Prevalence of rheumatoid factor (RF) and anti-native-DNA antibodies (anti-n DNA) in different age subpopulations

In this study, we have evaluated the prevalence of RF and anti-n-DNA in different age subpopulations grouped according to their clinical status. RF and anti-n-DNA were measured in the serum of 51 elderly people considered to be successfully aging (group 1), 65 chronically ill elderly (group 2), 65 chronically ill patients under 65 years (group 3) and 30 patients with rheumatoid arthritis (group 4). The results were compared to 100 healthy persons as a control group under 65 years. The prevalences of RF in group 1, group 2 and group 3 were significantly higher than the healthy younger controls. Particularly the difference between group 2 and the control group was markedly significant (p<0.001). There was not any difference between group 1 and 2. In multiple logistic regression analysis, we found significant relationship between RF positivity and chronic illness and also being elderly (r=0.18, p<0.01 and r=0.14 p<0.05). When being elderly factor was added to the analysis of relationship of RF and chronic illness, it was seen that the relation diminished but persisted (r=0.11, p<0.05). None of the patients in our study groups had antibodies to n-DNA. In conclusion, we suggest that the prevalence of RF rises in both chronic illness and being elderly, but chronic illness is more effective on the RF positivity than being elderly.