Background The level of proteinuria is an important measure to document improvement in lupus nephritis. The recovery time from abnormal levels of proteinuria has not been well described with standard treatment.
Objectives To determine: 1) the recovery time from proteinuria in lupus nephritis patients receiving standard treatment and 2) whether the initial level of proteinuria predicts the percentage of patients who improve and the time to improvement.
Methods We studied all lupus nephritis patients registered at the Lupus Clinic; 1970-2011. Proteinuria was defined as ≥0.5g/24 hours as defined by SLEDAI-2K.
Patients with proteinuria and at least one of the urinary sediments (hematuria, pyuria or casts) present at initial visit and persistent on 2 consecutive visits were enrolled. Patients were grouped into: group 1 as 0.5-0.9g/day, group 2 as 1-2g/day and group 3 as ≥2g/day. Recovery from proteinuria was defined as proteinuria <0.5g/24 hours. We determined the time to recovery from proteinuria in all patients and in each of the 3 groups separately with the Kaplan-Meier estimator.
Results 244 patients (F 95%) were identified. 59% were Caucasian, 16% Black, 14% Asian, and 11% other. Age at diagnosis of lupus was 28.0±12.4 years, age and duration of lupus at start of study was 34.0±12.2 and 6.0±6.5 years, respectively. The mean length of follow-up period was 2.3±2.7 years. SLEDAI-2K was 16.9±6.8 at the start and 7.9±7.2 at the end of the study.
53% of the patients recovered from proteinuria within 2 years while 74% recovered within 5 years (Figure 1). The level of proteinuria at baseline visit predicted the time to improvement and the percentage of patients who improved. Patients with a higher level of proteinuria at baseline needed a longer time to normalize their proteinuria [group 1 (n=21/29): 1.2±0.7 years, group 2 (n=44/74): 1.63±1.79 years and group 3 (n=66/111): 2.83±2.86 years (p=0.004)] (Figure 1).
Conclusions Almost 50% of the lupus nephritis patients normalize their proteinuria by year 2 and others continue to improve over time; 74% recovered by year 5. The level of proteinuria at baseline visit predicts the percent of patients who respond over time and the time to improvement.
Disclosure of Interest None Declared