Construction and validation of an questionnaire for evaluating self-medication practised by patients with temporomandibular disorders.

Aims: Despite the fact that self-medication associated with temporomandibular disorders is clinically quite common and is considerably harmful, there is no instrument in the literature to assess this practice. The aim of this study was to construct and validate a questionnaire to study this important issue specifically.

Methods: After completing the literature review, semi-structured interviews, focus group and pretest, the first version of the instrument resulted in 62 questions. After face validity testing, pretest and the necessary corrections and changes, the instrument had 41 questions and was administered for validation to a sample of 110 patients diagnosed with TMD according to the RDC/TMD (1992) criteria.

Results: According to factor analysis, seven questions with loadings below 0.30 were removed, with the final version consisting of 34 questions. The analysis of internal consistency and temporal stability showed values of 0.844 for Cronbach's alpha coefficient and a Kappa coefficient of 0.810, respectively, indicating that the instrument presents sufficient reliability and reproducibility for its proposed objective. After validation, with the ultimate goal of classifying patients according to the degree/intensity of self-medication, a classification was proposed that allowed the discrimination of results into three distinct groups regarding self-medication exposure: mild, moderate or severe, based on the self-medication raw point score.

Conclusion: The results of the instrument validation process showed that it has suitable properties for evaluating the practice of self-medication in patients with TMD.