A measure of limited joint motion and deformity correlates with HLA-DRB1 and DQB1 alleles in patients with rheumatoid arthritis

Objective-To assess factors associated with a poor outcome in rheumatoid ar thritis (RA), a measure was developed of limited joint motion and deformity , a deformity index (DI), and correlated biochemical and genetic variables with the magnitude of the DI. Methods-Forty patients were evaluated in a cross sectional study. Clinical measures included the DI and Health Assessment Questionnaire, and disease v ariables included the erythrocyte sedimentation rate, C reactive protein, r heumatoid factor, and HLA-DRB1 and DQB1 alleles. Results-Significant correlations' were noted between increasing DI and dura tion of RA and concentration of C reactive protein. Patients with a DQB1(st ar)301 allele or DR4 allele had a higher DI than those without, and a posit ive trend was noted between increasing DI and dose of DRB1 RA susceptibilit y alleles. The trend was lost when a non-linear regression technique was us ed to remove the effect attributable to C reactive protein, suggesting an i nterrelation between persistent inflammation and genetics in determining to tal joint damage. Conclusions-The DI may be useful to study interactions between genetic and inflammatory processes in rheumatoid disease progression.