Performance of serum adenosine deaminase in measuring disease activity in rheumatoid arthritis patients

Numerous tools to assess activity of rheumatoid arthritis (RA) are available to use. For any marker to be a more appropriate indicator of disease activity, it should be more authentic to the patho-physiologic basis of the disease. To determine the performance of serum adenosine deaminase (sADA) in measuring disease activity in RA. 100 RA patients and 100 matched controls were included in the study. The disease activity score (DAS28) with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were assessed. sADA level was determined by spectrophotometry. The sADA level was integrated in the DAS28 formulae and the corresponding values were determined. The mean age of the RA patients was 61.8 ± 9.7 years, 68% were females and they had a disease duration of 12.5 ± 3.7 years. The mean DAS28-ESR was 4.2 ± 1.3 and DAS28-CRP 3.5 ± 1.1. The mean sADA was significantly higher in the patients (33.6 ± 11.6 U/L) compared to the control (25.1 ± 9.9 U/L) (p < 0.001). The sADA level and DAS28-sADA did not differ according to the gender, methotrexate use, rheumatoid factor or anti-citrullinated protein autoantibodies positivity. The mean DAS28-sADA significantly increased in higher activity categories (p < 0.001). sADA significantly correlated with the disease activity parameters. DAS28-sADA significantly correlated with DAS28-ESR (r = 0.57, p < 0.001) and DAS28-CRP (r = 0.604, p < 0.001). DAS28-sADA showed a sensitivity of 0.9 and specificity 0.69 for detection of disease activity measured with DAS28-ESR and was 0.88 and 0.65 when measured with DAS28-CRP. Integration of sADA in the DAS28 index can be a useful marker that reflects RA activity.