[Influence of non-complicated urinary tract infection on renal relapses in proliferative lupus nephritis].

Objective: In patients with proliferative lupus nephritis treated with IV cyclophosphamide, analyze urinary tract infection (UTI) as a cause of treatment delay and renal relapses, compared with lupus nephritis patients without infection.

Patients And Methods: We studied SLE patients (ACR criteria) with renal biopsy showing nephritis class IV. All patients received monthly intravenous cyclophosphamide (CYC) treatment during 6 months. Thereafter patients were assigned to 2 groups: patients who developed UTI, and those who did not; renal function tests, UTI and renal relapses were bimonthly evaluated during one year (follow-up period). To analyze data, t student test, χ(2), Fisher exact (when appropiate), and bivariate analysis, were performed.

Results: We studied 50 patients, 25 with UTI (Group I) and 25 without UTI (G-II).The mean age was 30.07 ± 8.15 years, 82% were female. E. coli was the pathogen most frequently isolated (73%). UTI (G-I) was the cause for treatment delay in 19 cases (76%), compared with 3 patients (12%) in G-II whose treatment was delayed because of some other causes (severe leucopenya, hypersensibility and gastrointestinal side effects) (OR 23.22, 95% CI, 5.26-105.1; P=001). During the follow up, 90.9% of patients in G-I reached partial or complete renal remission within 3 months, but only 35% mantained remission after the year of follow up. Meanwhile, patients in G-II had complet and partial renal remission of 85% and 63%, respectively. In the first group we observed persistent albuminuria (P<05), low complement levels and high ab-dsDNA titers. Renal flares were present in 18 patients in G-I and 9 in G-II.

Conclusions: UTI in lupus nephritis patients has a negative impact. It leads to delayed CYC therapy and to a higher renal flare rate.