Unhealthy Behaviors and Metabolic Indices of Chronic Kidney Disease in a HCV Hyperendemic Area: A Community-Based Study

Background: Hepatitis C virus (HCV) infection is related to a higher risk of chronic kidney disease (CKD). This study aimed to investigate the relationships between unhealthy behaviors, metabolic indices, and HCV with CKD. Methods: This cross-sectional study was conducted as part of a community health promotion program in the HCV hyperendemic area of Taiwan between March and December 2019. Multivariable logistic regression analyses adjusted for demographic and clinical characteristics were performed to investigate the association between CKD and HCV seropositivity. Results: A total of 2,387 patients completed the examination. HCV was related to a lower estimated glomerular ltration rate (eGFR), unhealthy dietary behaviors, and multiple metabolic indices including higher systolic blood pressure (SBP), glycosylated hemoglobin (HbA1c), and triglycerides (TG), and lower high-density lipoprotein (HDL). HCV was associated with a 44% higher risk of CKD compared to non-HCV (OR 1.44, 95% condence interval [CI] 1.05-1.98). Irregular exercise, waist circumference (WC), and higher HbA1c were signicantly associated with a higher risk of CKD after multivariable analysis. A low eGFR was signicantly associated with the severity of metabolic syndrome (MetS) in the HCV group (median eGFR of 86.4, 77.1, and 64.5 mL/min/1.73 m 2 for individuals with one, three, and ve MetS components, respectively). Conclusions: HCV seropositivity, metabolic distortion, and irregular exercise are signicantly associated with CKD. Effective treatment of HCV and aggressive health promotion of physical activity may prevent the occurrence of CKD. This community-based study was conducted in rural on the The cross-sectional data were drawn from annual health check-ups during a nurse-led community health promotion program conducted between March and December 2019. The inclusion criteria were patients 18 to 80-years-old who agreed to sign the informed consent form. Participants without laboratory data and informed consent forms were excluded.

between unhealthy behaviors, metabolic disturbances, and HCV with CKD.

Methods
This community-based study was conducted in rural areas on the western coast of Taiwan, in Yunlin County. The cross-sectional data were drawn from annual health check-ups during a nurse-led community health promotion program conducted between March and December 2019. The inclusion criteria were patients aged 18 to 80-years-old who agreed to sign the informed consent form. Participants without complete laboratory data and informed consent forms were excluded.
This study was approved by the Institutional Review Board (IRB NO: 201900222A3). The research assistants obtained informed consent from all participants. All research assistants had received two hours of questionnaire interview training by an investigator. Interviews with pilot participants con rmed a 90% rate of inter-rater reliability. All study participants completed a 10-minute interview using a structured questionnaire and donated a blood sample after fasting overnight for 8 hours. Data on the demographic and clinical characteristics of the study participants were collected, including gender, age, education level, dietary behaviors, irregular exercise, and substance use. Healthy dietary behaviors were de ned by a vegetable intake ≥ three portions per day (one portion is equivalent to 100 g edible vegetables), fruit intake ≥ two portions per day (one portion is equivalent to 100 g edible fruits), and water intake ≥ 1500 cc per day according to the daily dietary guidelines suggested by the Health Promotion Administration of Taiwan Ministry of Health and Welfare (11).
A patient was determined to be infected with HCV if the anti-HCV antibody test was positive, infected with hepatitis B virus (HBV) if the HBV surface antigen test was positive, or classi ed into the non-hepatitis group if both enzyme-linked immunosorbent assay tests were negative. In addition, subjects with HBV and HCV co-infection were excluded from the analysis.
Components related to metabolic syndrome included a WC ≥ 90 cm for males or ≥ 80 cm for females, SBP > 130 mmHg or DBP > 85 mmHg, HDL < 40 mg/dL for males or < 50 mg/dL for females, TG ≥ 150 mg/dL, and HbA1c ≥ 5.7%. Metabolic syndrome was diagnosed if three or more of the ve components were present (12-16).

Statistical analysis
The demographic, dietary and clinical characteristics of the study subjects in the hepatitis status groups (non-hepatitis vs. HBV vs. HCV) were compared using one-way analysis of variance for continuous variables or the Chi-square test for categorical variables. Pairwise comparisons were performed using Bonferroni adjustment if the overall difference was signi cant. The demographic, dietary and clinical characteristics of the study subjects with and without CKD were compared using the independent sample t-test for continuous variables or Chi-square test for categorical variables. A series of univariate logistic regression analyses were conducted to screen for factors potentially associated with CKD (de ned as eGFR < 60 mL/min/1.73 m 2 ). Variables with a signi cance level less than 0.15 were further incorporated into a multivariable logistic regression model with a backward elimination (17). All tests were two-tailed and P < 0.05 was considered statistically signi cant. Data analyses were conducted using IBM SPSS Statistics for Windows, version 25 (IBM Corp., Armonk, NY, USA).

Results
A total of 2,387 subjects with complete examination data were analyzed in this study, of whom 213 (8.9%) and 306 (12.8%) subjects were seropositive for HBV and HCV, respectively ( Table 1). The mean participant age was 64.1 years old (y/o); females accounted for 63.2% of all participants. The individuals in the HCV group were older (70.8 y/o), had a lower education level, were less likely to have healthy dietary behaviors, and were more likely to chew or consume betel compared to the HBV and non-hepatitis groups. In addition, the HCV group had higher SBP, HbA1c, and TG, and lower HDL, and were more likely to have metabolic syndrome. Higher AST and ALT, and lower eGFR were also noted in the HCV group. There were no differences in gender, WC, irregular exercise, smoking, and consumption of alcohol among the three groups (Table 1). "a" and "b" indicate signi cant difference versus the "Non-HBV & Non-HCV" and "HBV only" groups in the Bonferroni multiple comparison, respectively; Data were presented as mean ± standard deviation or frequency and percentage. "a" and "b" indicate signi cant difference versus the "Non-HBV & Non-HCV" and "HBV only" groups in the Bonferroni multiple comparison, respectively; Data were presented as mean ± standard deviation or frequency and percentage.
We further compared the characteristics of the subjects with and without CKD ( Table 2). The individuals with CKD were older, less likely to be female, had a lower education level, had poorer dietary behaviors, and were less likely to exercise regularly. Subjects with CKD also had a higher frequency of components of metabolic syndrome, including higher WC, SBP, HbA1c, and TG, lower DBP, and lower HDL. The prevalence of metabolic syndrome was higher in the CKD group than the non-CKD group. There were no differences in substance use among the two subgroups. Moreover, the CKD group had poorer liver function (ALT) and a higher prevalence of HCV (21.3% vs. 11.4%; Table 2). Data were presented as mean ± standard deviation or frequency and percentage; All variables were included in a series of univariate logistic regression analyses to investigate the factors potentially associated with CKD (  * Diastolic blood pressure was not included in the multivariable model due to its collinearity with systolic blood pressure; # AST was not included in the multivariable model due to its collinearity with ALT. As shown in Fig. 1, a greater reduction in renal function was associated with a higher number of MetS components in the subjects with HCV (one, three, and ve components of MetS associated with a median eGFR of 86.4, 77.1, and 64.5 mL/min/1.73 m 2 , respectively). Finally, the effect of regular exercise on the risk of CKD was analyzed in the groups strati ed by hepatitis status. The effect of irregular exercise on the risk of CKD was similar among the non-hepatitis, HBV, and HCV groups (Supplementary Table).

Discussion
In this community-based study conducted in an area where viral hepatitis is hyperendemic, HCV seropositivity was signi cantly related to CKD complicated with unhealthy dietary behaviors and multiple metabolic disturbances. Overall, 12.8% of all participants were HCV seropositive, and HCV seropositivity increased the risk of CKD by 44% compared to the non-hepatitis participants (OR 1.44, 95% CI 1.05-1.98), which is compatible with the results of a previous meta-analysis (HR 1.39, 95% CI 1.14-1.69) (6). From another perspective, effective HCV treatment could decrease the 30% risk of incidental CKD (5). Beyond the traditional risk factors for CKD, HCV infection may play a crucial role in progressive renal dysfunction, and early detection of HCV seropositivity during health check-ups represents an emergent issue in rural areas.
This study found patients with HCV and CKD exhibited deterioration in multiple metabolic indices, and MetS signi cantly increased the risk of CKD by 50% and was associated with a greater annual decline in eGFR (9, 18-21). A high prevalence of MetS (24.7-35%) in HCV cohorts was noted in previous studies (22)(23)(24); however, the rate of MetS among the HCV group was 58.8% in our study. Individuals with HCV had higher potential risks of CKD because of older age, lower HDL, and higher HbA1c, which also contribute to advanced vascular atherosclerosis and diabetic kidney disease (9,18,25,26). Individuals with HCV with MetS were 3.8 times more likely to fail anti-viral treatment than non-HCV subjects (27,28), and incomplete viral eradication can lead to CKD through extra-hepatic immune injury. Our study found that higher HDL could protect against CKD, while HCV eradication might cancel out the suppressive effect of chronic HCV infection on lipid metabolism (29).
Regular exercise was shown to improve physical performance and tness, cardiopulmonary function, and quality of life in patients with CKD (28-30). However, the effects of exercise on eGFR in current studies are con icting. Although a meta-analysis reported exercise led to an increase in eGFR and decreased BMI, but not HDL (7), other studies revealed exercise improved HDL and did not signi cantly change eGFR (30)(31)(32). Our study demonstrates that irregular exercise was an independent risk factor for CKD; however, the frequency of irregular exercise (average 69.5%) was extremely high, regardless of the presence or absence of either form of viral hepatitis. We also assessed the effect of irregular exercise in the patient groups strati ed by viral seropositivity, and found physical activity may provide additional bene ts in terms of maintenance of renal function in individuals with HCV and MetS comorbidity. Community health efforts are necessary to enhance education and promote physical activity because the average rate of irregular exercise is relatively high.
Dietary interventions have been proposed as an approach to improve CKD outcomes in the last decade. Healthy diets are considered to contain a low animal/vegetable protein ratio and high proportions of vegetables, legumes, and fruits (33,34). A plant-dominated low-protein diet of 0.6-0.8 g protein/kg/day composed of more than 50% plant-based sources has been suggested as a pragmatic and safe goal (34,35). Healthy dietary behaviors were associated with a lower risk of CKD and slower deterioration of renal function. On the contrary, a high-protein diet was associated with a 1.32-fold increased risk of rapid decline in eGFR (8, 36, 37). The effect of unhealthy dietary behaviors on individuals with HCV is rarely discussed in the literature. Higher dietary cholesterol intake was related to a higher risk of advanced liver brosis, and soy supplements were related to lower liver in ammation (38, 39). Thus, maintaining healthy dietary behaviors may provide bene ts in both CKD and chronic hepatitis. In our study population, the HCV patients were less likely to have healthy dietary behaviors, which could be one possible factor leading to the higher percentage of CKD in this group than the other groups. However, further research is required to identify the composition of dietary interventions for HCV patients with CKD.
The study has several limitations. This was a cross-sectional study without evidence of long-term observations of renal function (eGFR). We were unable to obtain detailed data on viral activity or virus load. Our study participants lived in rural areas with a high prevalence of HCV and had a high mean age, which may result in a higher prevalence of CKD. The study was based on data from a community health promotion program conducted in a local hospital during the daytime. Thus, patients with xed working hours or limited ambulatory ability may not have participated in this program, which could have led to exclusion of more male individuals and more severely ill patients. Moreover, we could not obtain data on the degree of physical activity and exercise, and variation of effect on CKD is unavoidable.

Conclusions
HCV seropositivity, metabolic disturbances, and irregular exercise were signi cantly associated with CKD in this community where viral hepatitis is hyperendemic. Effective viral eradication of HCV and aggressive health promotion of physical activity may help to reduce the occurrence of CKD. The associations between HCV, MetS, and renal dysfunction need to be explored further using long-term studies.

Consent for publication: Not applicable
Availability of data and materials: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Competing interests: The authors declare that they have no competing interests.

Funding: None
Authors' contributions: All authors contributed to statistical analysis and writing of the study. Mei-Yen Chen and Po-Chang Wang participated in study design, acquisition of the data, critical review and wrote the manuscript; Ming-Shyan Lin participated in acquisition of data and designed the research; Chun-Liang Lin, Chang-Min Chung, and Yu-Sheng Lin participated in the analysis and interpretation of data; Yi-Fang Wu collected data and contributed to study direction.