Antibodies of IgG, IgA and IgM isotypes against cyclic citrullinated peptide precede the development of rheumatoid arthritis

Table 3 Sensitivity and specificity for various anti-CCP2 antibody isotypes for 71 pre-patients, 274 matched controls and 60 patients

Anti-CCP antibody	Sensitivity	Sensitivity	Specificity
	pre-patients	patients
IgG^P	33.8***	71.7***	98.9
IgA^P	23.9***	43.3***	97.1
IgM^aP	11.8	32.8***	93.9
IgG^E	32.4***	71.2***	98.5

The cut-off values for positivity for the antibodies were calculated using ROC curves
^aAnalysis of IgM in pre-patients; n = 68, in patients; n = 58, and controls; n = 263, ^E analysed with a kit from Euro-Diagnostica, ^P analysed with a kit from Phadia.***P < 0.001. Anti-CCP, anti-cyclic citrullinated peptide; ROC, receiver operating characteristic; Ig, immunoglobulin.

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