Validity of nutritional screening with MUST and SNAQ in hospital outpatients

The majority of hospital outpatients with undernutrition is unrecognized, and therefore untreated. There is a need for an easy and valid screening tool to detect undernutrition in this setting. The aim of this study was to determine the diagnostic accuracy of the MUST (Malnutrition Universal Screening Tool) and SNAQ (Short Nutritional Assessment Questionnaire) tools for undernutrition screening in hospital outpatients.

In a large multicenter-hospital-outpatient population, patients were classified as: severely undernourished (body mass index (BMI) <18.5 (<65 years) or <20 ( ≥ 65 years) and/or unintentional weight loss >5% in the last month or >10% in the last 6 months), moderately undernourished (BMI 18.5-20 (<65 years) or 20-22 ( ≥ 65 years) and/or 5-10% unintentional weight loss in the last 6 months) or not undernourished. Diagnostic accuracy of the screening tools versus the reference method was expressed as sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV).

Out of the 2236 outpatients, 6% were severely and 7% were moderately undernourished according to the reference method. MUST and SNAQ identified 9% and 3% as severely undernourished, respectively. MUST had a low PPV (Se=75, Sp=95, PPV=43, NPV=98), whereas SNAQ had a low Se (Se=43, Sp=99, PPV=78, NPV=96).

The validity of MUST and SNAQ is insufficient for hospital outpatients. While SNAQ identifies too few patients as undernourished, MUST identifies too many patients as undernourished. We advise to measure body weight, height and weight loss, in order to define undernutrition in hospital outpatients.