Date of Conferral
Primary efficacy endpoints for interventional products targeting travelers’ diarrhea (TD) prevention have been predominately based on stool frequency. However, reliance on stool-based endpoints alone may obscure potentially meaningful differences in illness profiles. A single, standardized scoring system optimized for use in adult travelers is needed to accurately measure TD severity and enable more robust estimates of treatment or intervention effectiveness. The purpose of this quantitative secondary data analysis was to describe the variability in TD signs and symptoms across traditional severity metrics such as stool output, identify which symptoms were significantly associated with a negative impact on activity, and determine whether a TD scoring system that considers other symptomology could be optimized for use in future studies using the IRT and CTT frameworks. Data were obtained from two interventional studies: TrEAT TD, a multi-site TD treatment trial, and OEV-118—a placebo-controlled ETEC vaccine efficacy trial in travelers. Correlation, regression and multiple correspondence analyses were performed across multiple signs and symptoms to assess impact on activity and a TD severity score was established. Conclusions were (a) the new TD score significantly benefits the estimation of impact on activity over any individual sign or symptom, and (b) there was a benefit to reduction in overall TD disease severity when applied to a previously conducted vaccine efficacy trial. The use of a single optimized scoring system may better capture illness severity than commonly utilized metrics and moves the field towards current recommendations for TD management. Additionally, the use of the TD severity score may be an improved efficacy metric than stool frequency for future vaccine trials.