Ethics is a moral code of what we believe to be universally accepted principles of rightness and wrongness that influences our medical decisions. Ever-advancing technology and therapies constantly challenge and call into question previously established ethical norms. The most accessible approach is committing to the following principles: respect for autonomy, beneficence, nonmaleficence, and justice.¹ These principles are dependent on a thorough understanding of the patient’s illness and how medical interventions, or the lack of will, impact his quality of life. What to advise may not be so easy and often the progress of the clinical course and morbidity and predictive scores are used to give the physician, patient, and family the global perspective into his illness.

These scores help benchmark the quality of care and aide with triage of patients who would benefit from care in the intensive care unit. They are also helpful with prognostication and guide the physician’s goals of care discussion with the patient or family members, particularly when the clinical course is equivocal.

APACHE

In 1985, The Acute Physiology and Chronic Health Evaluation (APACHE) II is a scoring classification of disease severity using acute physiologic score (APS) based on 12 physiologic measurements, age, and chronic health points.^2,3 APACHE II score of less than 25 points has less than or equal to 50% mortality with more than or equal to 35 points had 80% mortality.³ Criticism to APACHE II is that it provided information regarding severity of illness of patient groups but not individual patients.^2,4 In 1991, the APACHE III revision provided risk stratification of individual patients within defined patient groups and the APACHE III Score and reference data on disease categories and treatment location allowed risk estimate for hospital mortality.⁵ There was a greater emphasis on the impact of the APS and the APACHE III Score range from 0-299. Along with Simplified Acute Physiology Score (SAPS) II and Mortality Probability Model (MPM) II, APACHE III was believed to have significantly different predicted mortality from observed.^6-8 In 2006, APACHE IV (Score 0-252) remodeled the physiologic variables and weights and included 4 new predictor variables: (1) presence of mechanical ventilation; (2) use to thrombolytic therapy for acute myocardial infarction; (3) adjustments for prognostic implications of Glasgow Coma Scale (GCS) and Pao₂ and Fio₂; and (4) inability to assess GCS due to sedation or paralysis.⁸ APACHE IV has excellent discrimination with an area under a receive operating characteristic curve (AU-ROC) of 0.88. AU-ROC more than 0.80 indications good discrimination.⁸ Observed and mean predicted mortality were 13.5% and 13.55% (p = 0.76)⁸ (Table 36-1).

SAPS

Another scoring system to predict mortality is the Simplified Acute Physiology Score (SAPS) II created in 1993.⁹ It used physiologic variables, age, type of admission, and three disease variables (acquired immunodeficiency syndrome, metastatic disease, and hematologic malignancy) and found to have Goodness of fit test P = 0.883 and P = .103 in developmental and validated samples.⁹ The ROC is 0.88 developmental and 0.86 in validated sample.⁹

It has been hypothesized that SAPS II needs to be updated because: (1) there is a major change in prevalence of disease and therapeutic interventions; (2) SAPS II is based on data from Europe and North America only; (3) the development of computers; and (4) need for country-representative database.^10,11 In 2005, SAPS III was developed to assess disease severity and predict status on hospital discharge based on data upon ICU admission.^10,11 SAPS III admission score is based on three “boxes.” Box I involves patient characteristics such as age, previous health status, comorbidities, location before ICU admission, length of stay in hospital before ICU, and use of major therapeutic options such as vasoactive drugs before ICU admission.^10,11 Box II involves circumstances of ICU admission like reason for admission, anatomic site of surgery, planned or unplanned ICU admission, surgical status and infection.^10,11 Box III is degree of physiologic derangement at ICU admission or within 1 hour before or after admission.^10,11 The physiologic variables include lowest GCS, highest heart rate, lowest systolic blood pressure, highest bilirubin, highest temperature, highest creatinine, highest leukocytes, lowest platelets, lowest pH, and ventilator support and oxygenation.^10,11 ROC was 0.848 and the Hosmer-Lemeshow goodness-of-fit test H of 10.56 (p = 0.39) and Hosmer-Lemeshow goodness of fits test C of 14.29 (p = 0.16)^10,11 (Table 36-2).

MPM₀

Mortality Probability Model (MPM₀) II, another severity scoring system that predicts mortality from 15 variables within 1 hour of ICU admission was thought to overpredict mortality.^12,13 The updated Mortality Probability Model (MPM₀) III had new variables: “zero factor” for low risk mortality risk in elective surgery patients with no other mortality risk, “full code” variable, and 7 age related interaction terms.¹³ MPM₀ III was found to have area under the ROC 0.826 (95% confidence interval 0.822-0.831) and Hosmer-Lemeshow statistic of 11.52 (p = 0.1740).¹³

SOFA

A prospective multicenter study where the median length of ICU stay was 5 days and the ICU mortality was 22% multiple organ dysfunction and high Sequential Organ Failure Assessment (SOFA) score were associated with increased mortality.^14-16 A subgroup of patients who had an ICU stay of more than or equal to 1 week had higher respiratory, cardiovascular, and neurologic scores. SOFA score increased to 44% in nonsurvivors but only 20% in survivors (P < 0.001) and decreased by 33% in survivors compared to 21% in nonsurvivors (P < 0.001).¹⁶ With a SOFA score >15, mortality was 90% (Sensitivity 31%, Specificity 99%, correct classification 84%).¹⁶ Primarily used in sepsis, modified versions of SOFA have been used in critical care triage of patients in mass disasters and cardiac patients.^17,18 In the modified version for critical care triage of patients from mass disasters, platelet count is removed, arterial oxygen saturation replaces partial pressure of arterial oxygen, and clinical assessment of jaundice replaces serum bilirubin. Area under the receiver operating characteristic curve (ROC) decreased from day 1 (ROC = 0.83) to Day 5 (ROC = 0.74).¹⁷ Another study on post cardiac surgical patients showed good correlation with mortality with ROC 0.841 on admission to area under ROC 0.82 on postoperative day 4, and area under ROC 0.77 on postoperative day 7.¹⁸ A recent retrospective cohort suggested that SOFA’s score prediction of mortality from sepsis diminishes after fifth ICU day¹⁹ (Table 36-3).

MODS

In 1995, Marshall et al created the multiple organ dysfunction score (MODS).²⁰ The score correlated to ICU mortality when applied during first ICU day and over course of ICU stay. At 9-12 points, mortality was 25%; at 13-16 points, mortality was 50%; at 17-20 points, mortality was 75%; and more than 20 points mortality was 100%. ROC was 0.928-0.936.²⁰ (See Table 36-4).