Erythrocyte sedimentation rate and C-reactive protein levels are poorly correlated with clinical measures of disease activity in rheumatoid arthritis, systemic lupus erythematosus and osteoarthritis patients.

OBJECTIVE: To determine the patterns and correlation of elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels with outcome measures in rheumatoid arthritis (RA), and compare it to systemic lupus erythematosus (SLE) and osteoarthritis (OA) patients.
METHODS: Brooklyn Outcomes Arthritis Registry Database (BOARD) was analyzed to determine both first visit and mean values of ESR and CRP, along with disease activity measures in each patient. Data were analyzed with descriptive statistics and correlations.
RESULTS: Among all patients half of all (n=377) ESR results were elevated. In RA patients the proportions of having both ESR and CRP elevated, both within normal levels, and only one elevated and the other normal were similar. For all diagnosis, both ESR and CRP have weak positive correlations with disease activity measures measured at first visits. ESR and CRP have a modest positive correlation with each other across all three disease groups.
CONCLUSION: In this cohort of RA, SLE and OA patients, ESR and CRP values were modestly correlated with each other and they were weakly correlated with disease activity measures. These data suggest that another look at the role of ESR and CRP as markers of inflammation in RA patients seen in routine care may be in order.