CLINICAL-FEATURES AND RACE-SPECIFIC INCIDENCE PREVALENCE RATES OF SYSTEMIC LUPUS-ERYTHEMATOSUS IN A GEOGRAPHICALLY COMPLETE COHORT OF PATIENTS/

Objectives-To assess race-specific incidence and prevalence rates for systemic lupus erythematosus (SLE) using 1991 National Census data and to ascertain the frequency of clinical/laboratory features of a geogr aphically complete cohort of patients with SLE. Methods-Multiple metho ds of retrieval were used to ascertain SLE patients including screenin g request cards for immunology investigations. Patients were classifie d according to the revised ARA criteria. Multiple logistic regression analysis was used to study the effects of age at diagnosis on the freq uency of clinical/laboratory SLE features. Results-The overall one yea r period prevalence rate for SLE was 24.7 (age adjusted, 95% CI: 20.7- 28.8)/100 000. Highest rates were seen in Afro-Caribbeans (207 (111-30 2)/100 000), followed by Asians (48.8 (10.5-87.1)/100 000), and then W hites (20.3 (16.6-24.0)/100 000). The mean age at diagnosis of SLE was 40.9 years (range: 11-83) with a mean interval between first definite SLE symptom and diagnosis of 61 months (0-518). In 85% of patients th e first definite lupus feature was musculoskeletal and/or cutaneous. I n this SLE cohort renal disease (22%) was observed less commonly than in previous studies and the 'classic' butterfly rash was present in on ly 30% of patients. Malar rash, thrombocytopaenia, positive anti-dsDNA antibodies, hypocomplementaemia (C4), and positive IgG anticardiolipi n antibodies were all seen less commonly with increasing age at diagno sis. Conclusions-A closer estimate of the true frequency of clinical/l aboratory SLE manifestations is likely from this geographically comple te cohort of patients compared with studies that may be skewed by refe rral patterns.