PTPN22polymorphism and anti-cyclic citrullinated peptide antibodies in combination strongly predicts future onset of rheumatoid arthritis and has a specificity of 100% for the disease

Table 3 Conditional logistic regression analyses of combinations of genes and antibodies

Combination of variables	Pre-patients		Controls		OR	95% CI
	n	%	n	%
PTPN22 CT+TT^- + anti-CCP Abs^-	39	45.3	272	78.4	1.00
PTPN22 CT+TT⁺ + anti-CCP Abs^-	15	17.5	70	20.2	1.20	0.62–2.35
PTPN22 CT+TT^- + anti-CCP Abs⁺	13	15.1	5	1.4	16.61	4.68–58.97
PTPN22 CT+TT⁺ + anti-CCP Abs⁺	19	22.1	0^a	0.0	132.03^a	17.84–2720.91^a
PTPN22 CT+TT^- + IgG-RF^-	27	48.2	175	76.1	1.00
PTPN22 CT+TT⁺ + IgG-RF^-	19	33.9	46	20.0	2.47	1.26–4.85
PTPN22 CT+TT^- + IgG-RF⁺	9	16.1	6	2.6	10.08	3.00–33.94
PTPN22 CT+TT⁺ + IgG-RF⁺	1	1.8	3	1.3	1.50	0.15–14.84
PTPN22 CT+TT^- + IgA-RF^-	23	41.1	171	74.3	1.00
PTPN22 CT+TT⁺ + IgA-RF^-	11	19.6	47	20.4	1.55	0.69–3.49
PTPN22 CT+TT^- + IgA-RF⁺	13	23.2	10	4.4	9.23	3.31–25.76
PTPN22 CT+TT⁺ + IgA-RF⁺	9	16.1	2	0.9	21.42	4.45–103.16
PTPN22 CT+TT^- + IgM-RF^-	28	50.0	170	73.9	1.00
PTPN22 CT+TT⁺ + IgM-RF^-	16	28.6	46	20.0	1.97	0.98–4.04
PTPN22 CT+TT^- + IgM-RF⁺	8	14.3	11	4.8	4.65	1.65–13.13
PTPN22 CT+TT⁺ + IgM-RF⁺	4	7.1	3	1.3	10.70	1.78–64.23
PTPN22 CT+TT^- + SE^-	24	27.6	86	50.6	1.00
PTPN22 CT+TT⁺ + SE^-	14	16.1	18	10.6	3.35	1.34–8.26
PTPN22 CT+TT^- + SE⁺	28	32.2	54	31.8	2.12	1.06–4.25
PTPN22 CT+TT⁺ + SE⁺	21	24.1	12	7.0	7.85	3.03–20.30

Results of conditional logistic regression analyses of carriage of the PTPN22 1858T variant (CT + TT), HLA shared epitope (SE), anti-cyclic citrullinated peptide antibodies (anti-CCP Abs) or rheumatoid factors (RFs) of IgG, IgM, or IgA isotype for the prediction of rheumatoid arthritis in individuals who later developed the disease and matched controls. ^aCalculations made with a hypothetical control individual positive for both the PTPN22 1858T variant and anti-CCP antibodies.

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