Systemic Autoimmune Diseases Unit, Service of Internal Medicine, "Virgen de las Nieves" University Hospital, Granada, Spain

Correspondence to:
Correspondence to:
Dr C Hidalgo-Tenorio
9th floor, Hospital Universitario "Virgen de las Nieves", Avda Fuerzas Armadas No 2, 18014, Granada, Spain; chidalgo72{at}hotmail.com

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.

Keywords: lupus; infections; urinary tract infection; systemic lupus erythematosus

Abbreviations: aCL, anticardiolipin antibodies; ANA, antinuclear antibodies; CI, confidence interval; CL, cutaneous lupus; GEE, generalised estimation equation; LA, lupus anticoagulant; OR, odds ratio; SLE, systemic lupus eythematosus; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index; SLICC/ACR, Systemic Lupus International Collaborating Clinics/American College of Rheumatism; ufc, ??; UTI, urinary tract infection

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