RESUMEN
BACKGROUND: Clinically evident interstitial lung disease (ILD) affects 10%-42% of RA patients with prognostic implications. The aim of this study was to discern which factors are associated with the presence of ILD in RA patients and to develop a score that could help to stratify the risk of having ILD in RA patients. METHODS: Case-control study. We included RA patients recruited from ILD and rheumatology clinics. We retrieved the following data: gender, age, presence of extra articular manifestations, disease activity scores, antibodies status, ESR, and medication use. Multivariate logistic regression was performed. A risk indicator score was developed. RESULTS: Of 118 patients included in this study, 52 (44%) had RA-ILD (cases) and 66 (56%) had RA without ILD (controls). Twenty-six patients were male (22%), the mean age was 56.6±15.6 years. Five variables were significantly associated with the presence of ILD: male gender, smoking, extraarticular manifestations, a CDAI score>28, and ESR>80mm/h. The AUC of the final model curve was 0.86 (95%CI 0.79-0.92). Two potential cut-off points of the risk indicator score were chosen: a value of 2 points showed a sensitivity of 90.38% and a specificity of 63.64%, while a value of 4 points showed a sensitivity of 51.9% and a specificity of 90.9%. CONCLUSION: This study identified risk factors that could help identify which RA patients are at risk of having ILD through the development of a risk indicator score. This score needs to be validated in an independent cohort.
RESUMEN
Patients with rheumatoid arthritis (RA) or undifferentiated arthritis (UA) in the CONAART database (Argentine Consortium for Early Arthritis) were assessed for genetic risk factors for RA, specifically for HLA-DRB1 alleles and the PTPN22 rs2476601 polymorphism associated with progression to RA. This is a case-control study. Blood samples were obtained to determine HLA-DRB1 genotypes by PCR-SSO Luminex and PTPN22 (rs2476601) polymorphism by allelic discrimination. A control group of individuals from the general Argentinian population were obtained from the national register of cadaveric organ donors. A total of 1859 individuals were included in this analysis: 399 patients from the CONAART database (347 patients with RA at study end and 52 patients with UA at study end, mean follow-up time 25 ± 18 months) and 1460 individuals from the general Argentinian population. Compared with the controls, the HLA-DRB1*04 and DRB1*09 alleles were more commonly detected in patients with RA diagnosis (OR (95% CI) 2.23 (1.74-2.85) and 1.89 (1.26-2.81)) respectively. Both patients with UA and the general population showed higher frequency of DRB1*07, DRB1*11 and DRB1*15 alleles than patients with RA. PTPN22 rs2476601 polymorphism frequency was higher in RA and UA vs the general population; however, this was significantly different only for RA vs control group (OR [95% CI] = 1.81 [1.10-3.02], P = 0.018. HLA-DRB1 typing and PTPN22 allelic discrimination could distinguish between patients with UA, patients with early RA, and the general population in Argentina. This is the first study of HLA-DRB1 alleles and PTPN22 polymorphism associations with progression to early RA in an Argentinian population.
