Incidence of clinically diagnosed systemic lupus erythematosus 1992–1998 using the UK General Practice Research Database

PURPOSE: To determine the age- and sex-specific incidence rates of systemic lupus erythematosus (SLE) in the population of the General Practice Research Database (GPRD) between 1.1.1992 and 31.12.1998. METHODS: We searched the GPRD for incident cases of clinically diagnosed SLE with supporting evidence of diagnosis in their medical record. Cases must have had at least 3 years of data in their record prior to date of first diagnosis. We calculated the annual and age- and sex-specific incidence rates of SLE. RESULTS: We identified 390 incident cases of SLE yielding an incidence rate (IR) of 3.02/100 000/year (CI(95) 2.72, 3.32). There were 41 males (IR 0.65/100 000/year (CI(95) 0.45, 0.85)) and 349 females (IR 5.30/100 000/year (CI(95) 4.75, 5.86)). The median age at diagnosis for males and females was 54 and 46 years, respectively, and the peak incidence rates were amongst women aged 30-69 years. The incidence rate ratio for females to males was 8.15 (CI(95) 5.9, 11.6). CONCLUSIONS: This is the first UK-wide study of the incidence of SLE. The results of this study are consistent with previous smaller studies conducted in Nottingham and Birmingham. Although recording of symptoms of SLE is not complete in the GPRD, we conclude that incident cases can be successfully identified because generally there is supporting evidence of diagnosis in medical record.