Validity and internal consistency of four scales in patients with TMD: PHQ8, GAD7, PHQ15 and JFLS20

Objectives: The aim of this cross-sectional study was to explore the structural validity and internal consistency reliability of General Anxiety Disorder-7, Patient Health Questionnaire-8, 15 and Jaw Functional Limitation Scale-20 in patients with chronic pain of temporomandibular disorders.

Materials and methods: Validity and reliability were assessed in 129 patients diagnosed according to the diagnostic criteria for temporomandibular disorders. Structural validity was explored using factor analysis, and internal consistency by calculating Cronbach α.

Results: Confirmatory factor analysis revealed a suitable 2-factor model for Patient Health Questionnaire-8, with Cronbach α of 0.89, and 0.86. One and 2-factor models were suitable for General Anxiety Disorder-7, with overall Cronbach α of 0.93 for the 1-factor model, and 0.91 and 0.84 for both factors in a 2-factor model. A 4-factor solution was appropriate for Patient Health Questionnaire-15, with Cronbach α of 0.72, 0.57, 0.71 and 0.73 for each factor separately. Exploratory factor analysis was conducted to explore the factor structure of Jaw Functional Limitation Scale 20, and a 3-factor solution was appropriate.

Conclusions: This study provides positive evidence of structural validity and internal consistency of these questionnaires in patients with pain of temporomandibular disorders. However, additional testing is required to explore further psychometric properties.