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Abstract
Background/Purpose Diagnosis of Lupus Nephritis (LN) is currently based on laboratory tests and renal histopathology. The role of histopathological features in determining long term outcomes is unclear. The objectives are to determine if clinical and biochemical parameters at baseline could identify renal histopathological class and to assess the clinico-histopathological predictors of renal response.
Methods This is a single centre retrospective study comprising 334 LN renal biopsies. Clinical and biochemical parameters at the time of biopsy were noted and their association with histopathological class, activity and chronicity scores (AS/CS) (ISN/RPS classification) were evaluated. Complete, partial or no response(CR, PR, NR) for the renal outcome (EULAR/EDTA) at 1 year were calculated for 293 patients. Binary logistic regression was done to look for the predictors of NR.
Results Class III/IV LN was seen in 240(71.8%). Hypertension was seen in (52.1%) of class III/IV and <25% each with class II, V and combined class(p<0.001). Class III/IV had lower eGFR [87.6(62.75–118.8)] (p<0.001) than the other classes. Nephrotic range proteinuria was seen in 32% of class V and 21% in class III/IV (p=0.004) Among class-III/IV AS had weak correlation with baseline UPCR (r=0.31) and eGFR (r=-0.172) (p<0.01). CS had weak negative correlation with eGFR (r=-0.212,p<0.01). NR at 1 year was higher in males (OR-4.6,95%CI-1.9–10.8,p<0.001), those with abnormal serum creatinine (OR-3.3,95%:CI1.6–7.02, p-0.001), higher renal SLEDAI (p<0.05), higher AS, CS (p<0.001), interstitial inflammation and tubular atrophy(p<0.005) (Table-1). On binary logistic regression a combined clinico-histopathological model comprising of serum creatinine, UPCR, male sex and CS performed best in predicting NR (figure 1).
Comparison of baseline characteristics among those who attained any response (CR/PR) versus others at one year
ROC curve and AUC for the three different modelsModel 1: Baseline serum creatinine, urine PCR, male sex; AUC −0.694(0.609–0.779), p <0.001Model 2: Baseline serum creatinine, urine PCR, male sex, chronicity score; AUC −0.740(0.660–0.820), p<0.00lModel 3: Baseline serum creatinine, urine PCR, male sex, chronicitv score, crescents, interstitial inflammation;AUC −0.744(0.664–0.824), p<0.00lAUC, Area Under Curve; ROC, Receiver-Operating Characteristics
Conclusion Clinical and biochemical parameters can predict the renal histological class to a fair extent but have limited value in predicting the activity and chronicity parameters. Since a combination of clinical and histopathology parameters are better in predicting renal outcomes, performing renal biopsies should be encouraged in LN.
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