Predictive role of serum rheumatoid factor in different disease pattern of psoriasis and psoriatic arthritis

Abstract
Background
Psoriasis is a multisystem inflammatory disorder with variable morphology, clinical pattern and multiple comorbidities. Interplay between genetic and environmental factors leading to an aberrant immune response in the skin may contribute to disease development. The assessment for risk factors, signs, and symptoms of potential comorbid diseases is an important component of patient management. The aim of this study is to determine rheumatoid factors (RF) positivity and its levels in psoriasis patients, and describe its relationship with the demographic and clinical characteristics, comorbidities, and disease patterns of psoriasis.

Results
Rheumatoid factor was positive in psoriatic patients more than control,30% of patients had positive rheumatoid factor while only 10% of control had positive results. Rheumatoid factor level was 63.8 ± 186.7 IU/ml in psoriasis vs. 9.3 ± 12.3 in control. Thirty percent of psoriasis patients have positive rheumatoid factor vs. 10% of control. There was no significant statistical difference between psoriasis patients with or without arthritis as regard rheumatoid factor positivity and titer; rheumatoid factor was positive in 20% in psoriatic patients with arthritis vs. 26% in psoriatic patients without arthritis. In psoriatic patients, the status of rheumatoid factor did not relate to disease severity, onset, course, site of affection, presence of scalp, nail affection, and presence of dactylitis (p value>0.5).

Conclusion
Psoriasis was associated with higher seropositivity of RF compared to age-matched non-psoriatic healthy controls. Occurrence and level of rheumatoid factor were not associated with severity or clinical pattern of psoriasis.