Comparison of antinuclear antibody determinations in unselected sera by consumption test and immunofluorescence

The correlation of the determination of antinuclear antibodies, as shown by consumption tests and immunofluorescence was investigated in a collective of 100 sera of patients suspected for SLE, collagenosis and rheumatoid arthritis, sent for routine screening investigation. The results of both methods correlated in 78% of sera, both results being either positive or negative. No correlation was observed in 22% of sera, one test being positive, the other negative. Statistical evaluation by the X2 test showed that both techniques did not differ statistically in their results. A correlation coefficient r=0,45 indicated furthermore that the results of both techniques correlated significantly. The percentage of positive results obtained with these and other methods is discussed.