A study of immunological profile, disease characteristics and socioeconomic status of a population of rheumatoid arthritis patients in Sri Lanka

Abstract

Objective: To study the immunological profile, disease characteristics and socioeconomic status of a population of patients with rheumatoid arthritis (RA) in Sri Lanka. Methods: A case-control study was undertaken to characterize the immunoglobulin profiles of 105RA and, age and gender matched osteoarthritis (OA) patients (n=30) from the National Hospital, Sri Lanka.Healthy, non-arthritic individuals (n=30) served as controls.Sera were assayed for immunoglobulins [IgG, IgM, IgE and IgA isotypes] by establishing sandwich type ELISA.IgM, IgG and IgA rheumatoid factors (RFs) of 162RA patients were assayed by indirect ELISA. Disease characteristics and socioeconomic factors were accrued via an interviewer-administered questionnaire. Results: Higher IgG, IgM, IgE, IgA and lower IgG1, IgG2 levels were observed in RA sera compared with controls (P<0.05).Novel correlations between disease characteristics and immunoglobulins, as well as group-specific correlation matrices of immunoglobulins and RFs (P<0.05) of seropositive and seronegative patients, were found.Higher IgM-RF and IgA-RF levels in seropositives and IgG-RF in seronegatives were evident compared with controls (P<0.05).Immunoglobulin and RF profiles did not reflect gender disparity of RA (P>0.05).Proportions of seropositives with nodules and erosions were significantly higher than seronegatives (P<0.05).While IgM-RF and erosions positively correlated in the seropositives (P<0.05), the seronegatives showed an inverse correlation between IgG-RF and erosions (P<0.01).Familial clustering imposed a relative risk of 4.7 for developing seropositive RA. Conclusions: This model study provides baseline information on pathogenetic aspects of RA in Sri Lanka, which may have implications for further research on management of the disease.