Clinical and laboratory findings versus results of renal biopsy: Evaluation the diagnostic value in patients with lupus nephritis

The current gold standard method for diagnosing lupus nephritis is biopsy and histopathology, although biopsy is an invasive procedure and has complications such as bleeding, venous arterial fistula, and infection. Moreover, it is difficult to repeat[5, 6]. Rapid advances have been made in basic sciences and need to be applied in clinical diagnosis. This study was designed to promote and the use of non-invasive, low-cost, easy methods to diagnose and follow-up on treatment response. The aim of this study was to determine whether laboratory findings are consistent with those of kidney biopsy for biopsy classification. Original Article Open Access

Kidney involvement is a major cause of death and disability in patients with systemic lupus erythematosus (SLE). Early and accurate determination of the type of involvement is essential in choosing the appropriate treatment for these patients. The current study aimed to determine whether laboratory findings are consistent with kidney biopsy for biopsy classification. This descriptive analytic cross-sectional study was performed on 17 patients with SLE admitted to rheumatology and nephrology departments. All patients underwent renal biopsy and received appropriate treatment according to the reported pathology. Data analysis was performed using SPSS software version 25. The participants comprised 14 females and 3 males with a mean age of 32.23±11.12 years. The findings of this study showed that mean serum C3 and 24-hour urine protein concentrations were significantly different between the four studied groups according to the type of kidney pathology (p=0.042, p=0.041; respectively). No significant relationship was found between pathological findings and clinical signs, demographic information, and other laboratory findings (p>0.05). Based on the findings of the present study, it can be concluded that renal biopsy is the most accurate method available for the diagnosis and classification of lupus nephritis. Nonetheless, renal biopsy has limitations including side effects, the need for an experienced pathologist, and suboptimality in some cases; renal biopsy was suboptimal in three cases of the current study. Therefore, noninvasive faster methods with high efficacy should be sought.

Results________________________________
In the present study, 20 SLE patients with kidney biopsy initially began the study, but three of them were excluded due to inappropriate biopsy. Ultimately, 3 males and 14 females with a mean ± SD age of 32.23 ± 11.12 years completed the study. The demographic information of the patients, such as sex, age, laboratory data such as Anti-dsDNA, C3, C4, HTN, WBC, Hb, PLT, Cr, ESR, CRP, and 24-hour urine protein as well as kidney biopsy results were collected. Next, the relationship between laboratory and demographic findings with pathology results was assessed.
The percentages of males and females were 17.65% and 82.35%, respectively. The frequency of edema and HTN positivity in the studied patients was 35.29% and 29.41%, respectively. According to Table 1, the mean and standard deviation of Anti-dsDNA, C3, C4, WBC, Hb, PLT, Cr, ESR, CRP, and urinary protein 24 are shown.
The results showed that sex, age, edema, and HTN were not significantly associated with the pathological findings. As shown in Table 2, there was no significant difference between the groups in the laboratory findings of lupus activity. It should be noted, however, that there was a significant relationship between serum C3 level and 24hour urinary protein pathological findings.

Study population
The study population of this descriptive-analytical cross-sectional study comprised lupus patients with renal involvement who were candidates for kidney biopsy and admitted to the rheumatology or nephrology department of Imam Khomeini Hospital during 2018-2019. According to the one-year census, all patients with lupus nephritis who were candidates for biopsy were included in the study. Inclusion criteria included patients who were diagnosed with SLE according to the 1987 ACR Lupus Diagnostic Criterion and had renal involvement based on U/A and 24hour urine protein results. Exclusion criteria included having a co-morbid history of drug abuse and pregnancy. The protocol of the study was approved by the Ethics committee of Tehran University of Medical Sciences (Code: IR.TUMS.IKHC.REC.1397.243).

Statistical Analysis
All statistical analyses were performed using SPSS software version 25 (SPSS Inc., Chicago, IL) at both descriptive and analytic levels. The normal distribution of quantitative data was investigated using the Kolmogorov-Smirnov Z test, and then one-way analysis of variance (ANOVA) and Kruskal-Wallis tests were employed to compare the four groups with normal and non-normal distribution, respectively. A p value of < 0.05 was considered as statistically significant.

Discussion_____________________________
The type of renal involvement in SLE is an important determinant of prognosis in these patients. It is essential to determine early the correct type of involvement so as to choose the appropriate treatment for these patients. The most correct way to determine the type of kidney lesion is through pathological examination of kidney tissue [7]. Because of its invasiveness, related complications, and a lack of access to necessary facilities (experienced pathologists, equipment, etc.), use of this method is not possible for all physicians [8]. The present study was performed to determine the relationship between appropriate clinical and paraclinical criteria by determining the type of renal involvement in 14 female and 3 male SLE patients with renal involvement. The findings of this study showed that the means of C3 and 24-hour urinary protein were significantly different among the 4 studied groups. No significant relationship was found between renal pathology findings and clinical signs, demographic information, or other laboratory findings. Renal biopsy was suboptimal in three cases, indicating this is one of the limitations of pathology assessments of lupus nephritis patients.
Saadati et al. [9] investigated the relationship between clinical symptoms and renal pathology in patients with systemic lupus erythematosus. Of the 34 patients studied, 32 were female and 2 were male. The mean age of patients at the time of diagnosis was 25.12 ± 12.05 years. All patients had kidney involvement at the time of referral. The most common pathological renal lesion in these patients was diffuse proliferative glomerulonephritis. Class 4 lupus nephritis was the most important factor in determining the prognosis. The sex ratio in the present study was similar to that in the study of Saadati et al., however unlike the study of Saadati et al., the current study did not examine the prognoses of patients.
Ebadi et al. [10] evaluated the epidemiology of lupus nephritis in 40 patients admitted to Imam Khomeini Hospital. The age range of patients in their study was between 12-45 years with a mean age of 21.5 years, and the maximum frequency in the second decade of life was 48.6%. In their study, 86.5% of patients were female and 13.5% were male. Butterfly rash and fever were the most Rheumatology Research., Vol. 5, No. 3, July. 2020 common clinical symptoms with 62.5% and 57.5%, respectively. The most common pathology and symptoms of renal involvement were class IV with 37.8% and hematuria with 88.9%, respectively, and. 97.1% of patients had renal involvement. Pulse therapy with corticosteroids and cyclophosphamide was effective in 50% of cases in pathology IV in preventing chronic renal failure. 100% of patients with class III lupus nephritis had poor prognosis. In the present study, contrary to the results of Ebadi  The results of their study showed that 5, 8, 10, and 7 cases had grade 3, grade 3 and 4, grade 4, and grade 5 biopsy results, respectively. The relationship between age, proteinuria, ESR, and biopsy result was significant. The results of this study contradict the findings of the present study which showed no significant relationship between age, ESR, and biopsy results. The study has a potential limitation in its sample size. Unfortunately, despite meeting the criteria for renal biopsy, some patients were dissatisfied for renal biopsy.