Urinary tract infections and lupus erythematosus.

BACKGROUND Infections are one of the main causes of morbidity and mortality in patients with systemic lupus erythematosus. OBJECTIVE To analyse urinary tract infection (UTI) risk factors in lupus patients; the influence of these factors on disease activity, organ damage, and disease development; the type and prevalence of UTI; and the micro-organisms involved. METHOD 86 control subjects and 81 lupus patients were studied prospectively over a 12 month period and examined on five occasions. Epidemiological data and information on urinary symptoms, disease activity (SLEDAI), and organ damage (SLICC/ACR) data were collected. Autoantibodies, complement levels, urine culture, and antibiogram were determined; urological studies were also carried out. SPPS 10.0 and STATA 6.0. were used for statistical analysis. RESULTS The prevalence of UTI in lupus patients was 36%. Lupus influences the onset of UTI (p = 0.001), regardless of other variables. UTI risk factors in lupus patients were age (p = 0.002), previous cases of UTI (p = 0.0001), antinuclear antibodies (ANA) >1/80 IU/ml (p = 0.022), thrombocytopenia (p = 0.02), and admission to hospital due to UTI (p = 0.002). Leucopenia (p = 0.09) and the weekly administration of methotrexate (p = 0.06) had a bearing on the onset of UTI; disease development (p = 0.99), lupus activity (p = 0.32), and organ damage (p = 0.36) do not. The uropathogen most frequently isolated was E coli (60%). CONCLUSIONS Lupus patients are likely to have UTI, usually manifesting in the lower tract. They are community acquired, basically caused by E coli, and favoured by age, previous UTI, admissions to hospital due to UTI, thrombopenia, ANA, leucopenia, and methotrexate treatments.