Covert Assessment of Concurrent and Construct Validity of a Chart to Characterize Fecal Output and Diarrhea in Patients Receiving Enteral Nutrition

Background: An accurate and convenient method for characterizing fecal output and a consistent threshold for classifying diarrhea in patients receiving enteral nutrition are required. The aim of this study is to covertly assess the construct and concurrent validity of a chart for characterizing fecal output and classifying diarrhea in patients receiving enteral nutrition. Methods: The chart was used to monitor fecal output in patients receiving enteral nutrition for a total of 280 patient days. Nurses characterized 291 fecal samples, of which 84 underwent measurement of fecal water using lyophilization and 60 underwent Clostridium difficile enterotoxin analysis using enzyme-linked immunosorbent assay. Construct and concurrent validity was assessed covertly to measure the true performance of the chart in a real-life clinical and research context. Results: Use of the chart demonstrated higher fecal frequency (P ≤ .04), heavier stools (P ≤ .167), more unformed stools (P ≤ .001), higher daily fecal scores (P ...