Abstract
A confirmatory factor analysis (CFA) of the Tinnitus Impact Questionnaire (TIQ) was performed. In contrast to commonly used tinnitus questionnaires, the TIQ is intended solely to assess the impact of tinnitus by not including items related to hearing loss or tinnitus loudness. This was a psychometric study based on a retrospective cross-sectional analysis of clinical data. Data were available for 155 new patients who had attended a tinnitus and hyperacusis clinic in the UK within a five-month period and had completed the TIQ. The mean age was 54 years (standard deviation = 14 years). The TIQ demonstrated good internal consistency, with Cronbach's α = 0.84 and McDonald's ω = 0.89. CFA showed that two items of the TIQ had low factor loadings for both one-factor and two-factor models and their scores showed low correlations with scores for other items. Bi-factor analysis gave a better fit, indicated by a relative chi-square (χ2) of 18.5, a Root-Mean Square Error of Approximation (RMSEA) of 0.103, a Comparative Fit Index (CFI) of 0.97, a Tucker Lewis Index (TLI) of 0.92, and a Standardized Root-Mean Residual (SPMR) of 0.038. Total TIQ scores were moderately correlated with scores for the Visual Analogue Scale of effect of tinnitus on life and the Screening for Anxiety and Depression-Tinnitus questionnaire, supporting the convergent validity of the TIQ. The TIQ score was not correlated with the pure-tone average hearing threshold, indicating discriminant validity. A multiple-causes multiple-indicator (MIMIC) model showed no influences of age, gender or hearing status on TIQ item scores. The TIQ is an internally consistent tool. CFA suggests a bi-factor model with sufficient unidimensionality to support the use of the overall TIQ score for assessing the impact of tinnitus. TIQ scores are distinct from the impact of hearing impairment among patients who have tinnitus combined with hearing loss.