Gender difference in crescentic glomerulonephritis; an eleven-year single-center study

and outcome. Objectives: This study was designed to compare demographic, laboratory, and renal biopsy findings of patients with crescentic glomerulonephritis among males and females. Patients and Methods: This cross-sectional study compared age, gender, types of crescentic glomerulonephritis, serum creatinine, 24-hour proteinuria, the number of crescents, and percentage of fibrosis. Results: Of 169 patients with crescentic glomerulonephritis, 54.4% were males, and 45.6% were females. The mean age, serum creatinine level, and 24-hour proteinuria were 37.73±15.32 years, 2.06±1.35 mg/d, and 2084.82±1170.98 mg/d, respectively. Serum creatinine level and 24-hour proteinuria were not significantly different by gender. In addition, the number of crescents had no relationship with age and 24-hour proteinuria; however, it had a significant direct relationship with serum creatinine. Conclusion: According to our study, lupus nephritis affected women more than men, while other forms of crescentic glomerulonephritis were more common in males. Depending on the population, a significant relationship between the number of crescent and serum creatinine was detected. The mean age of females with crescentic glomerulonephritis was significantly lower than males. ABSTRACT


Introduction
Crescentic glomerulonephritis is a severe type of glomerulonephritis characterized by more than 50% crescents in renal biopsy, and leads to glomerular demolition and terminates to end-stage renal disease (ESRD) in a short period (months to weeks).Crescentic glomerulonephritis is not common however it is a rapidly progressive disease and is associated with several morbidities.This pattern appears in 10-15% of glomerulonephritis and is more common in rapidly progressive diseases (1).
The crescent is a hyperplastic lesion occupying more than 10% of the Bowman's space.Histopathologically, these lesions are glomerular damage due to parietal epithelial cell hyperplasia, leads to extra-capillary proliferation.Finally, this condition resulted to the reduction of Bowman's space causes a decrease in glomerular filtration rate (2).
Crescentic glomerulonephritis is categorized into three groups based on immunofluorescence microscopy findings.The first is anti-glomerular basement membrane (anti-GBM) disease or Goodpasture syndrome.

Original Article
Journal of Nephropathology, Vol x, No x, xx 2023 https://nephropathol.com 2 Immune-complex glomerulonephritis is the second type, and it includes conditions like lupus nephritis and immunoglobulin A nephropathy (IgA nephropathy).Third, pauci-immune glomerulonephritis is also known as nephritis associated with antineutrophil cytoplasmic autoantibody (ANCA) (3).
In anti-GBM disease, autoantibody against collagen type IV causes linear deposition along the glomerular basement membrane.Around 10-15% of crescentic glomerulonephritis is an anti-GBM disease.Goodpasture syndrome usually appears as rapidly progressive glomerulonephritis with or without pulmonary involvement which can leads to ESRD (4).
Pauci-immune glomerulonephritis is a common type of crescentic glomerulonephritis (65-70%).There is no immune deposition in immunofluorescence microscopy.In addition, it is usually associated with anti-neutrophil cytoplasmic autoantibody (ANCA-associated).Based on previous studies, pauci-immune glomerulonephritis is more common in old patients (7).
According to previous studies, clinical manifestations, outcomes, and prognosis are different in each kind of crescentic glomerulonephritis (7).This study was conducted to assess the risk factors that affect the chronicity and severity of crescentic glomerulonephritis in the Iranian population among males and females.

Objectives
We aimed to study the risk factors of crescentic glomerulonephritis in males versus females.

Study design
This cross-sectional study was conducted in Isfahan from July 2011 until April 2022.This study is the extension of our previous investigation in 2015 on 87 crescentic glomerulonephritis (8).In this study focused on the gender difference of this disease.This study was conducted on consecutive sampling to collect data from 169 patients with crescentic glomerulonephritis.
Patients with incomplete laboratory data and renal biopsy reports did not enter.Patients with other medical diseases (such as diabetes or amyloidosis) were excluded from the study.
Each patient had two samples; one for immunofluorescence study and another for light microscopy.For light microscopy, renal tissues were fixed in 10% formalin for sectioning.Afterward, tissues were prepared by paraffin blocks, cut into 3 µm, and stained with periodic acid Schiff, hematoxylin and eosin, Jones methenamine silver, and Masson's trichrome.Immunofluorescence samples were stained for IgA, IgM, IgG, C3, and C1q antibodies.
The full-house pattern (abundant granular deposits of C1q, IgG, and C3) approved the diagnosis of lupus nephritis.Accordingly, the definitive diagnosis of IgA nephropathy was accepted with the presence of granular IgA and C3 in the absence of C1q.Meanwhile, ANCAassociated glomerulonephritis was detected by the absence of IgG, C1q, and IgA deposition.In ANCA-associated glomerulonephritis few C3 deposition were interpreted as non-specific.Accordingly, linear deposition of IgG on the glomerular basement membrane was characteristic of Goodpasture syndrome.The granular deposition of C3 and IgG is considered as cryoglobulinemia in the mesangium and endocapillary space, along with morphological features and clinical data.Isolate deposition of C3 and the starry sky were characteristic of PSGN across with histological features and clinical findings.Finally, in Henoch-Schönlein purpura depositions of IgA and fibrin were existed.

Data analysis
Patient demographic information, including age, gender, serum creatinine, 24-hour proteinuria, number of crescents, and fibrosis percentage, were entered into SPSS software (version 25).Data were presented as means ± standard deviation or frequency (percentage) for continuous and categorical variables.The Kolmogorov-Smirnov test was conducted to evaluate the normal distribution for continuous variables.The chi-square test was conducted to compare genders, since the independent t-test was conducted to compare the mean continuous variables between the different crescents.A level of less than 0.05 was considered significant in all analysis.

Results
In this study, out of 169 patients with crescents, 54.4% were men, and 45.6% were women, with a mean age of 37.73 ± 15.32 years.
Our sample included 47.3% IgA nephropathy,37.9%lupus nephritis, 11.2% vasculitis, and Henoch-Schönlein purpura, since 3.6% were other diseases, including cryoglobulinemia (one patient), Goodpasture syndrome (four patients), and PSGN (one patient) (Table 1 1).Moreover, our study showed no significant correlation between the number of crescents and age or 24-hour proteinuria; however, a significant direct correlation between the number of crescents and serum creatinine was found (P < 0.001 and correlation coefficient = 0.393; Table 2).
There was no significant difference between serum creatinine, 24-hour proteinuria and fibrosis percentage among males and females (P > 0.05; Table 3).
Our results showed that females were more likely to have lupus nephritis while males were more likely to have other disorders (P < 0.05).Females' average age was 34.01±11.90years, which was significantly lower than that of males, with a mean of 40.85±17.14years (P < 0.001).In addition, the percentage of age younger than 40 years in females was significantly higher than in males (P value<0.001;Table 3).
Moreover, 24-hour proteinuria in younger patients with a mean of 2269.63 ± 1336.02 mg/d was significantly higher than in older ones with a mean of 1789.14 ± 763.18 mg/d (P = 0.009).However, mean serum creatinine and fibrosis percentage in young and old patients had no significant difference (P > 0.05; Table 4).
In comparison, crescents in lupus patients were more common in younger (age below 40 years old; 45.2%) while it was more common in older patients (age over 40 years old) in vasculitis (16.9%) and Henoch-Schönlein purpura (6.2%), and also IgA nephropathy (50.8%;Table 4).

Discussion
In China, epidemiologic data on crescentic glomerulonephritis accounted for 3.73%.This rate is higher than previously stated in this country (7,9).No precise statistics on the prevalence of this condition in Iran are available.Our study on crescentic glomerulonephritis in Iranian patients for eleven years showed that crescentic glomerulonephritis of type II was predominated (lupus and IgA nephropathy).Moreover, females were more likely to have lupus nephritis, which was more common in younger than 40 years.We also found, 24-hour proteinuria in younger patients was significantly higher than in older patients.Several other investigations had indicated that pauci-immune crescentic glomerulonephritis was the most common form (10)(11)(12)(13).One study also noted that the immune complex type was as common as the pauciimmune type.In type II crescentic glomerulonephritis, IgA nephropathy was the most common primary disease, which is consistent with our results (14).We think that the geographical location and timing of the investigation may have influenced the variation in prevalence.
We concluded that younger crescentic lupus patients had more proteinuria.Chen et al found that proteinuria did not significantly correlate with renal outcome (15).
Recently, Chen et al in a study on 158 IgA nephropathy patients, evaluated the relationship between crescentic glomerulonephritis and several factors.They found no relevant correlation between age and crescent count, however a meaningful direct correlation between the number of crescents and serum creatinine was seen.This finding was consistent with our study.They also found a direct relationship between 24-hour proteinuria and the number of crescents, while our study did not mention it (16).
In another study from India, most individuals with crescentic glomerulonephritis had pauci-immune, which was more common in men, since IgA nephropathy was the most common type of immune complex crescentic glomerulonephritis, followed by post-infectious glomerulonephritis (PIGN) and lupus nephritis (17).
In another study from China on 528 patients, crescentic glomerulonephritis was seen more in females (60.6%), and lupus nephritis had the highest prevalence.It was followed by pauci-immune crescentic glomerulonephritis and IgA nephropathy, respectively (7).
According to the study by Nakakita et al in Japan on 256 patients, the mean serum creatinine in crescentic glomerulonephritis with immune-complex deposition (lupus and IgA nephropathy) had a significant difference with ANCA-related crescentic glomerulonephritis (vasculitis).However, there was no significant difference of 24-hour proteinuria in both groups was seen.In their research, the crescent percentage in ANCA-related crescentic glomerulonephritis was higher than immunecomplex deposition glomerulonephritis.Their oneyear follow-up indicated a poor prognosis in ANCA-related glomerulonephritis.Correspondingly, global glomerulosclerosis and GFR were important predictors of the prognosis.They showed that IgA nephropathy had the highest prevalence, and lupus nephritis was more common in females.Likewise, the mean age of microscopic polyangiitis was 64 years, while the mean age of the immune-complex deposition group was 34 years old.Their findings were consistent with the current study; as a result, most lupus patients were under 40 years old, while most vasculitis patients were over 40 years old (5).

Conclusion
Our study on 169 individuals with crescentic glomerulonephritis showed that, 45.6% of patients with lupus nephritis were female, and women generally had a lower mean age than men.Furthermore, no significant difference was observed in 24-hour proteinuria, creatinine, and fibrosis percentage in either gender.
In this study, 47.3% had IgA nephropathy, 37.9% had lupus nephritis, and 11.2% had vasculitis and Henoch-Schonlein purpura.Furthermore, our research showed that younger patients had more crescents (below 40 years old).Additionally, this group had considerably higher 24-hour proteinuria, and the number of crescents demonstrated a strong connection with serum creatinine.

Limitations of the study
This research was conducted in a single laboratory and required further investigation by larger samples.

Table 1 .
Demographic and clinical characteristics of studied patients

Table 2 .
Correlation between the number of crescents and the study