The prevalence of rheumatoid arthritis in Split-Dalmatia County in southern Croatia is 0.24

Association of HLA-DRB1 alleles with rheumatoid arthritis in Split-Dalmatia County in southern Croatia

OBJECTIVE

The aim of this study was to investigate the distribution of HLA-DRB1 alleles in patients with rheumatoid arthritis (RA) in the Sinj Region (SR) and the rest of the Split-Dalmatia County (SDC) in Croatia and to determine their relationship with disease severity.

METHODS

A total of 74 RA patients and 80 healthy controls from the SR, and 74 RA patients and 80 healthy controls from the rest of the SDC were genotyped using sequence-specific oligonucleotide primed PCR. High-resolution typing of HLA-DRB1*04 alleles was performed using the single specific primed polymerase chain reaction (PCR-SSP) method. Serum anti-CCP, rheumatoid factor, C‑reactive protein, and erythrocyte sedimentation rate were measured in all RA patients, whereas disease activity was assessed by DAS-28 and functional status by the Health Assessment Questionnaire Disability Index.

RESULTS

The HLA-DRB1*04 allele was more frequent in patients with RA from the SR than that in patients from the rest of the SDC (18.2% vs. 9.5%; P = 0.014), whereas the HLA-DRB1*15 allele was more frequent in patients with RA from the rest of the SDC than in patients from the SR (16.2% vs. 7.4%; P = 0.010). Shared epitope (SE) positive patients from the SR had significantly higher serum anti-CCP and RF antibody levels (P = 0.014 and P = 0.004, respectively), higher disease activity (P = 0.043), and worse functional status (P < 0.001), than SE-positive patients from the rest of the SDC.

CONCLUSION

The observed higher incidence of more severe forms of RA in the SR in comparison to the rest of the SDC might be associated with the higher incidence of HLA-DRB1*04 allele in the SR.

Prevalence of rheumatoid arthritis in South America: a systematic review and meta-analysis

Rheumatoid arthritis (RA) is among the most prevalent chronic autoimmune and inflammatory diseases worldwide. The aim of this study was to establish a pooled estimate of the RA prevalence in South America by means of a meta-analysis of the available epidemiologic studies. Systematic searches in PubMed, Lilacs, SciELO, Scopus, and Web of Science databases (updated May 2019) were done followed by a systematic grey literature search to identify original research articles and reports, published after 2000, providing data of RA prevalence in any South American country. Proportion meta-analysis of weighted pooled was performed, with between-trial heterogeneity assessed by the inconsistency relative index. Sensitivity analyses and sub-group analyses were also done. A total of 25 articles, representing 27 population-based studies were included. Pooled prevalence of RA resulted in 0.48% with 591,981 cases in a population of 114,537,812 individuals (I2=99%). Brazil and Colombia presented the lowest rates of RA prevalence 0.22%, and 0.24%, respectively. RA prevalence in indigenous population was higher 1.45%, and studies using COPCORD method reported also the highest rates 1.07%.