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Abstract
Objective Lupus nephritis (LN) primarily affects young women, but cases with onset in childhood and advanced age have been reported. The aim of the study is to establish differences in long-term kidney survival among NL onset in childbearing age, in adults, and in older patients.
Methods We included 260 patients, categorized by the age of LN diagnosis (≤18, >18and<45, ≥45 years). Demographic, clinical, histological and therapeutic data were collected at LN diagnosis. At last observation, we estimated the survival free from chronic kidney disease (CKD: eGFR<60 ml/min using CKD-EPI/Schwartz) in the three groups using Kaplan-Meier curves, and differences were assessed with the Log-RANK test. Predictors of CKD among the baseline characteristics were analyzed using the Cox proportional hazard model in univariable and multivariable analysis.
Results The diagnosis of LN was performed in patients <18 years old in 44 cases (16.9%), between 18 and 44 years in 174 (66.9%) and over 45 years in 42 (16.2%). 88% of patients were females, the median serum creatinine of the whole group was 0.9 (0.7–1.3) mg/dl, proteinuria 3.45(2.0- 5.5) g/die, and hypertension was present in 47% of patients. At kidney biopsy 76% had proliferative class (III or IV or mixed). Therapeutic approach did not differ among the age groups, but serum creatinine and chronicity index at kidney biopsy were higher, and eGFR was lower in older patients. In pediatric group, proteinuria was higher and serum complement was lower compared to the other groups. After a median follow-up of 174.5 (80.3- 294.3) months, CKD was diagnosed in 18% of pediatrics, 21% of adults and 33% of elderly (p=0.18). The CKD-free survival was better in the pediatric and adult groups than in older patients (p=0.0059) (figure 1). Age at LN diagnosis predicted CKD at univariable analysis only (OR:1.9218; CI:1.1602–3.1833; p=0.0115). The independent predictors of CKD at multivariable analysis were eGFR (OR:0.9807; CI:0.9700–0.9914, p=0.0005) and chronicity index (OR:1.1988; CI:1.0629–1.352,p=0.0033) (table 1).
Conclusions Kidney survival was worst in elderly LN patients and not different between children and adults. Low eGFR and high chronicity index at kidney biopsy were the independent predictors of CKD.
Predictors of CKD development at last observation among the clinical, histological, and therapeutic features at LN diagnosis. eGFR, estimated glomerular filtration rate; CKD, chronic kidney disease
CKD-free survival in LN patients with different classes of age at LN diagnosis: age <18years, age >18 and <45 years, age ≥45 years. CKD, chronic kidney disease
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