Measuring dengue illness intensity: Development and content validity of the dengue virus daily diary (DENV-DD).

Dengue is the most common viral infection transmitted to humans by mosquitos, and affects an estimated 50­60 million individuals globally per year. However, there are few resources for understanding and capturing the patient experience of dengue throughout illness. Most research studies are based on healthcare provider assessment, which lack consistency in terms of assessment time points and the signs/symptoms assessed. The 'Dengue Illness Index Report Card (DII-RC)' was used as a foundation to create the new 'Dengue Virus Daily Diary (DENV-DD)' to better capture the patient experience of symptom intensity and dengue disease burden for the duration of illness. Forty-eight individuals and caregivers of younger children from Peru and Ecuador who recently had symptomatic dengue were interviewed to understand the patient experience over the time of illness and to test whether the DENV-DD is understood by patients and caregivers and includes all relevant and important signs/symptoms and health-related quality of life impacts. Nine individuals with active dengue infection also completed the DENV-DD daily for 28-days as part of a clinical study. We found that > 70% of patients experienced fever, headache, body ache/pain, loss of appetite and body weakness. The DENV-DD instructions, questions and response option(s) were well understood, feasible to complete and the concepts assessed by the DENV-DD were relevant to the dengue experience. Our study adds to the understanding of the dengue illness experience and supports the DENV-DD for use in future dengue studies as an assessment of signs/symptoms throughout the duration of illness.