Validity and reliability of the COVID-19 symptom index, an instrument evaluating severity of general and otolaryngological symptoms

Abstract

BACKGROUND: There is no clinical instrument evaluating symptoms of COVID-19. OBJECTIVE: To develop a clinical instrument for evaluating symptoms of COVID-19 mild-to-moderate forms. METHODS: COVID-19 patients were recruited from EpiCURA Hospital (Belgium). They completed the COVID-19 Symptom Index (CSI) twice to assess the test-retest reliability. The internal consistency was evaluated with Cronbach's alpha. CSI was completed by healthy subjects to assess the internal validity. Patients completed CSI 6 weeks after the COVID-19 resolution to evaluate the responsiveness to change. RESULTS: < .001), supporting a high external validity. COVID-19 patients reported significant higher CSI score than healthy individuals, suggesting an adequate internal validity. The mean CSI significantly decreased after the COVID-19 resolution, supporting a high responsiveness to change property. CONCLUSION AND SIGNIFICANCE: The CSI is a reliable and valid patient reported outcome questionnaire for the evaluation of symptom severity of COVID-19 patients.