Comparison of (a) C-reactive protein (CRP) levels, (b) rheumatoid factor (RF) IgM titers, and (c) RF IgA titers in patients below (CD19low) and above (CD19high) the mean of the study population (110 B cells/ml), which was determined after a mean disease of 4.4 years. The different time points of observation are indicated on the x axis, starting from the first visit in the rheumatology clinic. All graphs depict the mean and standard error of the mean. *P < 0.05, **P < 0.01, ***P < 0.001.
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