Derivation and External Validation of a Clinical Prediction Model for Viral Diarrhea Etiology in Bangladesh

BACKGROUND: Antibiotics are commonly overused for diarrheal illness in many low- and middle-income countries, partly due to a lack of diagnostics to identify viral cases, in which antibiotics are not beneficial. This study aimed to develop clinical prediction models to predict risk of viral-only diarrhea across all ages, using routinely collected demographic and clinical variables. METHODS: We used a derivation dataset from 10 hospitals across Bangladesh and a separate validation dataset from the icddr,b Dhaka Hospital. The primary outcome was viral-only etiology determined by stool quantitative polymerase chain reaction. Multivariable logistic regression models were fit and externally validated; discrimination was quantified using area under the receiver operating characteristic curve (AUC) and calibration assessed using calibration plots. RESULTS: Viral-only diarrhea was common in all age groups (<1 year, 41.4%; 18–55 years, 17.7%). A forward stepwise model had AUC of 0.82 (95% confidence interval [CI], .80–.84) while a simplified model with age, abdominal pain, and bloody stool had AUC of 0.81 (95% CI, .78–.82). In external validation, the models performed adequately although less robustly (AUC, 0.72 [95% CI, .70–.74]). CONCLUSIONS: Prediction models consisting of 3 routinely collected variables can accurately predict viral-only diarrhea in patients of all ages in Bangladesh and may help support efforts to reduce inappropriate antibiotic use.