Ten-Year Follow-up of Patients with Epidemic Post Infectious Glomerulonephritis

Abstract

Background: Scarce information on outcomes of epidemic post infectious glomerulonephritis is available. This is a 10-year follow-up of the patients that developed acute glomerulonephritis in an epidemic outbreak caused by group C Streptococcus zooepidemicus in Brazil in 1998, that were also previously evaluated 2 and 5 years after the acute episode.

Methods: In this prospective study 60 cases (out of 134 in 1998) were reevaluated after 10 years, as well as community controls matched by gender and age. They underwent clinical and renal function evaluation, including serum creatinine and cystatin C, estimated glomerular filtration rate (eGFR), albuminuria and hematuria.

Results: Comparisons of clinical and renal function aspects of 60 patients and 48 community controls have not shown significant differences (eGFR <60 ml/min/1.73 m2 and/or albuminuria >30 mg/g creatinine: 13.8% vs. 12.2%, respectively, p = 0.817) except for a higher frequency of hypertension in the cases (45.0% vs. 20.8%, p = 0.009). Comparing the same patients affected in the acute episode, 2, 5 and 10 years later, it was observed an improvement of median eGFR levels at 2 years and a trend toward subsequent stabilization in these levels, associated with decrease in albuminuria and increased hypertension rates in the last survey. At 10 years it was not observed additional reduction of renal function using serum creatinine, eGFR and cystatin C.

Conclusions: During the acute episode of epidemic GN a considerable proportion of patients presented hypertension and reduced renal function; after 2 years and particularly at this 10-year follow-up survey there was no worsening of renal function parameters, except for persistent higher frequency of hypertension. Nevertheless, a longer follow up is necessary to confirm that progressive loss of renal function will not occur.

Fig 1. Comparison of the estimated GFR-creatinine values in the cases measured during the follow-up.

Values are eGFR-creatinine (mL/min/1.73m²) expressed as median (interquartile range (IQR). The overall comparison between groups using the Friedman’s test was significant (p <0.001) and the multiple comparison tests (Wilcoxon’s test with Bonferroni’s correction (p level of significance: <0.020) yielded the following results for the pairwise comparisons: baseline vs. 2 yrs: p<0.001, baseline vs. 5 yrs: p = 0.005, baseline vs. 10 yrs: p<0.001; 2 yrs vs. 5 yrs: p = 0.835, 2 yrs vs. 10 yrs: 0.008; 5 yrs vs. 10 yrs: p<0.001.