Analysis of Test-Retest Reliability, Construct Validity, and Internal Consistency of the Brazilian Version of the Pelvic Girdle Questionnaire.

OBJECTIVE: The purpose of this study was to evaluate test-retest reliability, construct validity, and internal consistency of the Brazilian version of the Pelvic Girdle Questionnaire (PGQ-Brazil).

METHODS: Analysis of the measurement properties was carried out in 4 steps. Step 1 was the pilot study, on which basis 4 hypotheses were formulated. These hypotheses were tested during the next step (construct validity, step 2) by completion of the questionnaire by the 2 groups (in pain [n = 105] and not in pain [n = 52]). For implementation of the PGQ-Brazil in the group with pain, we calculated the internal consistency (step 3) and, 7 days later, test-retest reliability (step 4) by re-application of the instrument in this group.

RESULTS: First, the PGQ-Brazil was able to discriminate between these groups (construct validity). Second, test-retest reliability (intraclass correlation coefficients for Activities subscale [0.97 with 95% confidence interval of 0.95-0.98] and Symptoms subscale [0.98 with 95% confidence interval of 0.97-0.98] and κ coefficient between 0.50 and 0.89 for the items) was found to be good; the Bland-Altman test indicated satisfactory agreement. The Rasch analysis indicated good internal consistency, and the instrument's ability to divide the participants into at least 3 levels of skills was confirmed. In contrast, a ceiling effect was observed, as 24% of pregnant women exhibited skills superior to what the PGQ-Brazil could evaluate.

CONCLUSIONS: The PGQ-Brazil had good internal consistency, test-retest reliability, and construct validity in assessment of limitations in activities and symptoms of pregnant women with pelvic girdle pain.