Abstract

Clinically relevant anti-carbamylated (anti-CarP) antibodies are detected in up to 45% of rheumatoid arthritis (RA) patients and are associated with severe radiological progression, higher disease activity, and significantly more disability when studied in early phases of arthritis.We aimed to determine the prevalence of anti-CarP antibodies in Mexican Hispanics with established RA and to assess their relationship with disease activity.A cohort study was conducted in 278 patients with established RA during an 18-month follow-up. We measured IgG/IgM/IgA rheumatoid factor (RF), IgG anticitrullinated protein antibodies (ACPA) and IgG/IgM/IgA anti-CarP antibodies using enzyme-linked immunosorbent assay (ELISA). For disease activity, we performed the 28-joint disease activity score with erythrocyte sedimentation rate (DAS28-ESR). Repeated measures one-way ANOVA was used to test the association between anti-CarP IgG antibody status and longitudinal DAS28-ESR scores. Patients were evaluated at baseline and at 6, 12, and 18 months during follow-up.Anti-CarP IgG antibodies were positive in 47.8% of patients and, accounting for all isotypes, in 9.5% of patients with negative RF and ACPA. Triple antibody positivity was present in 42.6% of patients in our sample. Anti-CarP IgG antibody positivity did not show statistically significant differences in mean DAS28-ESR when compared to anti-CarP IgG antibody negative patients at baseline, 6, 12 or 18 months.Anti-CarP IgG antibodies are present in almost 50% of RA patients and, accounting for all isotypes, in 9% of RF and ACPA negative patients. Anti-CarP IgG antibody positivity was not associated to a higher disease activity measured by DAS28-ESR in Hispanic patients with established RA.Shi J, Knevel R, Suwannalai P, Van Der Linden MP, Janssen GMC, Van Veelen PA, et al. Autoantibodies recognizing carbamylated proteins are present in sera of patients with rheumatoid arthritis and predict joint damage. Proc Natl Acad Sci U S A. 2011;108:17372–17377.Table 1.Anti-CarP antibody status by isotype in a cohort of 278 patients with established RA.Mean (SD)Antibody positivity,n (%)95% CIRF IgAa266.9 (460.5)155 (58.9)53.0 to 64.9RF IgMa406.8 (611.9)188 (71.5)66.0 to 77.0RF IgGa36.1 (249.6)44 (16.7)12.2 to 21.3ACPA IgGa191.01 (411.1)144 (54.8)48.7 to 60.8Anti-CarP IgAb212.9 (464.2)74 (26.6)21.4 to 31.8Anti-CarP IgMb381.6 (762)89 (32)26.5 to 37.5Anti-CarP IgGb227.5 (402.5)133 (47.8)41.9 to 53.8aData were available for 263 patients. Units are RU/mL. bData were available for 278 patients. Units are AU/mL. RF, rheumatoid factor; ACPA, anticitrullinated protein antibodies; Anti-CarP, anti-carbamylated protein antibodies; IgG, immunoglobulin; SD, standard deviation; 95% CI, 95% confidence intervals.Figure 1.David Vega-Morales Grant/research support from: This research was funded as an Investigator Initiated Study by UCB (IIS-2015-104068). The sponsor did not have any role in the design or outcomes of this study., Mario Alberto Garza Elizondo: None declared, Leendert A Trouw: None declared, Karina Itzel González Márquez: None declared, Ernesto Torres-Lopez: None declared, Myriam Eguia Bernal: None declared, SALVADOR AZAHEL LOREDO ALANIS: None declared, Tayde Sarahi Gracia-Arechiga: None declared, Brenda Roxana Vázquez Fuentes: None declared, Diana Daniela Castañeda Martínez: None declared, Martha Mariana Castañeda-Martínez: None declared, Cesar Vidal Solis: None declared, Andres Mendiola-Jimenez: None declared, Mario Cesar Salinas-Carmona: None declared, Pablo Herrera-Sandate: None declared, Alberto Cárdenas: None declared, Gerardo Eugenio Rodriguez-Sanchez: None declared, Dionicio Ángel Galarza-Delgado: None declared