Introduction: Obesity is a chronic noncommunicable disease, defined by a body mass index over 30 kg/m2. Its impact is not restricted to its association with higher risks of mortality and morbidity from other noncommunicable diseases, but also with a decrease in quality of life (QoL). There are several tools to assess QoL, from generic health-related tools to obesity-related specific ones. However, to assess QoL in patients undergoing bariatric surgery, only the Bariatric Analysis and Reporting Outcome System was available, which presented some significant problems. Therefore, the Bariatric Quality of Life (BQL) Index was developed. The aim of this study was the validation and cultural adaptation of the BQL Index for European Portuguese.
Methods: A cross-sectional study was conducted, with the presentation of two questionnaires to the participants: BQL Index and EQ-5D-3L (European Quality of Life 5 Dimensions and 3 Level) Index. Direct translation followed reviewing, back-translation, comparison, and pilot testing were performed. Retest was done six months after the baseline. The following psychometric properties were assessed: convergent validity using the Spearman r correlation coefficient between BQL Index and EQ-5D-3L Index; internal consistency based on Cronbach alpha coefficient; and reproducibility between test and retest through Spearman r correlation coefficient and intraclass correlation coefficient (ICC).
Results: A total of 260 participants were included, the mean age was 45 ± 10 years old, the mean body mass index was 44 ± 6.5 kg/m2 and 78% were females. The most frequent obesity-related comorbidities were osteoarticular disease (69%), anxiety/depression (60%), and hypertension (54%). The most common eating patterns were volume eater (67%) and sweet eater (62%). Quality of Life scores were 41.3 ± 9.3 for the BQL Index, 0.35 ± 0.19 for the EQ-5D-3L Index and 55.7 ± 19.8 for the EQ-5D-3L VAS. The translation yielded good convergent validity (r = 0.62), good internal consistency (alpha = 0.94), and good reproducibility (r = 0.62 and ICC = 0.79).
Conclusion: Our translation exhibited good parametric properties, with validity within the original BQL values, higher internal consistency, and good reproducibility.

Click here for the full paper.