Williams V, DeMuro C, Finelli L, Qin S, Saretsky TL, Ma J, Lewis S, Phillips M, Osborne RH. Preliminary psychometric evaluation of the respiratory syncytial virus infection intensity impact questionnaire (RSV-IIIQ) in adults. Poster presented at the Virtual ISPOR EUR 2021; November 30, 2021. [abstract] Value Health. 2022 Jan 1; 25(1 Supplement):S234. doi: 10.1016/j.jval.2021.11.1144

OBJECTIVES: A new self-report tool, the RSV Infection Intensity Impact Questionnaire (RSV-iiiQ), was adapted from an existing influenza symptom instrument (Osborne et al, 2011) consistent with FDA patient-focused drug development draft guidance. The RSV-iiiQ includes 29 questions in four hypothesized subscales (Respiratory Symptoms/Systemic Symptoms/Daily Activity Impacts/Emotional Impacts). The study aim was to evaluate preliminary psychometric properties of the RSV-iiiQ.

METHODS: A web-based, repeated cross-sectional observational study was conducted over two consecutive days in a convenience sample of US participants from 2 clinics and 2 qualitative research facilities, with laboratory-confirmed RSV at various severities. Participants were recruited within 21 days of an RSV medical encounter. Data from 111 adults (mean 44 years;78.4% female) were analyzed. Participants completed the RSV-iiiQ, Patient Global Impression of Severity (PGIS) and Change (PGIC) questions, the Sheehan Disability Scale (SDS), and the EQ-5D-5L. Measurement structure, internal consistency, test-retest reliability, construct/discriminating validity, and responsiveness of the RSV-iiiQ scale scores were evaluated.

RESULTS: Four single-factor confirmatory factor analysis models showed high loadings (0.63-0.96) and acceptable fit (CFI>0.95, SRMR<0.60, RMSEA=0.102-0.142). Test-retest reliability (stable subset based on PGIC ratings) was satisfactory (ICC≥0.65), as was internal consistency (alphas≥ 0.86) for all scales. Moderate to strong correlations were observed between RSV-iiiQ scale scores and corresponding SDS and the EQ-5D-5L scores (|r|=0.34-0.76). The RSV-iiiQ discriminated well between participants with varying symptom severity, number of days since RSV diagnosis, and SDS scores. Despite short study duration, moderate (r=0.31-0.38) correlations were observed between all RSV-iiiQ subscale change scores (except for Systemic Symptoms) and PGIS change.

CONCLUSIONS: Initial findings show the RSV-iiiQ is reliable, related to other variables in expected ways, and importantly, the original psychometric structure was reproduced. Further studies are needed in the context of a future vaccine or treatment trial to determine the RSV-iiiQ’s responsiveness to change over longer follow-up periods and develop thresholds for meaningful score changes.

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