Mortality of IgA nephropathy patients: a single center experience over 30 years

Abstract

Research on the prognosis of IgA nephropathy (IgAN) has focused on renal survival, with little information being available on patient survival. Hence, this investigation aimed to explore long-term patient outcome in IgAN patients. Clinical and pathological characteristics at the time of renal biopsy were reviewed in 1,364 IgAN patients from 1979 to 2008. The outcomes were patient death and end stage renal disease (ESRD) progression. Overall, 71 deaths (5.3%) and 277 cases of ESRD (20.6%) occurred during 13,916 person-years. Ten-, 20-, and 30-year patient survival rates were 96.3%, 91.8%, and 82.7%, respectively. More than 50% patient deaths occurred without ESRD progression. Overall mortality was elevated by 43% from an age/sex-matched general population (GP) (standardized mortality ratio [SMR], 1.43; 95% confidence interval [CI], 1.04-1.92). Men had comparable mortality to GP (SMR, 1.22; 95% CI, 0.82-1.75), but, in women, the mortality rate was double (SMR, 2.17; 95% CI, 1.21-3.57). Patients with renal risk factors such as initial renal dysfunction (estimated glomerular filgration rate <60 ml/min per 1.73 m(2); SMR, 1.70; 95% CI, 1.13-2.46), systolic blood pressure ≥ 140 mmHg (SMR, 1.88; 95% CI, 1.19-2.82) or proteinuria ≥ 1 g/day (SMR, 1.66; 95% CI, 1.16-2.29) had an elevated mortality rate. Patients with preserved renal function, normotension, and proteinuria <1 g/day, however, had a similar mortality rate to GP. When risk stratification was performed by counting the number of major risk factors present at diagnosis, low-risk IgAN patients had a mortality rate equal to that of GP, whereas high-risk patients had a mortality rate higher than that of GP. This investigation demonstrated that overall mortality in IgAN patients was higher than that of GP. Women and patients with renal risk factors had a higher mortality than that of GP, Therefore, strategies optimized to alleviate major renal risk factors are warranted to reduce patient mortality.

Figure 1. Cumulative renal and patient survival after renal biopsy.

The primary endpoint was renal (A) and patient survival (B) and composite outcome (C). The numbers of patients remaining at 60, 120, 180, 240, 300, and 360 months of follow-up are shown at the bottom. ESRD, end stage renal disease.

Figure 2. Cumulative renal

(A) and patient survival (B) according to the risk stratification. The primary outcome is patient survival. The numbers of patients remaining at 60, 120, 180, 240, 300, and 360 months of follow-up are shown at the bottom.

Figure 3. Cumulative patient survival after ESRD progression according to the all ESRD patients

(A) and excluding transplantation recipients (B). The primary outcome is patient survival. The numbers of patients remaining at 60, 120, 180, 240, 300, and 360 months of follow-up are shown at the bottom. ESRD, end stage renal disease.

Figure 4. Standardized mortality ratio

(SMR) according to risk stratification. The x-axis represents SMR with 95% confidence interval in log scale. The y-axis represents overall and gender subgroup of IgAN patients.