Rheumatoid Arthritis (RA) disease activity plays an important role in patients disability. A standardized approach to measure it was achieved by using disease activity score (DAS) based on erythrocyte sedimentation rate (ESR) and more recently C-reactive protein (CRP). In this study we will assess the role and influence of ESR and CRP in evaluating and assessing the disease activity.
This is a retrospective, longitudinal study, whose data was obtained from the national RA patient clinical database BioreportAR (following ACR criteria) under biological disease modifying anti-rheumatic drugs (BDMARDs), involving 71 patients from CHLO-Hospital Egas Moniz. The ESR and CRP of each patient were recorded from 2 separated visits. The swollen joint counts (SJC), tender joint counts (TJC), visual analog scale (VAS) for pain, patient global assessment and physician global assessment were also recorded. DAS 28-ESR, DAS 28-CRP, simplified disease activity index (SDAI) and clinical disease activity index (CDAI) were calculated. The relevant Pearson correlations were established between variables.
A sample of 71 patients with an average age of 55 years old and an average RA duration of 9,8 years, was analysed. ESR and CRP correlated poorly between themselves (r=0,31, p<0,001) and they were shown not to be significant predictors of SJC (ESR r=0,29 p< 0,001 and CRP r=0,089 p<0,001) or TJC (ESR r=0,28 p<0,001 and CRP r=0,072 p<0,001). However DAS-ESR and DAS-CRP were highly correlated (r=0,88, p<0,001) as also as, DAS ESR-CDAI (r=0,89, p<0,001), DAS RCP-CDAI (r= 0,88 p< 0,001) and SDAI-CDAI (r=0,89 p<0,001). DAS-CRP values were lower than those in DAS-ESR, but in 84,7% of the visits disease activity status were.
The significant correlation between DAS-ESR and DAS-CRP, indicated that it will not be necessary to perform both evaluations. DAS-CRP yielded a better activity score more often than DAS-ESR, but with 84,7% of concordance in the disease activity status, indicating that both measures are useful for assessing disease activity in RA. Furthermore the correlation between DAS scores and CDAI, and also between SDAI-CDAI may enable physicians to easily assess the disease activity without ESR or CRP values.