Electronic supplementary material
The online version of this article (doi:10.1186/1477-7525-10-128) contains supplementary material, which is available to authorized users.
The authors declare that they have no competing interests.
FZ and MK conceptualized the project and developed the statistical analysis plan (SAP). The SAP was reviewed by all authors. MS, BL, ML and the members of the TRI database study contributed to data collection. FZ analyzed the data and drafted the manuscript. All authors contributed to the interpretation of data and to the final version of the manuscript. All authors read and approved the final manuscript.
Tinnitus research in an international context requires standardized and validated questionnaires in different languages. The aim of the present set of analyses was the reassessment of basic psychometric properties according to classical test theory of self-report instruments that are being used within the multicentre Tinnitus Research Initiative (TRI) database project.
1318 patients of the TRI Database were eligible for the analyses. The basic psychometric properties reliability, validity, and sensitivity of Tinnitus Handicap Inventory (THI), Tinnitus Questionnaire (TQ) and Tinnitus Beeinträchtigungs Fragebogen (i.e., Tinnitus Impairment Questionnaire, TBF-12) were assessed by the use of Cronbach’s alpha, corrected item-total correlations, correlation coefficients and standardized response means.
Throughout the languages, all questionnaires showed high internal consistencies (Cronbach’s alpha > 0.79) and solid item-total correlations, as well as high correlations among themselves (around 0.8) and in combination with the self-reported tinnitus severity. However, some paradoxical correlations between individual items of the TBF-12, constructed as a shortform of the THI, and the corresponding THI-items were seen. Standardized Response Means (SRM) were low if tinnitus did not change, and between 0.3 and 1.09 for improved or worsened tinnitus complaints, indicating the sensitivity of the measures.
All investigated instruments have high internal consistency, high convergence and discriminant validity and good change sensitivity in an unselected large multinational clinical sample and thus appear appropriate to evaluate the effects of tinnitus treatments in a cross-cultural context.