The Minimal Important Difference (MID) as a criterion in evaluating the clinical significance of changes in the quality of life of orthognathic patients

Abstract

Abstract: The Minimal Important Difference (MID) represents the smallest change patients perceive in their health status. It is a convenient criterion for evaluating the clinical significance of changes in Health-Related Quality of Life (HRQoL). This literature review aims at presenting a critical overview of the MID concept, the methods used to evaluate whether a change in HRQoL is lower or higher than the MID, and, finally, to research* the range of changes suggesting clinically significant differences in the HRQoL of orthognathic patients in the relevant literature. According to the modern scientific literature, the MID may help evaluate the clinical significance of changes measured in different trials from the patient’s perspective. Particularly in the case of patients undergoing orthognathic surgery, it could contribute to an in-depth analysis of the resulting benefits, understanding the process more holistically, and taking the most appropriate treatment decisions. To determine MID, the use of a combination of statistics-based methods, such as the Standard Error of Measurement (SEM), and methods based on anchors is recommended. Specifically, with respect to the HRQoL SF-36v1 (Short-Form-36 Health Survey version 1), the SIP (Sickness Impact Profile), the WHOQL-BREF (World Health Organization Quality of Life-BREF), the OHIP-14 (Oral Health Impact Profile-14) and the OQoLQ (Orthognathic Quality of Life Questionnaire), which have been used in the prospective evaluation of HRQoL in orthognathic patients, no relevant available MID values were found. A further systematic study of the MID concept in the quality of life of patients undergoing orthognathic surgery could help achieve a more comprehensive record of the impact of this treatment procedure on the patients’ physical and psychosocial well being.