What is the minimal important difference of pain intensity, mandibular function, and headache impact in patients with temporomandibular disorders? Clinical significance analysis of a randomized controlled trial

Background: There are insufficient studies providing Minimal Clinically Important Difference (MCID) for outcomes related to tempommandibular disorders (TMD). Objectives: (1) To provide the MCID of outcomes related to TMD using the Global Rating of Change Scale (GRCS) as an anchor. (2) To verify which outcomes can predict a moderate or large response to the treatment. Study design: Secondary analysis of a randomized controlled trial in subjects with TMD. Methods: Sixty-one women with TMD were divided into intervention and control groups. Visual Analogue Scale (VAS), Headache Impact Test (HIT-6), pressure pain thresholds (PPTs) of masticatory muscles, Mandibular Function Impairment Questionnaire (MFIQ), and Craniocervical Flexion Test (CCFT) were collected at baseline and 5-weeks follow-up. Results: Participants were divided based on their response to the treatment, according to the GRCS. MCID values were provided for subjects that moderately or largely improved to the treatment. MCID was between 0 and 1.90 for omfacial pain, around 2 points for the MFIQ, between 3 and 6.26 points for the HIT-6, around 0.2 kg/cm(2) for the PPTs on masticatory muscles, around 2.5 mm for MMO and between 60 and 68 points for CCFT. Orofacial pain and HIT-6 were the most discriminative variables at determining whether patients would largely/moderately improve or would not improve after treatment. Conclusions: The values of MCID could be used as guidance for both clinical practice and research. Pain intensity and headache impact were the most predictive outcomes for improvement of the general health status of women with TMD.