Development and validation of the Gothenburg Trismus Questionnaire (GTQ).

OBJECTIVES

To develop and validate a comprehensive, self-administered questionnaire for patients with limited ability to open the mouth, trismus.

MATERIALS AND METHODS

We derived the Gothenburg Trismus Questionnaire (GTQ) from empirical evidence in the medical literature and interviews with medical experts as well as patients. The draft version was tested in a pilot study (n=18). Patients with a maximal incisal opening (MIO) of ⩽35mm were included. The study comprised patients with benign jaw-related conditions (n=51), patients treated for head and neck (H&N) cancer (n=78) and an age- and gender-matched control group without trismus (n=129).

RESULTS

The GTQ instrument was well accepted by the patients, with satisfactory compliance and low rates of missing items. After item reduction, due to items not being conceptually relevant and/or low factor loadings, the GTQ demonstrated high internal consistency (Cronbach's alpha 0.72-0.90), good construct validity and known-group validity.

CONCLUSION

We developed a trismus-specific self-administered questionnaire, the GTQ, that showed good psychometric properties. We suggest this questionnaire, that has clear clinical relevance, to be adopted and used in clinical practice and in research, acting as a screening tool as well as an endpoint in intervention and jaw physiotherapy/rehabilitation studies.