Further validation of the Gothenburg Trismus Questionnaire (GTQ).

Abstract

This study aimed to update and, if necessary, revise the Gothenburg Trismus Questionnaire (GTQ), the only existing trismus-specific questionnaire, and retest its psychometric properties. Semi-structured interviews were performed with 10 trismus patients of which 5 had head and neck cancer (HNC) and 5 suffered from benign temporomandibular disorders. Trismus was defined as a maximal incisal opening of ≤ 35mm. An expert panel discussed and revised the GTQ based on interview information, expertise knowledge and the original questionnaire. The revised questionnaire was then tested in a study sample consisting of benign jaw-related conditions (n = 26), patients treated for HNC (n = 90) and an age- and gender-matched control group with no trismus (n = 116). The revised version of the GTQ (GTQ 2) was well accepted by patients. The original three domains continued to show high internal consistency (Cronbach’s alpha 0.74–0.94) and construct validity. Two dually posed single items were split into four questions and the wording was altered in another three items. Moreover, a new domain (Facial pain) was identified, which had excellent internal consistency (α = 0.96) and good construct validity. The revision of the original Gothenburg Trismus Questionnaire (GTQ 1) with inclusion of patient-input, resulted in splitting of ambiguous items, identifying a fourth domain named Facial pain and the recall time shortened for some items. Additionally, the remaining domains and items were re-confirmed as strong in the psychometric analysis. Henceforth, the new version, GTQ 2 should be used.