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.