Background/Purpose: To analyze the correlation between clinical and laboratory data and type of histological injury in a cohort of patients with lupus nephritis (LN).

Methods: The sample comprised 243 patients with SLE treated between 1980 and 2013 at a tertiary university hospital that does not attend pediatric populations. Patients were registered in a specific database. Patients diagnosed with LN classes 2-5 according to the WHO classification or the ISN/RPS classification (in use since 2004) were selected for analysis. In each case, the presence of arterial hypertension, renal insufficiency (RI), nephrotic syndrome (NS), hematuria, and cylindruria was assessed at the time of the biopsy; 24-h urine protein value was also recorded.

The specificity, sensitivity, PPV, NPV, LR +,  LR-, and accuracy  for each of the clinical and laboratory data in order to diagnose the different histological types of LN.

Results: The diagnoses were: a) Class II Mesangial proliferative lupus nephritis, 45 cases (35%); b) Class III Focal lupus nephritis, 16 (13%); c) Class IV Diffuse lupus nephritis 49 (39%), and d) Class V Membranous lupus nephritis,16 (13%).

The mean levels of proteinuria were: a) class II; 1.62 g/24 h; b) class III: 1.53 g/24 h; c) class IV; 2.12 g/24 d) class V; 5.15 g/24 h. The only significant differences observed were between LN class V and the other histological types of LN. Five patients had proteinuria below 0.5 g/24 h (3 class II and 2 class IV) and 12 had proteinuria 0.5-1 g/24 (3 class II, 3 III, 4 IV and 2 class V).

The discriminative values of other clinical and laboratory data for the diagnosis of the different types of LN are shown in Table 1.

 

	Sensitivity	Specificity	PPV	NPV	LR+	LR-	Accuracy
CLASS II Renal insufficiency Arterial Hypertension Nephrotic syndrome Hematuria Cylindruria	– 4% 4% 18% 69% 4%	– 83% 78% 54% 40% 81%	– 13% 10% 18% 39% 12%	– 61% 59% 54% 70% 61%	– 0.26 0.20 0.39 1.14 0.24	– 1.16 1.23 1.51 0.79 1.17	– 0.547 0.515 0.412 0.500 0.539
CLASS III Renal insufficiency Arterial Hypertension Nephrotic syndrome Hematuria Cylindruria	– 6% 6% 6% 56% 13%	– 86% 83% 60% 35% 87%	– 6% 5% 2% 11% 13%	– 86% 86% 81% 85% 87%	– 0.46 0.36 0.16 0.87 0.98	– 1.09 1.13 1.56 1.23 1.00	– 0.761 0.730 0.531 0.380 0.777
CLASS IV Renal insufficiency Arterial Hypertension Nephrotic syndrome Hematuria Cylindruria	– 20% 35% 53% 61% 22%	– 94% 96% 75% 35% 94%	– 67% 85% 58% 38% 69%	– 65% 70% 72% 59% 65%	– 3.14 8.90 2.15 0.94 3.46	– 0.85 0.68 0.62 1.11 0.83	– 0.650 0.722 0.666 0.452 0.658
CLASS  V Renal insufficiency Arterial Hypertension Nephrotic syndrome Hematuria Cylindruria	– 19% 0% 63% 63% 13%	– 88% 82% 68% 36% 87%	– 19% 0% 22% 13% 13%	– 88% 85% 93% 87% 87%	– 1.59 0.00 1.96 0.98 0.98	– 0.92 1.22 0.55 1.03 1.00	– 0.793 0.714 0.674 0.396 0.777

Parameters with a high LR + (greater than 3) and an acceptable diagnostic accuracy were the presence of RI, arterial hypertension and cylindruria in LN class IV. The presence of NS in classes IV and V also had a relatively high LR +. However, at the time of diagnosis or during follow-up, eight patients with LN class II had NS (excluding those patients with nephrotic-range proteinuria undergoing class transformation). Although uncommon, the presence of cylindruria was also observed in LN class II (one patient), class III (2) and type V (2) .

In LN class II, none of the clinical and laboratory data had a LR- high enough (<0.5 to 0.3) to be a useful parameter to discard it.

Conclusion: In LN, only class IV and to a lesser extent class V present a good correlation between the clinical/ laboratory and histological data. In general, clinical/laboratory data cannot predict the type of histological lesion. In our experience, more than half of patients with mild proteinuria (below 1 g/24 h) presented advanced forms of LN (classes III, IV or V).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/lupus-nephritis-clinicopathological-correlation-in-126-biopsies/