[Clinical and laboratory characteristics of rheumatoid arthritis with positive antinuclear antibody]

To analyse the clinical and laboratory characteristics of antinuclear antibody (ANA) positive rheumatoid arthritis (RA) patients.

The clinical and laboratory data of 428 RA cases from Department of of Rheumatology and Immunology Peking University Third Hospital from Jan 2013 to Dec 2018 were collected and used to analyse characters between ANA positive group and ANA negative group. T test was used for the quantitative data in accordance with normal distribution. Wilcoxon rank sum test was used for the quantitative data of non normal distribution. The qualitative data were analyzed by chi square test. But while 1≤theoretical frequency < 5, chi square test of corrected four grid table was used. And Fisher exact probability method was used when theoretical frequency < 1.

The number of ANA positive group was 231 (54%). The female rate was obviously higher in ANA positive group (82.7% vs. 63.5%, χ²=20.355, P < 0.01). The rate of metatarsophalangeal joints (MTPJs) involvement was lower in ANA positive group (22.1%) than in ANA negative group (33.0) (χ²=6.414, P < 0.05). The incidence of secondary Sjögren's syndrome (sSS) was much higher in ANA positive group(19.5% vs. 4.1%, χ²=23.300, P < 0.01). The positivity of rheumatoid factor (RF), as well as the positivity of anti-cyclic citrullinated peptide(CCP) antibody was much higher in ANA positive group (77.1% vs. 53.8%, χ²=25.743, P < 0.01, 74.9% vs. 59.4%, χ²=11.694, P < 0.01, respectively). The levels of immunoglobulin G (IgG) and immunoglobulin M (IgM) of ANA positive group were higher [(15.1±5.1) g/L vs. (13.8±5.3) g/L, t=2.359, P < 0.05, 1.25 (0.92) g/L vs. 1.05 (0.65) g/L, Z=-3.449, P < 0.01, respectively]. But the levels of hemoglobin (Hb) and platelet (PLT) was lower in ANA positive group[(109.64±17.98) vs. (114.47±18.48) g/L, t=-2.734, P < 0.01; (266.4×10⁹±104.6×10⁹) vs. (295.9×10⁹±100.1×10⁹) /L, t=-2.970, P < 0.01, respectively].

The incidence of sSS was obviously higher in ANA positive group than in ANA negative group. Serum IgG of ANA positive group was higher, but Hb and PLT were lower.