Clinicopathologic features and long-term prognosis of hepatitis B virus-associated glomerulonephritis: a retrospective cohort study

Background Hepatitis B virus-associated glomerulonephritis is a common form of secondary glomerulonephritis in China. However, the clinicopathological features and long-term prognosis of Hepatitis B virus-associated Glomerulonephritis remain only partially known. Methods Biopsy-proven Hepatitis B virus-associated Glomerulonephritis patients were enrolled between November 1994 and December 2013 at our center. The composite endpoints were doubling serum creatinine, end-stage renal disease, or death from renal disease during follow-up. The clinicopathological features and predictors of the long-term prognosis of Hepatitis B virus-associated Glomerulonephritis patients were explored. Results The median age of the 259 Hepatitis B virus-associated Glomerulonephritis patients was 31.0 years (IQR 24.0–40.0), and 71.0% were males. Among the patients, 45.2% presented with nephrotic syndrome, and 45.9% presented with proteinuria combined with hematuria. The two most prevalent pathological patterns were IgA nephropathy (27.0%) and membranous nephropathy (27.0%). The mean follow-up period was 68.8 ± 46.9 months. The 3-, 5-, and 10-year clinical event-free survival rates were 93.4%, 85.2%, and 70.3%, respectively. Multivariable Cox regression analysis showed that hypertension (HR 2.580, 95% CI 1.351–4.927, P = 0.004), hyperuricemia (HR 2.101, 95% CI 1.116–3.954, P = 0.021), glomerulosclerosis (P = 0.001), and intrarenal arterial lesions (P = 0.041) were independent predictors of composite clinical event endpoint. Patients in the antiviral therapy group exhibited a significantly better prognosis compared to those who received no antiviral therapy (log-rank χ2 = 5.772, P = 0.016). Conclusion Hepatitis B virus-associated Glomerulonephritis has specific clinicopathologic features and should not be considered a benign disease in adults. Hypertension, hyperuricemia, glomerulosclerosis, and intrarenal arterial lesions were independent predictors of the long-term prognosis in Hepatitis B virus-associated Glomerulonephritis patients. Antiviral therapy could be effective in improving the long-term prognosis of Hepatitis B virus-associated Glomerulonephritis patients. Graphic abstract Supplementary Information The online version contains supplementary material available at 10.1007/s40620-023-01685-x.


Introduction
Many studies have demonstrated that Hepatitis B virusassociated glomerulonephritis (HBV-GN) is the most prevalent extrahepatic manifestation of HBV infection.Hepatitis B virus-associated glomerulonephritis was first reported in 1971 by Combes et al. [1].Since then, the relationship between HBV infection and nephropathy has received widespread attention.Recently, China has made great progress with universal vaccination for hepatitis B, which has significantly decreased the prevalence of HBV-GN.However, HBV-GN is still a common form of secondary glomerulonephritis among the Chinese population [2,3].
Hepatitis B virus antigen deposition in the glomeruli suggests that complement activation induced by immune complex deposition plays a critical role in HBV-GN glomerular injury [4].In most patients, HBV-GN presents as a chronic latent disease manifesting as nephrotic syndrome, while in others, it presents mild to moderate proteinuria and hematuria [5].Many studies have reported that patients with HBV infection have different types of glomerulonephritis characterized by their pathological patterns, including membranous nephropathy (MN), membranoproliferative glomerulonephritis (MPGN), mesangial proliferative glomerulonephritis (MsPGN), IgA nephropathy (IgAN), minimal change disease (MCD), and focal segmental glomerulosclerosis (FSGS) [6][7][8].
Several studies have reported that spontaneous remission of HBV-associated membranous nephropathy (HBV-MN) is common in children, but rare in adults [6,7,9].Although HBV-GN is common among the Asian population, including China, few studies focusing on the clinicopathological features and the long-term prognosis of HBV-GN in Asian populations have been conducted thus far.Therefore, this retrospective cohort study aims to elucidate the clinicopathological features, the long-term prognosis, and risk factors for the clinical event endpoint in 259 HBV-GN patients over ten years at our center.

Patients
This retrospective cohort study included 333 consecutive adult patients diagnosed with HBV-GN using renal biopsy at Fuzhou General Hospital of Nanjing Military Command (currently referred to as 900 Hospital of the Joint Logistics Team, PLA, Fuzhou General Clinical Medical College of Fujian Medical University).This study analyzed clinical data of patients who attended the center for treatment between November 1994 and December 2013.Patients with a follow-up period of more than 12 months were included in the research as of March 2015.Patients were excluded from this study if (1) they had incomplete clinical and pathologic data (n = 5), (2) were lost to followup (n = 57), and (3) the follow-up was less than 12 months (n = 12).The diagnostic criteria for HBV-GN were (1) HBV antigen-positive serum, (2) glomerular nephritis, excluding other secondary glomerular diseases, and (3) HBV antigens detected in kidney tissue by immunohistochemical staining [10].On the basis of the inclusion and exclusion criteria, 74 patients were excluded, and 259 were included in our study.

Clinical data collection
The demographic and laboratory characteristics of subjects include age, gender, systolic blood pressure, diastolic blood pressure, uric acid, hemoglobin, serum creatinine, estimated glomerular filtration rate (eGFR), and chronic kidney disease (CKD) stages.The study also recorded the patient's serum albumin, 24-h urinary protein, alanine transaminase, aspartate transaminase, and HBV serum markers.In addition, we evaluated anemia following the World Health Organization (WHO) criteria [11], and eGFR was evaluated using the CKD-EPI formula [12].After determining the laboratory characteristics of the patients, the patients were divided into four categories according to clinical manifestations: nephrotic syndrome, proteinuria alone, proteinuria combined with hematuria, and hematuria alone.
Medications including antiviral drugs, renin-angiotensin system (RAS) blockers, corticosteroids, and additional immunosuppressive agents were recorded.A total of 179 HBV-GN patients were treated with RAS blockers, except in the case of contraindications and no indication for RAS blocker use.One hundred sixty-one HBV-GN patients had received antiviral therapy, including 124 patients who had received antiviral therapy alone and 37 patients who had received combined antiviral and immunosuppressant therapy (corticosteroids and/or immunosuppressive agents).In addition, for patients who had received combined antiviral and immunosuppressant therapy, the antiviral therapy continued for 6 months after the withdrawal of immunosuppressant therapy.

Endpoint event definition
The composite clinical event endpoint was defined as doubling serum creatinine, end-stage renal disease, or death from renal disease during follow-up.On the other hand, "Death from renal disease" was defined as death caused by a complication of renal failure (e.g., hyperkalemia, heart failure, arrhythmia, and cerebrovascular events), excluding death from non-renal causes (e.g., car accident, tumor).

Statistical analyses
Categorical data were expressed as frequencies and percentages.The normally distributed continuous data were presented as the mean ± standard deviation, and non-normally distributed continuous data were presented as the median and interquartile range (IQR).Categorical data were analyzed using the chi-squared (χ 2 test) or Fisher's exact test as appropriate.Continuous data were compared using the t-test, Mann-Whitney U-test, Kruskal-Walls H-test, or one-way ANOVA as appropriate.This study used Spearman's rank correlation coefficient to analyze correlations.In addition, the cumulative clinical event-free survival rate was estimated using the Kaplan-Meier method and compared using the log-rank test.Hazard ratios (HRs) were calculated using the Cox proportional hazards model with 95% confidence intervals (CIs) to identify the risk factors for long-term prognosis.In this study, factors with a p-value greater than 0.05 in the univariate analysis were included in the multivariate Cox regression model.This study combined patients with MCD and FsPGN because their sample size was small and had similar pathological features.Statistical analyses were performed using SPSS version 22.0 (Chicago, IL, USA).The significance level was set at p < 0.05 (2-tailed).

Correlations between renal pathological types and clinical manifestations in HBV-GN patients
The most common pathological types were IgAN (27.0%) and MN (27.0%), followed by MsPGN, MPGN, MCN/ FsPGN, SGN, and FSGS.Most patients presented with nephrotic syndrome (45.2%) or proteinuria combined with hematuria (45.9%), while only a small proportion presented with proteinuria alone (6.6%) or hematuria alone (2.3%).Patients with nephrotic syndrome had a higher MN, MPGN, MCD/FsPGN prevalence, and lower IgAN prevalence than proteinuria combined with the hematuria group, as shown in Table 2.

Different pathological types can predict HBV-GN prognosis
During the follow-up period, nine (3.5%) patients experienced a doubling of serum creatinine, 27 (10.4%)patients had end-stage renal disease, and 18 (6.9%)patients died from renal disease.In addition, the study also found that five patients died from non-renal causes, including liver cancer (n = 1), leukemia (n = 1), and car accidents (n = 3).
The composite clinical event endpoint was found in 23.1% of patients in the nephrotic syndrome group, 23.5% in the proteinuria alone group, 19.3% in the proteinuria combined with hematuria group, and in 0% of the hematuria alone group.In the Kaplan-Meier analysis, the clinical event-free survival rate was not statistically significant among the four clinical categories (log-rank χ 2 = 1.777,P = 0.620).

Hypertension, hyperuricemia, glomerulosclerosis, and intrarenal arterial lesions were independent predictors of HBV-GN prognosis
Kaplan-Meier analysis revealed that hypertension, hyperuricemia, anemia, glomerulosclerosis, intrarenal arterial lesions, and tubulointerstitial lesions were associated with a lower cumulative clinical event-free survival rate, as shown in Fig. 4.

Antiviral therapy may help to improve the prognosis of HBV-GN patients
The demographic and clinical data at baseline of both the antiviral therapy group and no antiviral therapy group are shown in Table 1.There was no significant difference in RAS blocker use.Compared with those in the no antiviral therapy group, the patients in the antiviral therapy group had shorter follow-up periods and fewer FSGS patients.Patients in the antiviral therapy group exhibited a significantly better prognosis compared to those in the no antiviral therapy group (log-rank χ 2 = 5.772, P = 0.016), as shown in Fig. 5A.
Compared with those in the combined antiviral and immunosuppressant therapy group, the antiviral therapy alone group had more FSGS patients.Other detailed baseline characteristics are presented in Supplementary Table 1.There was no significant difference in the long-term prognosis between the antiviral therapy alone group and the   3 Long-term prognosis of patients according to different pathological subtypes.Log-rank analysis showed that the clinical eventfree survival rate was statistically significant among different pathological subtypes (χ 2 = 67.106,P < 0.001) combined antiviral and immunosuppressant therapy group (log-rank χ 2 = 1.169,P = 0.280), as shown in Fig. 5B.

Discussion
In this study, we explored the risk factors influencing the development of clinical events in 259 HBV-GN patients in China.It represents the largest number of HBV-GN cases with follow-up information in the world.This study found that the 3-, 5-, and 10-year clinical event-free survival rates were 93.4%, 85.2%, and 70.3%, respectively.The median time for the patients to reach the composite clinical event endpoint was 188 months.To our knowledge, only one study has explored the prognosis of HBV-MN in adult patients [6].With an average follow-up of 73 months, they found that 6 patients (28.6%) with HBV-MN developed renal failure, and 2 (9.5%) required maintenance dialysis.
Our study identified IgAN (27.0%) and MN (27.0%) as the most common pathological types of HBV-GN.These findings were consistent with the results of studies conducted in Thailand, Hong Kong, and South Africa [6][7][8].On the contrary, one study in Japan reported that MPGN is the prevalent pathological type of HBV-GN [15].In addition, another study in China reported that MsPGN is the prevalent pathological type of HBV-GN [16].
Many studies have demonstrated that the prognosis of HBV-GN depends on the pathological subtype.Our study found that patients with MCD/FsPGN had an excellent prognosis, and patients with MN and MsPGN had a better prognosis than those with IgAN.However, patients with MPGN, FSGS, and SGN had poor long-term prognoses, possibly due to a higher incidence of renal insufficiency and hypertension.Zhang et al. [16] reported that patients with CKD stage 3 and above accounted for 11.6% (38/329) of HBV-GN patients in northeastern Chinese adults.However, patients with MPGN (12/38, 31.6%) and MsPGN (8/38, 21.1%) were more prone to develop renal failure among the 38 cases.Different regions, inclusion criteria, immunosuppressive and antiviral therapy indications, and RAS blockers or endpoint definitions may account for these discrepancies.
In this study, the nephrotic syndrome group and proteinuria combined with hematuria group accounted for the largest number of HBV-GN patients (236/259, 91.1%).Patients with IgAN often presented with persistent hematuria and proteinuria, whereas most HBV-GN patients with MN exhibited nephrotic syndrome with or without renal dysfunction, which was consistent with previous studies [6,8].Usually, patients with nephrotic syndrome have a worse kidney prognosis than those without nephrotic syndrome.However, this study found that the long-term prognosis of patients with different clinical categories was similar, suggesting that the HBV-GN prognosis was based more on pathological results than on clinical presentation.
Univariate Cox regression analysis demonstrated that hypertension, hyperuricemia, anemia, increased serum Fig. 4 The cumulative event-free survival rate in HBV-GN patients categorized by hypertension, hyperuricemia, anemia, glomerulosclerosis, intrarenal arterial lesions, and tubulointerstitial lesions.Log-rank analysis showed that there were significant differences in event-free survival rate between A hypertension and no hypertension (χ 2 = 24.600,P < 0.001), B hyperuricemia and no hyperuricemia (χ 2 = 13.159,P < 0.001), C anemia and no anemia (χ 2 = 12.468, P < 0.001) and among (D) no and mild degree of glomerulosclerosis (GS), moderate degree of GS and severe degree of GS (χ 2 = 57.240,P < 0.001), E no and mild degree of intrarenal arterial lesions, moderate degree of intrarenal arterial lesions and severe degree of intrarenal arterial lesions (χ 2 = 18.435,P < 0.001), F no and mild degree of tubulointerstitial lesions, moderate degree of tubulointerstitial lesions and severe degree of tubulointerstitial lesions (χ 2 = 54.449,P < 0.001) Previous studies have found that the prevalence and severity of CKD are associated with uric acid levels [20,21].Our previous study demonstrated that hyperuricemia was associated with hypertension, elevated serum creatinine, glomerulosclerosis, and renal tubular interstitial injury in HBV-GN [5].This cohort study identified glomerulosclerosis as an unfavorable prognostic risk factor.Patients with concomitant glomerulosclerosis in pathological findings, such as FSGS and SGN, had a poor prognosis.Our previous study showed that intrarenal arterial lesions were correlated with higher blood pressure, reduced renal function, and more severe interstitial injury in HBV-GN patients [10].The study also found that intrarenal arterial lesions strongly impacted the renal prognosis of HBV-GN [10].These findings were reported for other renal diseases, such as IgAN and lupus nephritis [22,23].
To date, there are no reliable data on the long-term prognostic effect of the treatment protocol in patients with HBV-GN.A previous meta-analysis showed that antiviral therapy against HBV infection significantly reduced proteinuria in HBV-MN patients [24].Our study confirmed that antiviral therapy significantly improved the long-term prognosis of HBV-GN patients, but the baseline differences may have induced a bias.In addition, a meta-analysis found that combined antiviral and immunosuppressant therapy could reduce proteinuria in HBV-GN patients without HBV reactivation [25].In our study, patients in the combined antiviral and immunosuppressant therapy subgroup had less pathological severity compared with the antiviral therapy alone group, however, there was no additional benefit observed in long-term prognosis in patients treated with combined antiviral and immunosuppressant therapy compared with antiviral therapy alone.
This study has several limitations.First, it combined several variables or groups with small sample sizes or similar pathological features, thus reducing the statistical power.Second, this is a single-center retrospective study.
In conclusion, this study explored the clinicopathological features and predictors of long-term prognosis in HBV-GN patients.Results showed that 29.7% of patients developed the composite clinical event endpoint within ten years.Hypertension, hyperuricemia, glomerulosclerosis, and intrarenal arterial lesions were independent predictors of the long-term prognosis in adult HBV-GN patients.Antiviral therapy could be effective in improving the long-term prognosis of HBV-GN patients.
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Fig. 2
Fig. 2 Long-term prognosis of HBV-GN patients.The median time to composite endpoint was 188 months

Table 1
Baseline characteristics of patients with HBV-GN SBP systolic blood pressure, DBP diastolic blood pressure, eGFR estimated glomerular filtration, UP urinary protein, ALT alanine transaminase,

Table 2
The relationship between clinical categories and pathological types of HBV-GN NS nephrotic syndrome, P proteinuria alone, H hematuria alone, P + H proteinuria combined with hematuria a P < 0.05 vs. NS group

Table 3
Univariate and multivariate analysis of risk factors for developing clinical events