The Mortality Risk Index can help the clinician decide if nutritional support should be initiated, continued or stopped in the critically ill patient. It combines information on the patient's nutritional status, underlying disease and the treatability of that disease.
Mortality Risk Factor
mortality risk index =
= (nutritional risk factor) * (clinical risk factor)
Deriving the Nutritional Risk Factor
nutritional risk factor for a patient with marasmus =
= 141.9 - (18.5 * (serum albumin)) - (0.14 * (serum transferrin)) - (0.77 * (triceps skinfold thickness)) - (8.73 * (CMI score))
nutritional risk factor for a patient with kwashiorkor =
= 157.6 - (24 * (serum albumin)) - (0.18 * (serum transferrin)) + (0.03 * (triceps skinfold thickness)) - (18.4 * (CMI score))
nutritional risk factor for a patient with mixed kwashiorkor-marasmus =
= 114.7 - (4 * (serum albumin)) - (0.17 * (serum transferrin)) - (1.5 * (triceps skinfold thickness)) - (16.6 * (CMI score))
where:
• Somatic measurements include arm muscle circumference, creatinine-height index, triceps skinfold thickness and body weight.
• Marasmus involves protein-calorie malnutrition, with reduction in body weight and other somatic measurements but relatively normal serum proteins (albumin, transferrin) and total lymphocyte count.
• Kwashiorkor indicates protein malnutrition with normal somatic measurements but reductions in serum proteins and total lymphocyte count.
• Mixed kwashiorkor-marasmus indicates an admixture of both marasmus and kwashiorkor, with reduced somatic measurements and serum proteins.
• Serum albumin is in g/dL.
• Serum transferrin is in mg/dL.
• Triceps skinfold thickness is in mm.
• CMI indicates cell-mediated immune reaction to intradermal injection of antigen; an area of induration > 10 mm is scored 2, an area of induration 5-10 mm is scored 1, and a score <5 mm is scored 0.
Deriving the Clinical Risk Factor
clinical risk factor =
= (diagnosis factor) / (treatability factor)
where:
• Diagnosis factor is the stage of disease severity; 1 if the most serious condition is not life-threatening and is limited, 2 if the most serious condition is not life-threatening but is extensive, 3 if the most serious condition is life-threatening but not yet widespread, 4 if the most serious condition is life-threatening and widespread
•The treatability factor is 4 if the most serious condition is eminently treatable with no expected complications; 3 if the most serious condition is eminently treatable but with expected complications; 2 if the most serious condition is difficult to treat but palliation is expected; 1 if the most serious condition is virtually nontreatable and can only hope for palliation
Interpretation
The Mortality Risk Index should be calculated at least weekly. Trauma patients often will show significant changes in the index over relatively short periods of time.
A Mortality Risk Index > 150 usually indicates that the patient will die.
A Mortality Risk Index > 150 for 2 consecutive weeks indicates that continued nutritional support will not change the eventual clinical outcome for the patient.
• Exception: trauma patients.
Specialty: Nutrition
ICD-10: ,
