GI Epidemiology

Diseases and Clinical Methodology

Nicholas J. Talley, G. Richard Locke, Paul Moayyedi, Joseph J. West, Alexander C. Ford, Yuri A. Saito, Nicholas J. Talley, G. Richard Locke, Paul Moayyedi, Joseph J. West, Alexander C. Ford, Yuri A. Saito

• Publisher: Wiley-Blackwell
• Year: 2013
• ISBN:
  9781118727096
• Edition: 2
• Topic: Medicine
• Subtopic: Gastroenterology & Hepatology

Identifying how, why and in whom gastrointestinal disease occurs, and what can be done to prevent it, is of key importance for the modern-day gastroenterologist and researcher.

Brought to you by the world's leading gastroenterologists, the second edition of GI Epidemiology: Diseases and Clinical Methodology is the only book that combines detailed analysis of the epidemiology of GI disease with a study of the methodology of clinical research.

With a much greater clinical focus on the diagnostic and management approach for each disease than
before, all existing chapters are fully updated with the very latest in statistical and clinical data. In addition, the revised edition contains several significant improvements, notably:

• Five extra disease epidemiology chapters: Upper GI Bleeding; Hepatitis B and C; Common Tropical GI
Diseases; Nutritional Epidemiology and GI Cancers; and Obesity among Adults

• More illustrations, including maps of each disease

• A more international focus with the inclusion of two experienced European editors

• MCQs, summary checklists and key points throughout

• Ten extra online-only chapters on methodological issues related to GI epidemiology such as Patient reported

GI Epidemiology: Diseases and Clinical Methodology, 2nd Edition is the perfect reference tool for gastroenterologists involved in both patient management and clinical research, and also for epidemiologists involved specifically in GI disease data and more general epidemiological studies.

Titles of Related Interest

Yamada's Handbook of Gastroenterology, 3rd Edition
Yamada; ISBN 9780470656204

Essentials of Gastroenterology
Friedman; ISBN 9780470656259

PART ONE

Gastrointestinal Diseases and Disorders: The Public Health Perspective

1

The burden of gastrointestinal and liver disease around the world

Hannah P. Kim1, Seth D. Crockett2, & Nicholas J. Shaheen3

1Division of Gastroenterology and Hepatology, University of North Carolina School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

2Division of Gastroenterology, University of North Carolina School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

3Center for Esophageal Diseases and Swallowing, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA

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Key points

• Gastrointestinal and liver diseases are among the most common diseases worldwide, with diarrheal disease, malignancies, and liver disease having a substantial toll on worldwide mortality.
• Many of these diseases are preventable and possibly curable.
• There is wide variability in the incidence, management, and mortality associated with these disease states throughout the world.
• Understanding trends in GI illness and the factors responsible for variability in incidence and outcomes will allow clinicians, public health professionals, policy makers, and healthcare organizations to intervene in a more logical way and allocate resources to meet the needs of afflicted patients and decrease the burden of gastrointestinal and liver diseases.

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Introduction

Gastrointestinal and liver diseases represent a significant global health problem, and cause approximately 8 million deaths per year worldwide [1]. In developed countries, GI malignancies are among the leading causes of death. In developing countries, diarrheal disease and viral liver infections are highly prevalent and are responsible for significant mortality. These and other diseases are tracked by international and regional health organizations. These tracking measures allow for some assessment of the global burden of GI disease, and may allow identification of important temporal trends.

Below we highlight sources of burden of GI illness internationally. Using international databases, we will highlight some important trends in diarrheal disease and childhood mortality, explore the burden of gastrointestinal malignancies, and discuss the toll of several selected liver diseases. Because valid international estimates are not available for some gastrointestinal conditions, we report regional data with respect to the toll of other selected GI diseases.

Much of the data demonstrated below has been collected as part of various projects conducted by the World Health Organization (WHO). Geographical regions that are discussed throughout this chapter are based on the six officially delineated WHO regions: Africa, the Americas, Eastern Mediterranean, Europe, Southeast Asia, and Western Pacific. A map delineating each region can be found at: http://www.who.int/about/regions/en/index.html.

Diarrheal disease

Global burden

An estimated 2.5 billion cases of diarrhea occur annually in children under five years of age [2], with an estimated frequency of 2–3 episodes per child per year in developing countries [3]. Diarrheal disease is the second leading cause of mortality in this age group worldwide, after pneumonia. Responsible for over 15 % of deaths of children less than five years of age, diarrheal disease accounts for more than 1.3 million deaths each year. It is also responsible for more deaths than HIV/AIDS, malaria, and measles combined [1].

Figure 1.1 displays the number of under-5 deaths secondary to diarrheal disease by WHO region. Diarrheal death is much more common in the developing world, with over 56 % of deaths occurring in Africa. Africa and Southeast Asia combined account for nearly 80 % of all under-5 diarrhea-related deaths. Furthermore, 75 % of childhood deaths attributable to diarrheal disease can be found in just 14 developing countries, led by India, Nigeria, and the Democratic Republic of the Congo [4]. This is largely due to contamination of drinking water and compromised sanitation in these countries. Children in these countries develop nutritional deficiencies, and are more susceptible to repeated episodes of diarrhea and severe dehydration, also contributing to the high incidence of mortality due to diarrhea in developing nations [2].

Figure 1.1 Deaths secondary to diarrheal disease among children aged <5 years by WHO region, 2008. Source: WHO Health statistics and health information systems – child mortality by cause.

Efforts to reduce the number of childhood deaths secondary to diarrheal disease in the 1970s and 1980s have favorably impacted the burden of diarrheal disease. These efforts included increasing oral rehydration therapy and the implementation of programs to educate caregivers on proper treatment. While the overall incidence rates of diarrheal disease have remained stable throughout the past three decades, there has been a decrease in diarrhea-associated deaths [3]. Estimates have shown a steady decline with 4.6 million deaths per year in the 1960s and 1970s, 3.3 million deaths per year in the 1980s, 2.5 million deaths per year in the 1990s, and 1.5 million deaths in 2004 [2, 5,6,7]. Despite this improvement, diarrhea continues to be an unacceptably common cause of childhood death, especially in developing countries.

Gastrointestinal malignancies

Global burden

Cancer is the leading cause of death in developed nations and is the second leading cause of death in developing nations [8]. GLOBOCAN is a WHO project which estimates the international burden of cancer using population-based cancer registries [9]. Gastrointestinal cancers were responsible for nearly one-third of new cancer cases in 2008. Table 1.1 displays incidence of, and mortality from, gastrointestinal cancers worldwide, as well as their rank among all major cancer sites. Colorectal cancer continues to have the highest incidence rate among gastrointestinal malignancies and is the third most commonly occurring cancer worldwide, with over 1.2 million new cases estimated in 2008. Hepatocellular, esophageal, and pancreatic cancers are of particular importance because of their high mortality; in fact, mortality-to-incidence ratios approach one internationally. Colorectal cancer is associated with a much better prognosis, with a mortality-to-incidence ratio of approximately 0.5. Assessment of the three most commonly occurring gastrointestinal malignancies worldwide demonstrates marked variation in incidence and mortality. Colorectal and gastric cancers will be discussed in the following two sections and liver cancer will be discussed in a later section.

Table 1.1 Incidence and mortality of gastrointestinal cancers worldwide, 2008

Colorectal cancer

Colorectal cancer is the third highest incident cancer, and fourth most common cause of death from cancer worldwide, with over 609,000 deaths estimated in 2008. Approximately 60 % of colorectal cancer cases are found in developed regions; however, only approximately 53 % of deaths attributable to colorectal cancer are found in these same regions. Of note, the incidence rate of colorectal cancer in Africa is a small fraction of that in Europe, but is associated with cancer-related mortality in nearly all cases.

In the last three decades, the United States has witnessed a decrease in the incidence rate of colorectal cancer and an even greater decrease in the mortality rate. The extent to which decreasing colorectal cancer mortality can be attributed to earlier detection of colorectal cancer and improved methods of treatment is debated [10]. Unfortunately, those in less developed regions, where proper resources are lacking, suffer poorer prognoses.

Gastric cancer

Gastric cancer is the second most common gastrointestinal cancer and the fourth most common cancer worldwide. It was responsible for nearly 1 million new cancer cases and approximately 737,000 cancer deaths in 2008, making it the number one GI-related cancer killer worldwide. More than 70 % of the new cases and more than 75 % of deaths occurred in less developed regions. The incidence rate of gastric cancer is greatest in the Western Pacific, with nearly half of all cases being found in China (463,000 cases) and with highest incidence rates among the Republic of Korea and Japan. The lowest rates of gastric cancer can be found in Africa, Southeast Asia, and the Eastern Mediterranean regions. Regional variation may be partially attributed to differences in dietary patterns and the prevalence of Helicobacter pylori infection [8]. While gastric cancer is one of the leading causes of cancer death, individuals with gastric cancer in the Western Pacific tend to have better prognoses than those in other regions, possibly due to the increased use of screening methods and earlier detection of cancer [11].

Selected diseases of the liver

Hepatitis B

An estimated 2 billion people worldwide have been infected with the hepatitis B virus (HBV). More than 350 million people have chronic liver infections, and approximately 600,000 persons die annually due to acute or chronic consequences of the virus. Hepatitis B is estimated to be the cause of 30 % of cirrhosis and 53 % of hepatocellular carcinoma [12]. Hepatitis B is endemic in China and other parts of Asia, with most infections occurring during childhood, and 8–10 % of the adult population being chronically infected. In contrast, less than 1 % of the population in Western Europe and North America is chronically infected [13].

In developing countries, HBV is largely transmitted during childbirth and early childhood infections. In developed countries, transmission is primarily through high-risk sexual behavior and IV drug use, as well as from migration of infected individuals from high prevalence areas [14]. Those infected at a young age are most likely to develop chronic...