HLA-DRB1 typing in rheumatoid arthritis: predicting response to specific treatments

Objective-To determine the predictive value of shared epitope alleles for response to treatment in patients with rheumatoid arthritis. Methods-Patients from our previously published triple DIMARD study were tested for the presence of shared epitope alleles (DRB1 star 0401,0404/0408, 0405,0101, 1001,and 1402). Patients who were shared epitope positive were then compared with those who were negative to see if there was a differential effect on therapeutic response. Results-Shared epitope positive patients were much more likely to achieve a 50% response if treated with methotrexate-sulphasalazine-hydroxychloroquine compared with methotrexate alone (94% responders versus 32%, p<0.0001). In contrast shared epitope negative patients did equally well regardless of treatment (88% responders for methotrexate-sulphasalazine-hydroxychloroquine versus 83% for methotrexate). Additionally, a trend toward an inverse relation of the gene dose was seen for response to methotrexate treatment (p=0.05). Conclusions-These data suggest that determining shared epitope status may provide clinical information useful in selecting among treatment options.