Linguistic validation and reliability of the Brazilian Portuguese version of the Composite Autonomic Symptom Score 31 (COMPASS 31)

The Composite Autonomic Symptom Score 31 (COMPASS-31) is a validated self-report questionnaire designed to assess autonomic symptoms across six domains. A Brazilian Portuguese version has not yet been formally validated. Following a standardized Mayo Clinic linguistic validation protocol, the COMPASS-31 was translated into Brazilian Portuguese. Twenty-one patients with disorders associated with autonomic symptoms and nine healthy controls completed both the English and Portuguese versions in randomized order, with a six-week interval between administrations. Reliability was assessed using kappa coefficients and Bland–Altman analysis. Validity was evaluated by comparing scores between patients and controls and by correlating the Portuguese and English versions. The Brazilian Portuguese version of the COMPASS-31 demonstrated good test–retest reliability and a strong correlation with the original English version (r = 0.784, p < 0.0001). Patients exhibited significantly higher total scores than healthy controls. Bland–Altman analysis showed good agreement, with 93.4% of values falling within the limits of agreement. The Brazilian Portuguese version of the COMPASS-31 is a valid and reliable instrument for assessing autonomic symptoms in both clinical and research settings.