The worldwide prevalence of liver cirrhosis continues increase with poor prognosis [10]. The heterogeneous pattern in risk factors causes the prevalence of liver cirrhosis to be different and makes the development of prevention policies complex [11, 12]. Although the incidence of HBV and HCV continuously decreases, the ever-increasing incidence of liver cirrhosis caused by alcohol and NASH remains a formidable threaten [13, 14].
In our study, we analyzed the trends in liver cirrhosis. In general, the prevalence of liver cirrhosis continuously increased. The trends were mainly dominated by an increase in NASH-induced liver cirrhosis, with a smaller contribution from alcohol use. In contrast, the prevalence of HBV and HCV increased during the period, but the ASR decreased [15]. The decreasing trends were mainly caused by the decrease in the number of patients with HBV- and HCV-related liver cirrhosis [16, 17]. In contrast to our view that hepatitis is the main cause of liver cirrhosis, liver cirrhosis caused by NASH occupied a major position in the prevalent cases [15]. Consequently, exploring the exact pattern of liver cirrhosis etiologies is important for developing specific preventive measures. In our study, the HDI and EAPC were found to be positively correlated. HDI was a summary measure indicative of a long and healthy life, being knowledgeable and having a decent standard of living. The HDI simplified and captured only part of human development details. Moreover, patients with liver cirrhosis had a long survival time. With the increase in the life expectancy index, the prevalence of patients with liver cirrhosis also increased. Thus, the dimensions of HDI might be positively correlated with EAPC. Moreover, a study conducted by Liu et al also indicated that the HDI and EAPC were positively correlated in patients with liver cancer [1]. In 1990 and 2017, 46% and 59% of liver cirrhosis patients, respectively, had NASH. The highest ASR increase in prevalent cases was also found in patients with NASH, which was different from the results found in other studies [1, 18]. Additionally, in contrast to other studies that used incidence as an indicator, we used prevalence as the indicator. Because patients with liver cirrhosis had a long survival time, it was more reasonable to use prevalence as the indicator. We further analyzed the reason why NASH accounts for the highest proportion in prevalent cases. We found that liver cirrhosis caused by hepatitis accounted for the highest proportion of deaths by analyzing the GBD data, while liver cirrhosis caused by NASH accounted for the lowest proportion of deaths. Therefore, more and more patients had cirrhosis caused by NASH over time, but fewer patients died, resulting in a higher proportion of prevalent cases. A study revealed that the annual percentage change of mortality of NASH-induced cirrhosis was 3-fold greater than that for alcohol-induced cirrhosis, and NASH surpassed alcohol and hepatitis to be the leading cause of liver cirrhosis in the United States [19]. This might be related to the obesity epidemic in the United States, and the burden of NASH-induced liver cirrhosis might increase over the next decade [20]. Thus, public policy, which focused on primary prevention, prompt diagnosis, and pre-emptive therapy should establish plans to raise awareness and decrease the disease burden of NASH.
HBV was an important risk factor for liver cirrhosis in some regions [21, 22]. Moreover, HBV infection contributed to half of the mortality associated with liver cancer [23]. In our study, we found that liver cirrhosis caused by HBV was more prevalent in the low-middle and middle SDI regions. Additionally, more than 50% of patients with liver cirrhosis in Africa were caused by HBV, and nearly 40% of the cases in East Asia, Central Asia and Oceania were also caused by HBV. By promoting HBV vaccination, the ASR of the 21 regions decreased over the last few decades. Although China had the largest number of HBV patients, the growth rate was only 10.21% from 1990 to 2017. This was mainly due to the promotion of HBV vaccines in China [24]. By implementing these measures, the number of patients suffering from HBV infection was significantly suppressed in the general population [25, 26]. Amazingly, although the ASR decreased during the period in all 5 SDI regions, the smallest decrease was found in high the SDI regions, such as North America–high income and South Asia. This finding indicates that more effective public measures to prevent HBV should be implemented in these countries [27]. Moreover, the development of anti-HBV drugs, such as entecavir and tenofovir, has further reduced the number of patients [28]. Thus, we can expect that the number of patients with liver cirrhosis caused by HBV will be significantly decreased in the future.
Similar to liver cirrhosis caused by HBV, the ASR of liver cirrhosis caused by HCV also decreased. Additionally, the ASR of liver cirrhosis caused by HCV also decreased in all 5 SDI regions. To our surprise, the ASR increased in Eastern Europe, Tropical Latin America and North America–high income, which was not the same as the results reported in the study conducted by The Polaris Observatory HCV Collaborators [29]. China also had the largest number of patients with HCV, but the growth rate was 34.01% [30]. This might be related to a lack of effective treatment measures before 2014. Subsequently, direct-acting antiviral therapy was introduced, and more than 90% of patients with all genotypes of HCV could be cured [31]. As a result, interventions should be introduced all over the world, such as promoting direct-acting antiviral therapy and reducing the therapy price.
Alcohol was proven to be a major risk factor for liver cirrhosis. The ASR of liver cirrhosis caused by alcohol use increased from 1990 to 2017. The results obtained by Asrani et al also revealed that alcohol use and NASH have overtaken hepatitis as the primary causes of liver diseases in Western countries [32]. The increase in ASR was higher in females than in males, similar to the result obtained by Roerecke et al [33]. Additionally, alcohol was found to play an increasingly important role in chronic liver diseases [34]. Thus, polices to reduce alcohol consumption should be implemented to improve population health, and people with high alcohol consumption should receive interventions to reduce their intake [33].
Although the GBD data demonstrated the temporal trend in the prevalence of liver cirrhosis, several limitations should be noted. The accuracy of results obtained from GBD data depend on the quality and quantity of liver cirrhosis data. In some countries or regions, the liver cirrhosis data were incomplete or even missing. This may have led to an underestimation of the severity of liver cirrhosis. Additionally, we could only study the temporal trend in the prevalence of liver cirrhosis by each etiology, and the interaction between etiologies could not be studied via the GBD data.
In summary, liver cirrhosis poses a huge threat to people's health. Although the ASR of liver cirrhosis caused by hepatitis decreased with HBV vaccination and direct-acting antiviral therapy, the ASR of liver cirrhosis caused by alcohol and NASH continued to grow during the study period. Thus, public health priorities that target alcohol consumption and NASH should be implemented as soon as possible.