Familial Tendency of Rheumatoid Arthritis among Patients Attending Specialist Clinics in Sri Lanka

Abstract

Rheumatoid arthritis (RA) is an auto immune disease mainly caused by a combination of genetic and environmental factors. Few studies on familial incidence for RA have been conducted in Sri Lanka. The aims were to document patients with RA who have one or more family members affected with RA, describe special clinical features associated RA and determine the patterns of inheritance of familial RA. A descriptive and cross sectional study with 100 consecutive patients with confirmed diagnosis of RA attending specialist Rheumatology clinics were recruited. Data were collected using an interview administered questionnaire, relevant physical examination and testing for Rheumatoid Factor (RF). A complete three generation pedigree was complied for participants with positive family history. The data were entered and validated in a SPSS data base and some data was analysed using descriptive statistics. The statistical significance difference was analyzed using chisquare test. The vast majority of participants (92%) were females. Only 23% had positive family history. In 46%, the onset was before the age of 40 years and 16 out of 23 with positive family history manifested before 40 years. Forty one percent (41%) of the participants had positive RF, in which 10% (10/23) were in the familial group. The commonest clinical feature was arthritis of 3 or more joints (80%) and commonly involved joints were hands and wrists. Soft tissues surrounding the joints (35%) which were most common non articular manifestation, in which 9% was in the familial group. Out of patients with family history 17 had an autosomal dominant (AD) pattern of inheritance while 6 had AD pattern with reduced penetrance. The sporadic form of the disease was more common among study population. The age of onset of the disease was earlier among patients with positive family history. RF, clinical features, joint involvement and non- articular manifestation did not have any marked difference depending on the family history. AD pattern of inheritance was more common.