Background New Classifications of HLADRB1 alleles expanding the concept of the Shared Epitope (SE) hypothesis have allowed to profile predisposing or protective determinants of aggressive disease course in Caucasian patients with Rheumatoid Arthritis (RA). In mestizo Latin American (LA) subjects there is scarce information available.

Objectives To determine if SE subtypes according to Gao classification are associated with risk of more severe joint damage in a RA LA cohort

Methods A cross sectional study was conducted in RA outpatients between September to December 2013. HLA–DRB1 typification was performed by a polymerase chain reaction–based method, using a panel of sequence-specific oligonucleotides. DRB1 subtyping was described according to the classification of HLA DRB1 alleles by Gao et al: E₁, E₃ (QRRAA), E₂/E_x (KRAA), E_x (ERAA) or Ex (DERAA). Then four categories were pre determined: I = none present (0/0); II = E₁,E₃ (+/0 or +/+), III = E₁, E₃, E_x(+/+), and IV= E_x (+/0 or +/+). A single blind investigator (RG) determined Joint Damage according to erosion, narrowing and total Sharp Van Der Heijde (Sharp VDH) score. Other severity risk factors were measured. A univariable Student's t test to compare all categories was done. Then a regression multivariable linear analysis was performed to determine the association of these DRB1 categories with joint damage adjusted to other risk factors. All analyses were performed using SPSS 21.0.

Results One hundred and seventy nine patients were included, 90.5% (162) were women, media of age was 58.9 (12.87) years, Disease duration 15.84 (11.76) years and 31 patients (17.3%) had tobacco habits in the past. The total, erosion and narrowing space Sharp VDH score were 110.33 (86.36), 41.85 (48.45) and 68.48 (41.26) respectively, DAS28 was 4.69 (1.26), MDHAQ was 0.88 (0.60) and Charlson index 0.65 (1.27). On univariate analysis Category II was associated to Sharp VDH score (Table 1)

After the multivariable analyses (adjusted for age, disease duration, gender, tobacco, Rheumatoid Factor, DAS28 and Charlson comorbidity index) category II persisted associated with erosions (B: 29.32; IC 95%: 1.19-57.44, p=0.041), and total (B: 50.52; IC 95%: 2.59-98.45, p=0.039) Sharp VDH index but not with narrowing score (B: 21.20; IC 95%: -1.02-43.42, p=0.061)

Conclusions Presence of HDRB1 E₁ and/or E₃ alleles are independently associated with structural severity on our RA Peruvian patients.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.5660