Objective, To identify HLA markers for the development of severe disease in psoriatic arthritis (PsA), Methods, Patients with PsA who were followed up prospectively over a 14-year period were included, Clinical and laboratory assessments of both active inflammation and clinical damage were performed at 6-month intervals according to a standard protocol, which also included serologic HLA typing for class I and II antigens, Progression of damage was defined as transition into higher damage states, defined by the number of damaged joints, Both univariate and multivariate models were developed to identify predictors for progression of damage, Results, Univariate analysis revealed that the HLA antigens B27, B39, and DQw3 were associated with disease progression, while HLA-DR7 was ''protective.'' The best multivariate model identified the HLA antigens B27, when DR7 was present, and DQw3, when DR7 was not present, as predicting disease progression across all transitions, while HLA-B39 was associated with progression in early disease, The addition of these HLA indicators to a model containing clinical variables resulted in a significant improvement in fit, Conclusion, The HLA antigens associated with PsA, B27 and B39, are risk factors for disease progression, as is the HLA class II antigen DQw3, In combination with clinical measures of disease, these HLA variables are the dominant predictors of progression.
