In this community-based study conducted in an area where viral hepatitis is hyperendemic, HCV seropositivity was significantly 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 significantly 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 (22–24); 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 fitness, cardiopulmonary function, and quality of life in patients with CKD (28–30). However, the effects of exercise on eGFR in current studies are conflicting. 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 significantly change eGFR (30–32). 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 stratified by viral seropositivity, and found physical activity may provide additional benefits 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 fibrosis, and soy supplements were related to lower liver inflammation (38, 39). Thus, maintaining healthy dietary behaviors may provide benefits 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 fixed 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.