The Short Form of the Fonseca Anamnestic Index (SFAI) is a simple and quick questionnaire used for screening temporomandibular disorders (TMDs). The present study aimed to validate the Spanish version of the SFAI in patients with TMDs. The study sample comprised 112 subjects (50 TMDs and 52 controls). Test-retest reliability, factorial validity, internal consistency, concurrent validity, and the SFAI's ability to discriminate between TMDs subjects and healthy controls were analyzed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD protocol) as the reference. Factor analysis showed a single factor that explained 63% of the total variance. Cronbach's alpha was 0.849. The reliability of the items measured with the Kappa index showed values from 0.767 to 0.888. Test-retest reliability was substantial (intraclass correlation coefficient = 0.837). The total SFAI score showed a significant correlation with orofacial pain, vertigo, and neck disability measurements. For a cut-off point of >10 points, the SFAI showed a sensitivity of 78% and specificity of 78.85% at differentiating between TMDs patients and healthy subjects, with an area under the curve (AUC) of 0.852. The Spanish version of the SFAI is a valid and reliable instrument for diagnosing people with TMDs and shows generally good psychometric properties.
Keywords: reproducibility of results; surveys and questionnaires; temporomandibular joint syndrome; validation study.