Utility of skin testing in nutritional assessment: a critical review

To evaluate the claim that delayed cutaneous hypersensitivity skin testing is useful in nutritional assessment of hospitalized patients, we reviewed the English language literature of the last 12 years. Although several hundred publications discussed delayed cutaneous hypersensitivity testing and nutritional status, only 15 provided new, objective data correlating these variables in hospitalized adults. Of these, only three provided age-matched control groups to control for antigen variability, lack of prior exposure, and other technical problems. The majority of reports took no account of diseases (cancer, immune disease, infection) or therapies (radiation, drugs, surgery) known to affect skin test response. In the reports specifying different degrees of malnutrition, the most important group, those with less than obvious malnutrition, were not abnormal by skin testing. Ten reports described serial skin testing during nutritional intervention. Non reported serially tested controls without nutritional intervention, important since serial testing alone can augment skin test response. Nonnutritional intercurrent therapy which might affect skin tests was seldom mentioned. In the few reports specifying that nutritional repletion was even achieved, repleted patients were not separated from unrepleted in subsequent analyses. No report examined skin testing for its predictive accuracy, cost/benefit ratio, or influence on outcome. Because of these problems in experimental design, the frequent lack of appropriate controls, and the low specificity of abnormal delayed cutaneous hypersensitivity responses, we conclude that the utility of skin testing in nutritional assessment remains unproved.