Method of assessing rheumatoid arthritis by measuring anti-CCP and anti-PIK3CD

A method for assessing a severity of rheumatoid arthritis (RA) in vitro by biochemical markers, comprising

• a) measuring in a whole blood, plasma or serum sample the concentration of at least anti-cyclic citrullinated peptides (anti-CCP) and anti-PIK3CD;
• b) combining the concentration values measured for anti-CCP and anti-PIK3CD in (a);
• and
• c) correlating from an combined value from (b) to the severity of RA, wherein the higher the combined value compared to the cut-off combined concentration value measured for anti-CCP and anti-PIK3CD from a reference population is indicative for the severity of RA in the patient.

A method for differentiation of rheumatoid arthritis (RA) from osteoarthritis (OA) in vitro by biochemical markers, comprising

• a) measuring in a whole blood, plasma or serum sample the concentration of at least anti-cyclic citrullinated peptides (anti-CCP) and anti-PIK3CD;
• b) combining the concentration values measured for anti-CCP and anti-PIK3CD in (a);
• and
• c) differentiating from an increased combined value from (b) RA from OA, wherein an increased combined value compared to the cut-off combined concentration value measured for anti-CCP and anti-PIK3CD from a reference population is indicative for the presence of RA.