[Clinical characteristics of psoriatic arthritis with positive rheumatoid factor or anti-cyclic citrullinated peptide antibody].

OBJECTIVE: To analyze the clinical and laboratory features of psoriatic arthritis (PsA) patients with positive rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP) antibody.

METHODS: In the study, 77 PsA patients who were hospitalized in the Department of Rheumatology and Immunology of Peking University Third Hospital from January 2007 to June 2019 were enrolled. All the patients met Classification Criteria for Psoriatic Arthritis or Moll or Wright Criteria. Rheumatoid factor (RF) and anti-cyclic-citrullinated peptide (CCP) antibody were tested in these patients. According to whether anti-CCP antibody or RF was detected in serum, all the patients were divided into anti-CCP antibody or RF positive group (15 cases), anti-CCP antibody or RF negative group (62 cases). According to the detection of anti-CCP antibody in serum, all the patients were divided into anti-CCP antibody positive group (7 cases) and anti-CCP antibody negative group (70 cases). Clinical and laboratory data were collected. The differences of clinical and laboratory indicators between the RF or anti-CCP antibody positive and negative PsA patients were compared. Clinical and laboratory indicators between the anti-CCP antibody positive and negative patients were also compared.

RESULTS: Among the 77 patients, 15 were RF or anti-CCP antibody positive, of whom 8 were only RF positive and 2 were only anti-CCP antibody positive, and both of RF and anti-CCP antibody were positive in 5 cases. The RF or anti-CCP antibody positive PsA patients were older than those in the negative group [(58.2±14.8) years vs. (46.69±12.27) years, P=0.002]. And metacarpophalangeal joints, elbow joints and shoulder joints were more likely to be involved in RF or anti-CCP antibody positive PsA patients. PsA patients in the anti-CCP antibody positive group were older than those in the negative group [(62.43±14.34) years vs. (47.59±12.75) years old, P=0.005]. The positive rate of RF and serum level of fibrinogen in the anti-CCP antibody positive group were higher than those in the negative group. The PsA patients in the anti-CCP antibody positive group were all polyarthritis, while 68.6% patients in the negative group were polyarthritis, but there was no statistical difference between the two groups. There was no statistical difference in sausage fingers/toes, changes in nails and enthesitis, and bone erosion on radiographs between the RF or anti-CCP antibody positive and negative PsA patients. There was also no statistical difference in sausage fingers/toes, bone erosion on radiographs, and changes in nails and enthesitis between the anti-CCP antibody positive and negative patients.

CONCLUSION: RF and anti-CCP antibodies can be detected in the serum of some PsA patients. RF or anti-CCP antibody positive PsA patients were older than those in negative PsA patients. Metacarpophalangeal joints, elbow joints and shoulder joints were more likely to be involved in RF or anti-CCP antibody positive PsA patients. Anti-CCP antibody positive PsA patients were older and had higher levels of RF positive rate and fibrinogen level.