Criteria for Severe Acute Malnutrition (SAM)
Children under 5 years of age should be diagnosed with SAM and enrolled in therapeutic feeding programs if they have a weight-for-height Z-score less than -3, clinically evident bilateral pitting edema, or height less than 115 cm with weight-for-height less than 70% of median. 1, 2
Primary Diagnostic Criteria
The diagnosis of SAM in children under 5 years relies on three key anthropometric and clinical measures:
Anthropometric Measures
- Weight-for-height Z-score < -3 (or < 70% of median WHO growth standards) is the primary anthropometric criterion 1, 3, 4, 5
- Mid-upper arm circumference (MUAC) < 115 mm for children ≥6 months of age serves as an alternative screening tool 5, 6
- Children with height < 115 cm should be evaluated using weight-for-height criteria 1
Clinical Criterion
- Bilateral pitting edema (clinically evident nutritional edema) is diagnostic of SAM regardless of weight measurements 1, 2, 3, 5
Age-Specific Considerations
Infants Less Than 6 Months
- Use the same weight-for-height Z-score < -3 threshold 2
- Bilateral pitting edema remains a diagnostic criterion 2
- Weight-for-height remains the standard anthropometric measure for this age group 2
Children 6-59 Months
- All three criteria (weight-for-height Z-score, MUAC, and edema) apply 3, 4, 5
- MUAC and edema alone capture 86% of children meeting SAM criteria and 89% of those at highest mortality risk 6
Additional Enrollment Considerations
Medical referral by healthcare personnel constitutes a third pathway for enrollment in therapeutic feeding programs, even if strict anthropometric criteria are not met 1
Common Pitfalls
- Neglecting edema assessment: Bilateral pitting edema is often overlooked but is independently diagnostic of SAM 7
- Inadequate anthropometric documentation: Studies show weight-for-height Z-scores are not calculated in up to 61% of cases in some settings 7
- Using outdated growth standards: WHO growth standards should be used rather than older NCHS guidelines, as WHO criteria identify 56.7% more high-risk children 6
- Missing MUAC measurements: MUAC is a rapid screening tool that should not be neglected, particularly in resource-limited settings where it can identify the majority of NRU-eligible children 6
Clinical Context
Children meeting SAM criteria have a 9 times higher mortality risk than well-nourished children 5, and those identified by WHO criteria but missed by older screening methods have 10 times greater mortality than children without SAM 6. The case fatality rate ranges from 5.9% to 16% in hospitalized children with SAM 4, 7, emphasizing the critical importance of accurate identification and prompt enrollment in therapeutic feeding programs.