Background/Purpose:

In the majority of trials on lupus, partial proteinuria recovery (PPR) (≥ 50% decrease in the proteinuria level) is a component of the composite outcome of partial renal remission.

To determine the percentage of patients who achieve complete proteinuria recovery (CPR), PPR and CPR and/or PPR in lupus nephritis (LN) patients receiving standard treatment at 6 months, 1 year and 2 years. The am of this study was to determine if the initial level of proteinuria predicts recovery from proteinuria.

Methods:

We studied all active LN patients registered at the Lupus Clinic (1970-2011).  Proteinuria was defined as >0.5g/24 hours based on a 24 hour urine collection. Patients with proteinuria and at least one of the urinary sediments (hematuria, pyuria or casts) present at the entry of the study 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.

CPR was defined as proteinuria <0.5g/24 hours based on SLEDAI-2K. PPR was a decrease of ≥ 50% in the level of proteinuria from baseline as defined by by SLEDAI-50 responder index (SLEDAI-50-RI).

We determined the percentage of PPR, CPR and PPR and/or CPR achieved: 1) on 1 visit at 6 months, 1 year and 2 years 2) persistent on 2 consecutive visits at 6 months, 1 year and 2 years. The percentage of patients who recovered from proteinuria was evaluated based on initial proteinuria levels with the Kaplan-Meier estimator.

Results:

217 patients (81.8% female) were identified. The age and duration of lupus at the start of the study was 34.2 ± 12.4 and 5.7 ± 6.3 years.

PPR was achieved by 27% of patients at 6 months, 48.3% at 1 year and 69.4% at 2 years. PPR and/ or CPR was achieved by 31.8% of patients at 6 months, 57.6% at 1 year and 79.3% at 2 years. CPR was achieved by 8.8% of patients at 6 months, 35.2% at 1 year and 60.2% at 2 years (table 1). The percentage of PPR, CPR and PPR and/or CPR decreased when proteinuria recovery was required on 2 consecutive visits (Table 1) (Figure 1).

Based on the level of proteinuria, in group 1, 2 and 3 more patients achieved at least PPR compared to CPR at 6 months (p=0.81), 1 and 2 years (p<0.05).

Conclusion:

The identification of partial proteinuria recovery allowed the detection of additional patients who improved their proteinuria on standard of care treatment. 58% of patients achieved at least partial while only 35% achieved CPR at year 1. PPR can serve as an important primary endpoint in research studies and trials.

Table 1. Percentage of PPR, CPR, and PPR or CPR using 1 visit or 2 visits what does this mean 

Figure 1. Comparing Complete, Partial, Partial and/or Complete – All Patients – 1 Visit Definition