OBJECTIVES: Lacking established clinical trial assessments for monitoring severity of pediatric RSV, the PRESORSv6 was developed as a set of questionnaires to assess the severity of signs of RSV infection in children based on observations by the child’s caregiver and clinician. This study evaluated the structure, scoring, reliability, and validity of both questionnaires.

METHODS: 124 children aged ≤36 months hospitalized for treatment of RSV infection were enrolled in a prospective, multicenter observational study. Caregivers assessed PRESORSv6 ObsRO 3xDaily for 7 days; Clinicians completed ClinRO 2x daily during hospitalization for up to 7 days. Item-level responses were evaluated with inter-item correlations, confirmatory factor analyses (CFA), and item response theory (IRT) models. Descriptive statistics, internal consistency, inter-rater reliability (ClinRO only), construct validity (correlation with ReSViNET), and known-groups validity (based on global impression and clinical status assessments) were evaluated for summary scores.

RESULTS: CFA confirmed PRESORS measures 2 domains: Respiratory Signs/Symptoms and Illness Behavior (root mean square error of approximation < 0.08; comparative fit index and Tucker-Lewis Index > 0.95). IRT analyses were used to refine response scales and create summary scores reflecting these factors: Respiratory Signs/Symptoms, Illness Behavior, and Overall RSV Severity. Floor and ceiling effects were minimal. Acceptable internal consistency reliability (most had Cronbach’s α > 0.70) and convergent validity with ReSViNET total scores (r² > 0.30) were observed for the ClinRO and ObsRO summary scores. Mean score patterns across known groups were in the expected directions and intraclass correlation coefficients showed adequate interrater reliability (≥ 0.79) for the ClinRO Respiratory Symptom Severity and Overall RSV Severity summary scores.

CONCLUSIONS: PRESORSv6 ClinRO and ObsRO produce summary scores with acceptable internal consistency and known-groups validity. The ClinRO also demonstrated acceptable inter-rater reliability and convergent validity. Further development and use of PRESORS to monitor RSV severity in clinical trials is ongoing.