Long-term follow-up of patients with anti-cyclic citrullinated peptide antibody-positive connective tissue disease: a retrospective observational study including information on the HLA-DRB1 allele and citrullination dependency

Table 2 Comparison of characteristics between anti-CCP-positive non-RA CTD patients and RA-overlapping CTD patients

	Non-RA n = 31	RA-overlapping n = 41	p value	OR^# (95% CI)
Age, median (IQR), years	59.0 (41.5–68.0)	64.0 (52.0–69.0)	0.30	ND
Women, %	87.1	92.7	0.45	1.86 (0.29–13.7)
Duration of CTD, median (IQR), years	10.0 (6.0–16.0)	14.0 (8.0–21.5)	0.25	ND
Arthritis	18 (58%)	41 (100%)	2.9 × 10⁻⁶	Inf (5.9 Inf)
Bone erosion	0/25 (0%)	29/41 (70.7%)	1.4 × 10⁻⁹	Inf (12.9 Inf)
RF(+ve/−ve)	18/10 (64%)	40/1 (98%)	3.1 × 10⁻⁴	21.2 (2.7–982)
Titer of aCCP^†, median (IQR), U/mL	29.4 (7.9–100)	72.6 (32.2–100)	0.045	ND
Negative conversion of aCCP	6/28 (21.4%)	5/36 (13.9%)	0.51	0.60 (0.13–2.7)
Usage of DMARDs	18 (58.1%)	37 (90.2%)	2.0 × 10⁻³	6.49 (1.69–31.3)
Usage of a medium dose of glucocorticoids^‡	21 (67.7%)	18 (43.9%)	0.06	0.38 (0.12–1.09)
HLA-DRB1 SE^§	6/22 (27.2%)	20/32 (62.5%)	0.014	4.3 (1.20–17.5)

CTD connective tissue disease, OR odds ratio, 95% CI 95% confidence interval, ND no data, Inf infinite, SD standard deviation, RF rheumatoid factor, aCCP anti-CCP antibody, DMARDs disease-modifying antirheumatic drugs, including methotrexate, bucillamine, salazosulfapyridine, tacrolimus, cyclosporine, mizoribine, etanercept, and tocilizumab, SE shared epitope
^#Calculated for categorical variables
^†≥ 100 U/mL was calculated as 100 U/mL
^‡≥ 15 mg/day of a prednisolone equivalent
^§Assessed in 22 out of 31 patients in the non-RA group and 32 out of 41 patients in the RA-overlapping group

ISSN: 1478-6362