Development of a condition-specific quality of life measure for patients with dentofacial deformity: II. Validity and responsiveness testing

The assessment of quality of life is becoming increasingly important in dentistry. This may be measured using two groups of instruments: generic and condition-specific. Objectives: This paper describes the processes of validity and responsiveness testing of a condition-specific quality of life measure for patients who present with severe dentofacial deformity requesting orthognathic treatment (the so-called Orthognathic Quality of Life Questionnaire). The development of the instrument is described in a previous paper. Method: The OQLQ was tested for validity using a visual analogue scale and also the Short-Form 36 health survey questionnaire. Responsiveness was tested using longitudinal data obtained before, during and after orthognathic treatment. Results and Conclusions: The OQLQ shows good evidence of validity and responsiveness. This, together with previous evidence of good reliability, suggests that the instrument may prove useful in both clinical trials and in quality assurance.