Upper gastrointestinal bleeding secondary to peptic

Upper gastrointestinal bleeding secondary to peptic ulcer disease is a common life-threatening medical condition. However, historically, peptic ulcer disease was an uncommon ailment. The rise in the incidence of peptic ulcer disease occurred in the mid-1800s. At that time, studies in North America and Europe recognised peptic ulcer disease as an important cause of mortality. The incidence of peptic ulcer disease peaked in the latter part of the 19th century and into the early 1900s. However, by the mid-1900s the incidence of peptic ulcer disease began to decrease and subsequently stabilise in regions across the world. The fluctuation in the incidence of peptic ulcer disease over the past two centuries has been retrospectively explained, in part, by the two most common risk factors of peptic ulcer disease: non-steroidal anti-inflammatory drugs (NSAIDs) and . The first NSAID was aspirin, which was introduced in 1899 and contributed to the cause of peptic ulcer disease thereafter. is a bacterium of the stomach that is a major contributor to the incidence of peptic ulcer disease, with some researchers postulating that a virulent strain led to a spike in mortality in the 1800s. However, peptic ulcer disease often manifests in individuals without a history of NSAID exposure and who are not colonised with . Other unknown risk factors of peptic ulcer disease are yet to be discovered. Industrialisation of societies in the 1800s led to urbanisation of populations into cities who often lived in proximity to the factories that polluted the air. The human health impacts of air pollution exposure are well known, with the earliest studies noting its effect on respiratory system. Over the past few decades, several studies have also shown the multi-organ effects of air pollution: breathing air pollution does not limit its effects on health to the lungs. Over the past decade epidemiological studies have documented that air pollution is associated with the development of gastrointestinal diseases such as inflammatory bowel diseases and appendicitis. Basic scientific studies have shown that air pollution might mediate gastrointestinal effects by exacerbating Ranitidine in the intestines and by altering the composition of the intestinal microbiome. Consequently, air pollution could conceivably promote upper gastrointestinal bleeding from peptic ulcer disease by influencing the inflammatory pathways in the stomach or possibly interacting with pathogens of upper gastrointestinal tract such as . My research team led one of the earliest studies to explore this hypothesis. We did a multi-city (Calgary and Edmonton, AB, Canada) time-stratified case crossover study to assess the effects of NO, sulfur dioxide, carbon monoxide, and ozone, as well as particulate matter with aerodynamic diameters of 10 μm or less and 2·5 μm or less. We assessed several models that included different exposure periods, and stratification by age (younger than and older than 70 years), and sex. Although sporadic significant associations were detected, they were not consistent across both cities. Thus, we concluded that these associations were spurious and that a strong signal connecting air pollution exposure with upper gastrointestinal bleeding secondary to peptic ulcer bleeding was not present. However, our negative study does not refute the findings by Tian and colleagues, because important differences between the studies could lead to differential results. Our study populations were distinct, with the majority of individuals in our study being Caucasian in Alberta, and in Tian and colleagues\' study being Asian in Hong Kong. Additionally, exposure to air pollution is different between cities. For example, the average daily concentration of NO in Alberta was 23·9 μg/m, whereas the average daily concentration in Hong Kong was nearly double at 55·7 μg/m. A threshold level of NO may be necessary to trigger a health event such as bleeding from an ulcer. These differences highlight the need to assess the health effects of air pollution in different regions and study populations. So could air pollution be a novel risk factor for upper gastrointestinal bleeding secondary to peptic ulcer disease in Asian populations? Although it is an intriguing hypothesis, we must consider important limitations of air pollution research.