To be or not to B27 positive: implications for the phenotypes of axial spondyloarthritis outcomes. Data from a large multiracial cohort from the Brazilian Registry of Spondyloarthritis.

BACKGROUND: There is a remarkable variability in the frequency of HLA-B27 positivity in patients with spondyloarthritis (SpA), which may be associated with different clinical presentations worldwide. However, there is a lack of data considering ethnicity and sex on the evaluation of the main clinical and prognostic outcomes in mixed-race populations. The aim of this study was to evaluate the frequency of HLA-B27 and its correlation with disease parameters in a large population of patients from the Brazilian Registry of Spondyloarthritis (RBE). METHODS: The RBE is a multicenter, observational, prospective cohort that enrolled patients with SpA from 46 centers representing all five geographic regions of Brazil. The inclusion criteria were as follow: (1) diagnosis of axSpA by an expert rheumatologist; (2) age ≥18 years; (3) classification according to ASAS axial. The following data were collected via a standardized protocol: demographic data, disease parameters and treatment historical. RESULTS: A total of 1096 patients were included, with 73.4% HLA-B27 positivity and a mean age of 44.4 (±13.2) years. Positive HLA-B27 was significantly associated with male sex, earlier age at disease onset and diagnosis, uveitis, and family history of SpA. Conversely, negative HLA-B27 was associated with psoriasis, higher peripheral involvement and disease activity, worse quality of life and mobility. CONCLUSIONS: Our data showed that HLA-B27 positivity was associated with a classic axSpA pattern quite similar to that of Caucasian axSpA patients around the world. Furthermore, its absence was associated with peripheral manifestations and worse outcomes, suggesting a relevant phenotypic difference in a highly miscegenated population.

Validation and clinical interpretability of PsAID - psoriatic arthritis impact of disease.

BACKGROUND: Psoriatic arthritis (PsA) is a chronic inflammatory disease of widely varying presentation, which determines functional and psychological impairment, with a high negative impact on patients' quality of life. Therefore, knowing the patient's perception of their health status is of fundamental importance for understanding the real impact of PsA. Given this context, the European League Against Rheumatism (EULAR) recently developed the Psoriatic Arthritis Impact of Disease (PsAID) - instrument to specifically assess the impact of PsA for the patient. OBJECTIVE: Validate the brazilian portuguese version of PsAID-12 (Psoriatic Arthritis Impact of Disease) and to verify its interpretability in clinical practice, through its relation with measures of psoriatic arthritis activity. METHODS: A multicenter cross-sectional study, which recruited 160 patients, who met the Classification criteria for Psoriatic Arthritis (CASPAR), in six Brazilian centers of rheumatology. Reliability was assessed by Cronbach's alpha coefficient and by the intraclass correlation coefficient (ICC). The construct validity was evaluated by exploratory factorial analysis and also by Spearman correlation with other PROMs and measures of disease activity evaluation. RESULTS: Of the total number of participants, 50% were female, with a mean age (SD) of 54.0 ± 11.2 years; 68% had only peripheral arthritis and 32% had pure or mixed axial involvement. The majority (67.7%) of the patients were using biological treatment. The reliability of internal consistency (alpha-Cronbach = 0.93) and test-retest (ICC = 0.996) were good. Factor analysis revealed two factors, named physical and psychosocial, which included the skin evaluation item. PsAID-12 correlated significantly with other PROMs, demonstrating good construct validity. PsAID-12 was also significantly associated with the disease activity assessment instruments (DAS28-ESR, ASDAS, and BASDAI) and the MDA status: "Minimum Disease Activity". Fibromyalgia did not significantly affect the final PsAID-12 score. CONCLUSION: The brazilian version of PsAID-12 has been shown to be a reliable and valid measure of the impact of the disease in patients with psoriatic arthritis. Moreover, it associated significantly with the scores of disease activity assessment.