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

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.

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.

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.

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