Cross-Cultural Adaption and Psychometric Evaluation of the German Craniofacial Pain and Disability Inventory (CF-PDI)

BACKGROUND: The Craniofacial Pain and Disability Inventory (CF-PDI) is a cross-culturally adapted instrument designed from a biopsychosocial perspective to measure pain, disability, and function in orofacial head and neck pain with shown psychometric properties; however, the German cross-cultural adaption is lacking. OBJECTIVES: To carry out a transcultural translation of CF-PDI into German and assess its psychometric properties in patients with painful temporomandibular disorders (TMD) with respect to construct and clinical validity, internal consistency and reproducibility. STUDY DESIGN: Multicenter, prospective, cross-sectional design. SETTING: Patients (n = 398) were recruited from dental and physical therapy clinics in middle and south Germany. METHODS: Structural validity was assessed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). We investigated know-group validity by means of the scale’s potential to discriminate between affected and unaffected subjects. Multiple linear regression analysis was used to estimate convergent validity. We tested test-retest reliability by the intraclass correlation coefficient and the Internal consistency by Cronbach’s alpha, or each dimension separately, and the total score. Multiple linear regression analysis was used to estimate convergent validity. RESULTS: Two hundred forty-six heterogeneous chronic craniofacial pain patients and 152 patients without complaints were recruited from the middle and south of Germany. The German version CF-PDI-G presents 21 items, 4 factors, and adequate psychometric properties. The test-retest reliability and internal consistency of the CF-PDI-G were both excellent for the entire instrument and also for all sub-scales (intraclass correlation coefficient [ICC] > 0.90) except for the comorbidities and interference with work which was acceptable (ICC = 0.69). Standard error of the measurement (SEM) and minimal detectable change values are sufficiently low. Assessment of clinical validity shows good potential of discrimination and classification into categories “no,” “mild,” “moderate,” and “severe.” The multiple linear regression model showed a strong association between neck disability index, Visual Analog Scale, and anamnestic questionnaire (supporting the scale’s convergent validity). LIMITATIONS: Our sample has a higher prevalence of women and the sample was not recruited consecutively, which may lead to a biased estimation of psychometric properties. CONCLUSIONS: The CF-PDI-G represents valid and reliable instrument to assess pain and disability in patients with orofacial pain and headache suitable for research and clinical practice. KEY WORDS: Craniofacial pain, cross-cultural, disability, German version, headache, neck pain, psychometric validation, questionnaire, reliability, temporomandibular disorders