Correlations Among Cartilage Erosion, IgA Level, Red Blood Cell and Platelet Counts in 436 Rheumatoid Arthritis Patients with Path Analysis

There are many factors involve in the cartilage erosion, and the correlations among cartilage erosion, blood IgA level, red blood cells and platelets in rheumatoid arthritis (RA) was explored with path analysis. 436 patients with RA were included. All patients had a complete medical history taken, and basic clinical characteristics, blood biochemical and immunological changes were determined. The cartilage erosions were graded on the X-ray images in hands joints. Statistical analysis was conducted on SAS8.2 package. Multiple linear regression analysis and path analysis was used to seek the correlations among cartilage erosion, blood IgA level and platelets. Results showed that age, disease course, red blood cell (RBC) and platelet (PLT) counts were found to be correlative factors with cartilage erosion in multiple linear regression analysis. In the best-fitting path model from the path analysis, the causal paths relevant to cartilage erosion are the paths from RBC and PLT, and the paths reflecting common anteceding causes includes the paths from IgA to PLT to cartilage erosion, from disease course to IgA to PLT to cartilage erosion, from age to course to IgA to PLT to cartilage erosion. It could be concluded that RBC and PLT are the direct causes for cartilage erosion in RA, and PLT is indirect.