Translation, Cross-Cultural Adaptation, and Validation of the Dyspnea Index Into Brazilian Portuguese

Objective: To perform the cross-cultural adaptation and validation of the Dyspnea Index (DI) in Brazilian Portuguese (BP). Methods: This validation study followed the Consensus-based Standards for the Selection of Health Measurement Instruments recommendations. The translation was conducted in five stages: translation, synthesis, back translation, committee review, and pretest performance. The validation comprised the following steps: (a) construct validity, (b) criterion validity, (c) internal consistency, and (d) reproducibility. The study included 86 adults with dyspnea complaints in the dyspnea group (DG) and 46 adults without dyspnea complaints in the control group (CG), matched for age and gender. All participants completed the DI, the Vocal Handicap Index-10, and the Laryngeal Hypersensitivity Questionnaire. The DG completed the DI a second time. Results: The item “the change in weather affects my breathing problem” did not reach agreement in the DI translation and required adjustments in the synthesis stage. In the pretest stage, all items had a lower proportion of “not applicable” responses, with P < 0.001. Construct validity confirmed a 10-item, one-factor structure. Internal consistency achieved a Cronbach's alpha of 0.941 and reproducibility yielded an intraclass correlation coefficient of 0.765. For criterion validity, the DI significantly distinguished the DG from the CG with higher scores (U = 434.5; P < 0.001) and showed parallel correlations with perceived vocal handicap (r = 0.232; P = 0.032) and laryngeal sensations (r = 0.400; P = 0.001). Conclusion: The DI was cross-culturally adapted and validated in BP as the Índice de Dispneia. It has a 10-item, one-factor structure and is considered valid and reliable for self-administration in BP speakers.