Appendicitis Rates Linked to Industrialization
December 11, 2015

Appendicitis Rates Linked to Industrialization
by David Wild
Cases of appendicitis appear to surge as countries become more industrialized, and then taper as economies mature, Canadian researchers have found.
What accounts for the correlation is unclear, but experts have suggested everything from poor air quality to improved access to health care as possible explanations.
Pedro Teixeira, MD, a surgeon at the University of Southern California, in Los Angeles, who has researched appendicitis, applauded the study for providing important epidemiologic data. “It could be that the better sanitation and water treatment that accompanies industrialization decreases exposure to intestinal pathogens and consequently alters immune response to infections, increasing the risk for appendicitis,” said Dr. Teixeira, who was not involved in the latest work.
Gilaad Kaplan, MD, MPH, associate professor of medicine at the University of Calgary, Alberta, and his colleagues used Canadian and U.S. administrative databases to document the annual incidence of appendicitis between 2004 and 2008. They also analyzed data from 92 population-based studies from the two countries as well as several other countries.
Dr. Kaplan, who presented the findings at Canadian Digestive Diseases Week 2015 (abstract 70), said his team found that the incidence of appendicitis peaked in the middle of the 20th century, with 383 cases per 100,000 people in North America. In contrast, the average incidence of appendicitis between 2004 and 2008 was 85.8 and 98.1 cases per 100,000 people in Canada and the United States, respectively, he said.
Rates of appendicitis in Europe mirrored North American trends, peaking in the mid-20th century at 601 cases per 100,000 people, Dr. Kaplan’s group reported.
Buttressing the link between industrialization and appendicitis was another of the researchers’ findings, which showed appendicitis rates have been more recently steadily increasing in the Middle East and Asia. Industrialization began later there and is now intensifying.
Dr. Kaplan said air pollution may also have contributed to rising appendicitis rates—a link that has some support.
“My own prior research has found that more air pollution can trigger or exacerbate appendicitis and other autoimmune illnesses, including inflammatory bowel disease,” he said (Environ Health Perspect 2013;121:939-943). “Conversely, as we learned to better manage air pollution over time, in Canada, for example, we saw a coinciding decrease or stabilization of appendicitis rates.”
Yet another explanation for the decreases in appendicitis rates that occurred in the later 20th century and early 21st century is a greater accuracy in the diagnosis of appendicitis, Dr. Teixeira added.
“One plausible explanation is that with improved access to medical care there were possibly higher rates of negative appendectomies, which could have artificially inflated the incidence of appendicitis,” he said. Subsequent improvements in diagnosis would have reduced rates of appendicitis, he said.
A separate but related study presented by Dr. Kaplan’s team at Canadian Digestive Diseases Week (abstract 73) provides an important caveat to the above findings. Namely, his group found that using administrative databases could overestimate incidence rates by up to 15%.

Appendicitis Rates Linked to Industrialization by David Wild Cases of appendicitis appear to surge as countries become more industrialized, and then taper as economies mature, Canadian researchers have found. What accounts for the correlation is unclear, but experts have suggested everything from poor air quality to improved access to health care as possible explanations. Pedro Teixeira, MD, a surgeon at the University of Southern California, in Los Angeles, who has researched appendicitis, applauded the study for providing important epidemiologic data. “It could be that the better sanitation and water treatment that accompanies industrialization decreases exposure to intestinal pathogens and consequently alters immune response to infections, increasing the risk for appendicitis,” said Dr. Teixeira, who was not involved in the latest work. Gilaad Kaplan, MD, MPH, associate professor of medicine at the University of Calgary, Alberta, and his colleagues used Canadian and U.S. administrative databases to document the annual incidence of appendicitis between 2004 and 2008. They also analyzed data from 92 population-based studies from the two countries as well as several other countries. Dr. Kaplan, who presented the findings at Canadian Digestive Diseases Week 2015 (abstract 70), said his team found that the incidence of appendicitis peaked in the middle of the 20th century, with 383 cases per 100,000 people in North America. In contrast, the average incidence of appendicitis between 2004 and 2008 was 85.8 and 98.1 cases per 100,000 people in Canada and the United States, respectively, he said. Rates of appendicitis in Europe mirrored North American trends, peaking in the mid-20th century at 601 cases per 100,000 people, Dr. Kaplan’s group reported. Buttressing the link between industrialization and appendicitis was another of the researchers’ findings, which showed appendicitis rates have been more recently steadily increasing in the Middle East and Asia. Industrialization began later there and is now intensifying. Dr. Kaplan said air pollution may also have contributed to rising appendicitis rates—a link that has some support. “My own prior research has found that more air pollution can trigger or exacerbate appendicitis and other autoimmune illnesses, including inflammatory bowel disease,” he said (Environ Health Perspect 2013;121:939-943). “Conversely, as we learned to better manage air pollution over time, in Canada, for example, we saw a coinciding decrease or stabilization of appendicitis rates.” Yet another explanation for the decreases in appendicitis rates that occurred in the later 20th century and early 21st century is a greater accuracy in the diagnosis of appendicitis, Dr. Teixeira added. “One plausible explanation is that with improved access to medical care there were possibly higher rates of negative appendectomies, which could have artificially inflated the incidence of appendicitis,” he said. Subsequent improvements in diagnosis would have reduced rates of appendicitis, he said. A separate but related study presented by Dr. Kaplan’s team at Canadian Digestive Diseases Week (abstract 73) provides an important caveat to the above findings. Namely, his group found that using administrative databases could overestimate incidence rates by up to 15%.

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