The estimated prevalence of 1.32 million foreign-born (FB) persons with CHB in the United States reported in this study is higher than previous estimates because the study attempted to reduce the underestimation of CHB prevalence among FB persons in the United States.
While persons from Africa and Asia have the highest prevalence rates, FB immigrants from Central America and Caribbean may account for a significant number of CHB cases due to their large populations in the United States.
Results of this study emphasize the need to improve and expand screening of FB individuals using HBsAg testing.
PLEASE NOTE: Each article is selected by faculty on the scientific merits of the new data. It is one part of a bundled series of articles that, as a group, provide a full and balanced perspective.
Chronic hepatitis B (CHB) affects an estimated 350 to 400 million persons worldwide, constituting a major global health problem. About 15% to 25% of individuals with CHB are at risk for premature death due to clinical complications such as hepatocellular carcinoma and end-stage liver disease. Previous estimates of the total number of individuals with CHB in the United States ranged from 550,000 to 2 million, with foreign-born (FB) accounting for 40% to 70% of the cases. However, since FB and other high-risk individuals have typically been under-represented in past studies, it has been suggested that these figures underestimate the prevalence of CHB in the FB persons. With the increasing FB population in the United States, many of whom emigrate from areas with high CHB endemicity, such as Asia and Africa, more accurate estimates of the CHB prevalence among FB persons are needed.
In an effort to gain a more realistic assessment of the prevalence of CHB among FB individuals living in the United States, Kowdley et al conducted a systematic review of 1,373 articles reporting hepatitis B surface antigen g (HBsAg) seroprevalence rates in102 countries, which included 256 seroprevalence surveys in those migrating to the United States from 52 countries (n = 689,078) and 1,797 surveys in the general population of 98 countries of origin (n = 17,861,035)1. Country-specific pooled CHB prevalence rates were generated by meta-analyses of combined data. These rates were multiplied by the number of FB in the United States in 2009 by country of origin from the US Census Bureau to generate the number of FB with CHB.
The highest pooled average CHB prevalence rates were found for FB persons from Africa (10.3%), Asia (7.27%), Oceania (4.78%), and Caribbean (4.52%).The average CHB prevalence rate for all FB persons in the United States was 3.45%. Country-specific CHB prevalence rates in Africa were highest for Sudan (18.59%), Liberia (16.54%), Guinea (16.33%), and Eritrea (15.52%); in Asia for Laos (13.61%), Yemen (13.23%),Vietnam (12.48%), and China (12.25%); in Oceania for Micronesia (15.11%); and in the Caribbean for the Dominican Republic (10.68%). Approximately 52%, 37%, and 11% of the FB persons originated from countries with high (rates ≥ 8%), intermediate (2%–7.9%), and low (<2%) hepatitis B endemicity, respectively.
The study found that the estimated number of FB with CHB in the United States was 1.32 million. Of those, 58% (773,397) migrated from Asia, 11.7% (155,852) from Caribbean, 11% (152,054) from Africa, 7.4% (97,995) from Europe, and 7% (96,489) from Central America. Countries with the largest numbers of FB with CHB in the United States were China (243,484), Vietnam (143,440), Philippines (127,612), Dominican Republic (84,542), and Mexico (56,243).
Earlier estimates of the number of FB with CHB in the United States ranged from 317,000 in one study to 375,000 to 975,000 in a second study. The difference between the estimated 1.32 million FB with CHB reported in this study compared to previous reports is due to the higher CHB rate (3.45%). The approach used in this study to include both FB populations living in the United States and in-country populations in their countries of origin was an attempt to correct for underrepresentation of CHB in previous studies among the FB, which excluded undocumented persons and those at high-risk for CHB (such as incarcerated and institutionalized persons) and likely resulted in the higher CHB prevalence rates that may better represent the true CHB rates among various FB populations in the United States.
This was a large study that included surveys of FB in the United States and in-country populations in the nations from which they migrated. Although in-country surveys may not be as representative of the CHB prevalence rates of FB in the United States as surveys in FB individuals, the seroprevalence rates were not significantly different between the two groups in 35 (71%) of the 49 countries for which both population data were available. In addition, heterogeneity among surveys was assessed by comparing the results of random effect (RE) and fixed effect (FE) analyses for each country. Except for China, in which the FE prevalence rate was slightly higher than the RE rate (13.3% versus 12.3%), the FE rate was similar or lower than the RE rate for most countries.
In conclusion, the prevalence of CHB in FB persons living in the United States appears to be much higher than previously reported and will continue to rise with ongoing immigration of people from countries with intermediate and high CHB prevalence rates. While the highest prevalence rates of CHB are found among FB persons from Africa and Asia, FB people from Central America and Caribbean account for a large number of cases. Although the CHB prevalence rates are relatively low in these areas, because of the large number of FB in the United States from these regions, they contribute significantly to the overall prevalence. This study emphasizes the need for primary care physicians and general internists to improve and expand screening and HBsAg serologic testing of FB individuals at-risk for CHB, so that early monitoring and treatment can be instituted.
1. Kowdley KV, Wang CC, Welch S, Roberts H, Brosgart CL. Prevalence of chronic hepatitis B among foreign-born persons living in the United States by country of origin. Hepatology. 2011; Nov 22 [Epub ahead of print]