Validation of the Brazilian-Portuguese Version of the Gesture Behavior Test for Patients with Non-Specific Chronic Low Back Pain
OBJECTIVE
To develop a Brazilian version of the gesture behavior test (GBT) for patients with chronic low back pain.


METHODS
Translation of GBT into Portuguese was performed by a rheumatologist fluent in the language of origin (French) and skilled in the validation of questionnaires. This translated version was back-translated into French by a native-speaking teacher of the language. The two translators then created a final consensual version in Portuguese. Cultural adaptation was carried out by two rheumatologists, one educated patient and the native-speaking French teacher. Thirty patients with chronic low back pain and fifteen healthcare professionals involved in the education of patients with low back pain through back schools (gold-standard) were evaluated. Reproducibility was initially tested by two observers (inter-observer); the procedures were also videotaped for later evaluation by one of the observers (intra-observer). For construct validation, we compared patients' scores against the scores of the healthcare professionals.


RESULTS
Modifications were made to the GBT for cultural reasons. The Spearman's correlation coefficient and the intra-class coefficient, which was employed to measure reproducibility, ranged between 0.87 and 0.99 and 0.94 to 0.99, respectively (p < 0.01). With regard to validation, the Mann-Whitney test revealed a significant difference (p < 0.01) between the averages for healthcare professionals (26.60; SD 2.79) and patients (16.30; SD 6.39). There was a positive correlation between the GBT score and the score on the Roland Morris Disability Questionnaire (r= 0.47).


CONCLUSIONS
The Brazilian version of the GBT proved to be a reproducible and valid instrument. In addition, according to the questionnaire results, more disabled patients exhibited more protective gesture behavior related to low-back.