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Trend analysis and prediction of the incidence and mortality of CKD in China and the US – BMC Nephrology

In this study, CKD incidence in China and the US is found to be increasing annually; the mortality rate of CKD in China is decreasing, and the mortality rate of CKD in the US is increasing. The RR of CKD incidence and mortality increased gradually with age in general; however, people aged < 5 years had a higher RR of CKD incidence than those in the other age categories. The RR of CKD incidence increased gradually over time, and the RR of CKD mortality in the US increased gradually as well. Later years of birth were associated with lower RRs of CKD incidence and mortality, and it is predicted that CKD incidence will increase, but the mortality rate will decline over the next 15 years.

Many factors affect the development of CKD, including age, sex, obesity, hypertension, diabetes mellitus, and hyperuricemia. The kidney is one of the target organs of obesity-related health disorders, a risk factor for CKD progression, and obesity is considered to be an independent risk factor for CKD development [18]. Studies have shown a U-shaped correlation between body mass index and renal function decline [19]. Diabetes is the most common cause of CKD worldwide. In the supplementary materials, a consistent upward trend in the ASIR of diabetes is observed in both China and the US, with the ASIR being consistently higher in the US. Additionally, the ASIR of CKD attributed to type 2 diabetes exhibits a comparable increasing trend in both countries, with the ASIR in the US exceeding that in China. These findings are consistent with the overarching results of the study, further substantiating the robust correlation between diabetes and CKD incidence. Compared to other causes of CKD, patients with CKD and diabetes are at a higher risk of developing end-stage renal disease (ESRD), which imposes a huge health and economic burden on both patients and society [20]. Hypertension is also a risk factor for CKD. Studies have shown that a systolic blood pressure (SBP) of 140 mmHg is associated with an increased risk of CKD incidence [21]. A decrease in SBP can significantly reduce mortality in patients with mild-to-moderate CKD and hypertension [22]. Studies have also shown that elevated serum uric acid is a risk factor for the development of both acute and chronic kidney diseases, as well as hypertension and diabetes. Uric acid may cause kidney disease by causing systemic and glomerular hypertension [23]. This study discovered that individuals aged 0–5 have an elevated RR of CKD incidence, with CKD in children resulting in significant height development and disproportionate growth disorders. Research has suggested that factors like hyperglycemia, vitamin A deficiency, and exposure to cocaine and alcohol during pregnancy can heighten the RR of CKD in infants [24]. Moreover, low birth weight and premature birth are also linked to an increased RR of CKD in infants [25]. The immature liver and kidney functions in children demand stringent dietary safety standards. Unhealthy dietary choices, such as inappropriate infant formula and adult food not suited for children, may harm their health, potentially leading to CKD. A notable example is China’s outbreak of pediatric urolithiasis due to melamine-contaminated milk powder. The Chinese Ministry of Health reported that approximately 294,000 children were diagnosed with urinary tract stones [26]. Studies have indicated that melamine-associated urolithiasis can cause damage to renal tubules and glomeruli [27]. This factor may contribute to the marginally higher RR of CKD among Chinese children aged 0–5 compared to their counterparts in the US.

The ASIR of CKD was found to increase in China and the US, and the period effect in the age-period-cohort analysis of CKD incidence also suggested that the RR of CKD incidence increased annually. With societal development over time, the aging of the population, and improvements to living standards, the risk factors for CKD also increase, and the incidence and risk of CKD also increase. In the 1990s, China’s economic level rose rapidly due to the implementation of the Economic Reform and Open Up approaches; the ASIR of the CKD changed from a downward trend to an upward one. The ASIR of CKD in the US decreased from 2005 to 2010, which may be attributed to the rapid growth in GDP and the improvement of health services in the US during this period. The ASIR for CKD was found to be higher in the US than in China. Research shows that in the US, 1/3 of the total population is obese, and another 1/3 is overweight. The obesity rate in the US is higher than that in China [18]. According to GBD data, the incidence of diabetes and hypertension in the US is higher than that in China, which may explain why the incidence of CKD in the US is higher.

Joinpoint Regression analysis suggested that the ASMR of CKD in China decreased, whereas that in the US increased. The period effect in the age-period-cohort analysis of CKD mortality suggested that the RR of CKD mortality in the US increased each year. In terms of age, the RR for CKD incidence and mortality in the US were higher than those in China. This may be because the Chinese government, which established the China Kidney Network (CK-NET) in 2014 [18], has continuously strengthened the reform of the medical system to ensure fairness of medical services for the masses, providing data to support the formulation of health policies. Other studies have pointed out that patients with CKD comprise a high proportion of African Americans and other ethnic and socially disadvantaged groups in the US, which also reflects the inequality of health service access and unfair health policy in the US [18]. This may explain the increased CKD mortality and higher RR of CKD mortality in the US.

The ASIR of CKD was found to be higher in women than in men, and the ASMR of CKD was higher in men than in women. The reason behind this difference remains unclear. It may be due to the fact that women generally have less muscle mass than men, and muscle mass is the main determinant of serum creatinine concentration, thus making CKD more detectable in women [28, 29]. Studies have shown that sex-based differences in systemic and renal hemodynamics and hypertension control, as well as differences in the effects of sex hormones on cell metabolism, lead to the slower progression of CKD in women than in men [6, 30]. This may explain why CKD mortality is higher in men than in women.

The cohort effect in our age-period-cohort analysis suggested that the RR of CKD incidence and mortality decreased with cohort size, which may be the result of the development of medical technologies over time. However, the RR of CKD mortality in Chinese people born between 1910 and 1949 is on the rise, which may be because China is in a period of war and turmoil, and the medical services of the population are not guaranteed, leading to an increase in the RR of mortality.

Our prediction shows that the incidence of CKD in China and the US will increase, and mortality will decline over the next 15 years. To enhance the prevention and treatment of CKD, both countries should proactively implement relevant health policies, particularly focusing on increasing healthcare accessibility in the US. This includes screening for high-risk CKD populations, notably those with hypertension and diabetes. CKD screening effectively delays CKD progression and reduces cardiovascular disease risk [31]. It is advisable to regularly monitor kidney function, urinary protein, blood pressure, and other indicators for early CKD detection and intervention. For patients with end-stage renal disease (ESRD), increasing access to dialysis and kidney transplantation is crucial to enhance their quality of life and prognosis. Given the higher obesity rate in the US compared to China, American residents need to adhere to a healthy diet to decrease obesity incidence, thereby reducing the risk of developing CKD. Regular physical activity and healthy eating habits are also important. Research has shown that adherence to a diet rich in whole grains, vegetables, fruits, beans, nuts, and fish, as well as reducing the intake of red meat and processed meat, sodium, and sugary drinks, are related to a lower RR of CKD incidence [32]. Physical exercise can effectively prevent the occurrence of CKD and improve both the quality of life and the blood pressure levels of patients with CKD [33].

The limitations of this study include potential inaccuracies in the GBD database data: while extensive, the data in GBD are prone to significant errors and rely heavily on estimations, potentially impacting the research findings. Additionally, as this study is ecological in nature, ecological fallacy cannot be avoided, with variations in population distribution and age differences possibly influencing the results. In this study, statistical models and years were employed to estimate the age-standardized incidence or mortality rates, yet the influences of economic, cultural, and health development levels, demographic shifts, or policy interventions on these rates were not considered. Furthermore, due to the absence of detailed data on the incidence and mortality of different CKD stages in the GBD database, this study is unable to provide an analysis of CKD at various stages.