)FIO2≥0.5 record A-aDO2 b)FIO2<0.5 record PaO2 ≥500 350-499 200-349 <200 PO2>70 PO2 61-70 PO2 55-60 PO2<55 Arterial pH ≥7.7 7.6-7.69 7.5-7.59 7.33-7.49 7.25-7.32 7.15-7.24 <7.15 HCO3 (mEq/l) ≥52 41-51.9 32-40.9 22-31.9 18-21.9 15-17.9 <15 K (mEq/l) ≥7 6-6.9 5.5-5.9 3.5-5.4 3-3.4 2.5-2.9 <2.5 Na (mEq/l) 160-179 155-159 150-154 130-149 120-129 111-119 ≤110 S. Creat (mqm/dl) ≥3.5 2-3.4 1.5-1.9 0.6-1.4 <0.6 Hematocrit (%) ≥60 50-59.9 46-49.9 30.45.9 20-29.9 <20 TLC (10³/cc) ≥40 20-39.9 15-19.9 3-14.9 1-2.9 <1 GCS MAP = [(2 x diastolic)+systolic] / 3 Age -score <44 → 0 45-54 → 2 55-64 → 3 65-74 → 5 ≥75 → 6 GCS: 15 → 0 14 → 1 13 → 2 12 → 3 11 → 4 10 → 5 9 → 6 8 → 7 7 → 8 6 → 9 5 → 10 4 → 11 3 → 12 JAMA 1993;270(24):2957-2963

The APACHE II Score

The Glasgow Coma Scale (GCS) Lancet 1974;304:81-84

APACHE III score: 17 physiological variables & Total score (0 – 299) APACHE III, released in 1991, was developed with the objectives of improved statistical power, ability to predict individual patient outcome, and identify the factors in ICU that influence outcome variations but it is far more complex than the 2 previous scoring systems. 17 physiological variables & Total score (0 – 299) Acid-base disturbances GCS score – based on the worst Age score 7 co-morbidities (cardiac, respiratory & renal failures excluded) Chest 1991, 100:1619 - 1636

The APACHE III Score

The APACHE III Scoring for Acid-Base disturbances

The APACHE III Scoring for Age Age -score <44 → 0 45-59 → 5 60-64 → 11 65-69 → 13 70-74 → 16 75-85 → 17 ≥85 → 24

The APACHE III Score

The APACHE III Score Shaded areas without score = unlikely or unusual combinations

The APACHE III Scoring for Chronic Health Condition Chronic health condition (Co-morbid condition) AIDS → 23 Hepatic failure → 16 Lymphoma → 13 Metastatic cancer → 11 Leukemia/multiple myeloma → 10 Immunosuppression → 10 Cirrhosis → 4

Prediction at 50%probability APACHE score ROC Prediction at 50%probability Calibration APACHE II 0.85 85.5 APACHE III version (H) 0.90 88.2 48.7 APACHE III version (I) Unpublished 24.2 APACHE III (H) in 2003-04 cohort

APACHE IV score: Limitations: The APACHE IV scoring system was published in 2006. Limitations: Complexity – has 142 variables. But web-based calculations can be done. Developed and validated in ICUs of USA only. Crit Care Med 2006; 34:1297–1310

Simplified Acute Physiology Score (SAPS) Common Scoring Systems Simplified Acute Physiology Score (SAPS)

Simplified Acute Physiology Score (SAPS) The SAPS score was first released in 1984 as an alternative to APACHE scoring. The original SAPS score is obtained in the first 24 h of ICU admission by assessment of 14 physiological variables, but no input of pre-existing disease was included. It has been superseded by the SAPS II & SAPS III, both of which assess the 12 physiological variables in the first 24 h of ICU admission & include weightings for pre-admission health status & age.

Simplified Acute Physiology Score (SAPS) Predicted mortality = -14.4761 + 0,0844 * SAPS II + 6.6158 * log (SAPS II+1) Area under ROC for SAPS is 0.8 where as SAPS II has a better value of 0.86 JAMA 1993;270:2957-2963

SAPS II Score JAMA 1993;270(24):2957-2963 Parameter Value (score) HR <40 (11) 40-69 (2) 70-119 (0) 120-159 (4) >160 (7) SBP <70 (13) 70-99 (5) 100-199 (0) >200 (2) Temp <39°C (0) >39°C (3) PaO2/FIO2 <100 (11) 100-199 (9) >200 (6) UO (ml) <500 (11) >500 (4) >1000 (0) S. Urea <28 (0) 28-83 (6) >84 (10) TLC (10³/cc) <1 (12) 1-20 (0) >20 (3) K <3 (3) 3-4.9 (0) >5 (3) Na <125 (5) 125-144 (0) >145 (1) Bicarb <15 (6) 15-19 (3) >20 (0) Bil <4 (0) 4-5.9 (4) >6 (9) GCS <6 (26) 6-8 (13) 9-10 (7) 11-13 (5) 14-15 (0) Age -score <40 → 0 40-59 → 7 60-69 → 12 70-74 → 15 75-79 → 16 ≥80 → 18 Chronic disease: Metastatic cancer → 9 Hemat.malig → 10 AIDS → 17 Type of admission: Sched. Surgical → 0 Medical → 6 Emer.surgical → 8 JAMA 1993;270(24):2957-2963

SAPS III Scores based on data collected within 1st hour of entry to ICU. Allows predicting outcome before ICU intervention occurs. Better evaluation of individual patient rather than an ICU. Limitations: Time for collecting data Can have greater missing information Intensive Care Med 2005; 31:1345–1355

Sequential Organ Failure Assessment (SOFA) Common Scoring Systems Sequential Organ Failure Assessment (SOFA)

Sequential Organ Failure Assessment (SOFA) Previously known as Sepsis-related Organ Failure Assessment because it was initially developed in 1994 to describe the degree of organ dysfunction associated with sepsis in a mixed, medical-surgical ICU patients. Nowadays, it has since been validated to describe the degree of organ dysfunction in various ICU patient groups with organ dysfunctions not due to sepsis. The SOFA score involves six organ systems (respiratory, cardiovascular, renal, hepatic, central nervous, coagulation), and the function of each is scored from 0 (normal function) to 4 (most abnormal), giving a possible score of 0 to 24.

Sequential Organ Failure Assessment (SOFA) Mortality rate increases as number of organs with dysfunction increases. Unlike other scores, the worst value on each day is recorded. A key difference is in the cardiovascular component; instead of the composite variable, the SOFA score uses a treatment-related variable (dose of vasopressor agents).

Sequential Organ Failure Assessment (SOFA) Maximal (highest total) SOFA score: is the sum of highest scores per individual during the entire ICU stay. A score of >15 predicted mortality of 90%. Mean SOFA score (ΔSOFA): is the average of all total SOFA scores in the entire ICU stay. ΔSOFA for 1st 10 days is significantly higher in non-survivors. Delta SOFA score: maximum SOFA – admission SOFA Crit Care Med 1998;26:1793-1800

SOFA Score μgm/kg/min Crit Care Med 1998;26:1793-1800

Multiple Organ Dysfunction Score (MODS) Common Scoring Systems Multiple Organ Dysfunction Score (MODS)

Multiple Organ Dysfunction Score (MODS) The MODS scores six organ systems: respiratory (PO2/FIO2 in arterial blood); renal (serum creatinine); hepatic (serum bilirubin); cardiovascular (pressure-adjusted heart rate); haematological (platelet count) & CNS (Glasgow Coma Score) with weighted scores (0–4) awarded for increasing abnormality of each organ systems. Scoring is performed on a daily basis. Total score ranges from 0-24. Area under ROC 0.936. ΔMODS predicts mortality to a greater extent than Admission MODS score . Crit Care Med. 1995; 23:1638-52

MODS System 1 2 3 4 Respiratory PO2/FiO2 1 2 3 4 Respiratory PO2/FiO2 >300 226-300 151-225 76-150 <75 Renal Serum Creatinine (μmol/L) <100 101-200 201-350 351-500 >500 Hepatic Serum bilirubin (μmol/L) <20 21-60 61-120 121-240 >240 Cardiovascular (PAR) <10 10.1-15 15.1-20 20.1-30 >30 Hematological Platelet count (100/ μL) >120 120-80 80-50 50-20 Neurological (GCS) 15 14-13 12-10 9-7 <7 Cardiovascular pressure adjusted heart rate (PAR) = ( HR*CVP) /MAP Crit Care Med. 1995; 23:1638-52

MODS Score ICU Mortality Hospital Mortality 0% 1-4 1-2% 7% 5-8 3-5% 0% 1-4 1-2% 7% 5-8 3-5% 16% 9-12 25% 50% 13-16 70% 17-20 75% 82% 21-24 100% Crit Care Med. 1995; 23:1638-52

Logistic Organ Dysfunction System (LODS) Common Scoring Systems Logistic Organ Dysfunction System (LODS)

Logistic Organ Dysfunction System (LODS) Worst values in 1st 24 hrs of ICU stay. Worst value in each of 6 organ systems. Total score ranges from 0-22. Good calibration and discrimination (area under ROC 0.85) JAMA 1996;276:802-810

LODS System Value (Score) Neurological Cardiovascular Hematological GCS 14,15 (0) 13-9 (1) 8-6 (3) 5-3 (5) Cardiovascular HR >140 (1) 140-30 (0) <30 (5) SBP >270 (3) 240-269 (1) 70-89 (1) 69-40 (3) <40(5) Hematological TLC (1000/cc) <1 (3) 1-2.4 (1) 2.4-50 (0) >50 (1) Platelet (10³/cc) <50 (1) >50 (0) Respiratory PO2 <150 (3) >150 (1) Hepatic Bilirubin (mg/dl) <2 (0) >2 (1) PT 0-2.9 s (0) 3 s (1) Renal Urea (mg/dl) >120 (5) 119-60 (3) 59-35 (1) <35 (0) Creatinine (mg/dl) >1.16 (3) 1.59-1.2 (1) <1.2 (0) UO (L/24 hr) >10 (3) 10-0.75 (0) 0.75-0.5 (3) <0.5 (5) JAMA 1996;276:802-810

Clinical Pulmonary Infection Score (CPIS) Common Scoring Systems Clinical Pulmonary Infection Score (CPIS)

Clinical Pulmonary Infection Score (CPIS) A score developed to establish a numerical value of clinical, radiographic, and laboratory markers of pneumonia. Serial measurements of the CPIS could be used to identify survivors versus non-survivors as early as day 3 of therapy. The CPIS correlated with mortality rate. CPIS scores > 6 suggest pneumonia. CPIS is an important variable to monitor during VAP therapy. Patients with VAP having CPIS ≤ 6 can safely discontinue antibiotics after 3 days. AJRCCM 2000;162:501-511

Clinical Pulmonary Infection Score (CPIS) 1 2 Temperature ≥36.5 & ≤38.4 ≥38.5 & ≤38.9 ≥39 & ≤36.4 TLC ≥4 & ≤11 <4 or >12 Tracheal Secretions None Non-purulent Purulent Oxygenation PaO2/FIO2 mmHg >240 or ARDS ≤240 & no ARDS Chest Radiograph No opacity Diffuse (patchy) opacities Localized opacity Progression of Radiograpgic Opacities No progression Progression (after HF & ARDS excluded) Culture of Tracheal Aspirate Pathogenic bacteria cultured in rare/few quantities or no growth Pathogenic bacteria cultured in moderate or heavy quantity AJRCCM 2000;162:501-511

Mortality Probability Model (MPM) Common Scoring Systems Mortality Probability Model (MPM)

Mortality Probability Model (MPM) Not applicable for patients <14yrs, patients with burns, cardiac/ cardiac surgery patients. MPM score: Admission MPM (MPM0) →11 variables MPM at 24 Hrs (MPM24) → 14 variables MPM at 48 Hrs (MPM48) → 11 variables MPM over the time (MPMOT) → (MPM24-MPM0) (MPM48-MPM24) Probability is derived directly from these variables. MPMOT predicted better than MPM0 for long term patients. Crit care med 1988;16:470-477

10 beat/min relative risk MPM0 Variable 1 Level of consciousness Coma / deep stupor No coma/deep stupor Admission Emergency Elective Prior CPR Yes No Cancer Present Absent CRF Infection Probable Not probable Previous ICU admission in 6 mo Surgery before ICU admission SBP HR 10 beat/min relative risk Age 10 years relative risk

Therapeutic Intervention Scoring System (TISS) Common Scoring Systems Therapeutic Intervention Scoring System (TISS)

Therapeutic Intervention Scoring System (TISS) Measuring sickness severity based on type & amount of treatment received. Both clinical & administrative applications: assessing severity of illness Determining resource requirements Assessing use of critical care facilities & function Not standardised Daily data collected from each patient on 76 possible clinical interventions

TISS Four classes of pt recognised: Class I < 10 points does not require ICU Class II 10-19 points 1:2 nurse : pt ratio Class III 20-39 points 1 ICU nurse Class IV > 40 points 1:1 nurse : pt ratio

Other Scores Scores for surgical patients: Thoracoscore (thoracic surgery) Lung Resection Score (thoracic surgery) EUROSCORE (cardiac surgery) ONTARIO (cardiac surgery) Parsonnet score (cardiac surgery) System 97 score (cardiac surgery) QMMI score (coronary surgery) Early mortality risk in redocoronary artery surgery MPM for cancer patients Scores for Pediatric patients: PRISM (Pediatric RISk of Mortality) P-MODS (Pediatric MODS) DORA (Dynamic Objective Risk Assessment) PELOD (Pediatric Logistic Organ Dysfunction) PIM II (Paediatric Index of Mortality II) PIM (Paediatric Index of Mortality) Scores for trauma patients: Trauma Score Revised Trauma Score Trauma and injury Severity score (TRISS) A Severity Characterization of trauma (ASCOT)

Which score to use? APACHE, SAPS, MPM → only of historic significance APACHE II → most widely used in USA SAPS II → commonly used in Europe APACHE III → not in public domain SAPS III, APACHE IV → better design MODS & LODS → uncommonly used

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