Longitudinal validation of the Fear of COVID-19 Scale in a nationwide United States sample: An item response theory model across three inflection points of the pandemic.

ABSTRACT

The COVID-19 pandemic's global emergence/spread caused widespread fear. Measurement/tracking of COVID-19 fear could facilitate remediation. Despite the Fear of COVID-19 Scale (FCV-19S)'s validation in multiple languages/countries, nationwide United States (U.S.) studies are scarce. Cross-sectional classical test theory-based validation studies predominate. Our longitudinal study sampled respondents to a 3-wave, nationwide, online survey. We calibrated the FCV-19S using a unidimensional graded response model. Item/scale monotonicity, discrimination, informativeness, goodness-of-fit, criterion validity, internal consistency, and test-retest reliability were assessed. Items 7, 6, and 3 consistently displayed very high discrimination. Other items had moderate-to-high discrimination. Items 3, 6, and 7 were most (items 1 and 5 the least) informative. [Correction added on 18 May 2023, after first online publication In the preceding sentence, the term 'items one-fifth least' has been changed to 'items 1 and 5 the least'.] Item scalability was 0.62-0.69; full-scale scalability 0.65-0.67. Ordinal reliability coefficient was 0.94; test-retest intraclass correlation coefficient 0.84. Positive correlations with posttraumatic stress/anxiety/depression, and negative correlations with emotional stability/resilience supported convergent/divergent validity. The FCV-19S validly/reliably captures temporal variation in COVID-19 fear across the U.S.