Italian validation of the Insomnia Catastrophizing Scale (ICS): An instrument to assess insomnia-specific catastrophizing thoughts

Introduction: Several instruments have been developed and validated to investigate insomnia-specific cognitions. The Insomnia Catastrophizing Scale (ICS) is a self-report questionnaire evaluating catastrophizing thoughts related to nighttime symptoms (ICS-N) and daytime impairment (ICS-D) of insomnia. The aim of the present study was to assess the psychometric properties of the Italian version of the ICS. Methods: An Italian sample of 435 university students (Mean age=23.5 ± 4.68; %F=76.5) completed the ICS together with the Insomnia Severity Index (ISI). Confirmatory factor analyses (CFA) of the ICS-N and the ICS-D were conducted using MPLUS7 software. Model parameters were estimated using the maximum likelihood (ML) estimation method, and the quality of the measurement model was visually examined through the fit indices estimates of Tucker-Lewis index (TLI), comparative fit index (CFI), and standardized root mean square residual (SRMR). Cronbach’s alpha coefficient for each scale was estimated to evaluate the internal consistency of items. Finally, correlations with ISI were performed to evaluate convergent validity of ICS scales. Results: The CFA showed that the one-factor model fit the data well both for the ICS-N (χ2(44)=366.349, p<.001; CFI=.901, SRMR=.048) and the ICS-D (χ2(9)=81.688, p<.001; CFI=.906; SRMR=.022). In both cases, the items loaded significantly on their latent factor (>.65). Chronbach’s alpha was .93 for the ICS-N and .94 for ICS-D. Both ICS-N and ICS-D correlated with ISI (r=.717, p=.001 for ICS-N and r=.615, p=.001 for ICS-D). Conclusion: CFA confirmed the presence of one-factor structure for both the ICS-N and the ICS-D. The two scales also showed to be reliable at a satisfactory level. Finally, both the scales correlated with insomnia severity, supporting the concurrent validity of the two scales. Support (If Any): None to report.