Background/Purpose:

The identification of partial proteinuria recovery (PPR) of  ≥ 50% allows for the detection of an additional number of patients who improve their proteinuria on standard of care treatment.  The long term outcome of patients with  ≥ 50% PPR at 1 year is not well studied.

To determine the prognostic value of PPR and complete proteinuria recovery (CPR) at 1 year on long term outcomes compared to patients who did not recover proteinuria  ≥ 50% on standard of care therapy.

Methods:

All active lupus nephritis (LN) patients registered at a large lupus clinic from 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 entry into the study and persistent on 2 consecutive visits were enrolled.

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 SLEDAI-2K responder index-50 (SLEDAI-50-RI). Not recovered was defined as less than 50% recovery.  Proteinuria recovery was identified if present on 2 consecutive visits within 1 year.

The long term outcomes (death, eGFR<15, dialysis or kidney transplant, SLICC Damage Index (SDI)>0, SDI>3) occurring after the identification of proteinuria related to LN at entry into the study were studied. The mean time to long term outcome was determined

Proportional hazard models were used to determine the hazard ratio (HR) for long term outcomes for the different recovery definitions.

Results:

217 patients (81.8% female) were identified. At 1 year: 45 patients achieved PPR, 48 CPR and 124 not recovered.

Long term outcomes: eGFR< 15 was identified in 14.3% of the patients, dialysis or kidney transplant in 12.8%, .18% of the patient died and 56% developed damage (SDI>0) with 30.7% with SDI >3.

The mean time to event from 1^st visit in the study were:  7.0 ± 8.3 years for death (n=39),  3.7 ± 3.7 years for eGFR< 15 (n=30), 5.5 ± 6.0 for dialysis or kidney transplant (n=20), 3.6 ± 5.6 years for SDI>0 (n=75) and 6.1 ± 7.3 years for SDI>3 (n=57).

Achieving a PPR at 1 year protects from the development of eGFR<15; HR=0.29. Achieving a CPR at 1 year protects from the development of eGFR<15 (HR=0.25), accrual of damage with SDI>3 (HR=0.23) and none with CPR at 1 year subsequently went on to dialysis or transplant. (Table 1).

Conclusion:

Achieving complete recovery from proteinuria in patients with active lupus nephritis at 1 year from the onset of lupus nephritis protects against comorbidities including end stage kidney disease, dialysis and transplant, organ damage and death. Nonetheless, achieving at least partial recovery in proteinuria, ≥ 50%, at year 1 from the onset of lupus nephritis protects against the development of  eGFR<15.

Table 1. Time to development of event in patient who achieved CPR and PPR at 1 year compared to patients without proteinuria recovery