Duodenal ulcer--does it exist in Australia aborigines?

A collection of the etiological theories, characteristics, and observations/phenomena of peptic ulcers in existing data

In this article, we compiled 13 etiological theories, 15 characteristics, and 81 observations/phenomena of peptic ulcers, reported in reproducible, peer-reviewed studies from the literature, to reflect the historical evolution of studies on peptic ulcers and to provide a multidisciplinary view of this disease. This data was collected during the systematic review of topics on peptic ulcers including genetics, etiology, epidemiology, psychology, anatomy, neurology, bacteriology, pathology, and clinical statistics. The data curated herein was extracted via application of recently published basic theories and methodologies.

Differences in peptic ulcer between East and West

In general, peptic ulcer occurs at equal rates in the East and the West but with marked regional differences in both, even within the same country. In the West, the incidence of peptic ulcer, particularly duodenal ulcer, rose sharply at the turn of the century and has shown a rapid decline in the past three decades. In the East, the rise was equally impressive, but the decline appears to have been delayed, only starting in the past decade. Asians present their ulcer symptoms a decade earlier than Caucasians, and it has been suggested that this early presentation may be attributable to Helicobacter pylori (H. pylori) infection at a younger age. Interestingly, the male-to-female ratio is much higher in the East than in the West, and the duodenal-to-gastric ulcer ratio manifests a much wider variation in Asians than in Caucasians. As in Western countries, peptic ulcer occurrence in the East shows a cyclical trend, with a peak frequency in the winter months. In the West, the placebo healing rate varies widely up to 78%, whereas in the East it is rather consistent at around one-third. These variations in geographical distribution, time trends, sex and ulcer ratios, seasonal rates and behavioral response to placebo treatment indicate that while H. pylori is a major cause of peptic ulceration, other environmental and genetic factors contribute to ulcer formation. The parietal cell mass and acid secretory capacity of Asian patients with duodenal ulcer are only slightly more than half of those of Caucasian patients, which may explain why Asian patients respond equally well to half the standard dose of anti-secretory agents used in Caucasians. H. pylori infection is generally more prevalent in the East than in the West and is more resistant to metronidazole. The response to standard triple therapies for eradication, however, appears to be as effective in the East as in the West.

Helicobacter pylori in duodenal and gastric ulcer disease

The decision to treat a patient should in general always be based on potential risk and advantage. Widespread and uncontrolled use of all kinds of anti-H. pylori regimens may promote development of antimicrobial resistant strains. In particular, antimicrobial monotherapy is associated with failure to eradicate H. pylori and induction of resistant strains. Polychemotherapy is much more effective and has a lower risk for development of antimicrobial resistant H. pylori strains but carries the risk of significant drug-related side effects. If the prescribed anti-H. pylori regimen is not effective in at least 80%, or if the patient is not compliant, this type of therapy should not be considered. Also if reinfection is to be expected, the risk may outweigh potential benefits (Graham, 1993). Guidelines published in 1990 by an international working party during the World Congress of Gastroenterology recommended H. pylori eradication only in patients where duodenal ulcer was a serious management problem requiring lifelong maintenance therapy, and in whom complications (bleeding, perforation) had occurred or surgery was considered (Tytgat et al, 1990). Recently less stringent guidelines were recommended. A National Institutes of Health (NIH) Consensus Development Conference has recommended that all patients with gastric or duodenal ulcer who are H. pylori infected should be treated with antimicrobials including patients presenting with an ulcer for the first time. In addition, patients on maintenance antisecretory medication should also be contacted and treated for H. pylori infection (Anonymous, 1994). The ulcer relapse rate during prolonged follow-up after H. pylori eradication is very low. Despite this, it is advised that antisecretory medication is continued after successful H. pylori eradication in patients with previous ulcer complications. In all other patients maintenance antisecretory medication can be stopped after successful eradication. It is not known whether H. pylori eradication lowers the risk of NSAID-induced ulceration or whether the risk of ulcer complications is reduced.

Aetiological factors of peptic ulcer: perspectives of epidemiological observations this century

There are five known environmental, causative factors for peptic ulcer, namely, non-steroidal anti-inflammatory drugs (NSAID), Helicobacter pylori infection, cigarette smoking, environmental stress and dietary habit. There have been six factual, epidemiological observations on peptic ulcer this century: the rise and fall of ulcer frequency in Western societies; geographical variations in ulcer rates; in sex ratios; in duodenal: gastric ulcer ratios; and in placebo healing rates; and seasonal variation in ulcer frequencies. This report examines each of these epidemiological observations to see if each of the environmental factors can explain the observations. The secular trends and the variation in ulcer rates can be related to all the environmental factors. The sex ratios can be explained on the basis of cigarette smoking and environmental stress, whereas the duodenal: gastric ulcer ratios may be ascribed to NSAID use. Placebo healing and seasonal occurrence of ulcer is probably more related to environmental stress. Helicobacter pylori infection alone cannot explain the sex ratios, the duodenal: gastric ulcer ratios, the placebo healing and the seasonal occurrence of ulcer. Cigarette smoking or NSAID use alone does not tally with the seasonal variation of ulcer frequencies. Environmental stress alone does not fit into the recent fall of ulcer rates in Western countries. This report supports the concept of heterogeneity in peptic ulceration.

Epidemiology and genetics of peptic ulcer

At the turn of the century, duodenal ulcer rose from rarity to affect 10% of males in their life time, subsequently declining in some countries such as UK, levelling off in others such as Germany, and continuing to increase in still others such as Hong Kong. The annual incidence per 1000 population varies from about 1 in Japan to 1.5 in Norway, 1.8 in USA and 2.7 in Scotland, and the frequency also varies within many individual countries, such as Australia, China and India, and among races such as a higher prevalence among whites than blacks in USA and among Chinese than Javanese in Indonesia. Ulcer frequency is higher in winter months, and this appears universal, being true in cold as well as in warm countries. Most places report a rise of ulcer rates among the elderly in recent decades. The male to female ratio also varies geographically, for example from 1:1 in USA to 18:1 in India, and with time such as moving from 2:1 to 1:1 in the last two decades in USA, and the duodenal ulcer to gastric ulcer ratio varies widely from place to place, for example from 0.8 in Japan to 19:1 in Africa and 32:1 in India. Placebo healing rates also differ geographically, ranging from 5% in Philippines to 78% in Mexico. These epidemiological data can only be explained by the presence of multiple aetiological factors, including analgesics, society stress, cigarette smoking, Helicobacter pylori, dietary factors, and genetic factors. Three lines of evidence support a genetic role: family studies, twin studies and blood group studies. Family aggregation occurs more commonly in patients with early-onset (< 30 yr) of symptoms. Blood group O prevalence is more associated with late-onset of symptoms. Other genetic markers include nonsecretor status, HLA antigens, phenylthiocarbamide taste sensitivity, and alpha-1-antitrypsin. Genetic syndromes such as MEN I also support a genetic role and give insight into pathogenetic mechanisms. The best physiological marker is still hyperpepsinogenemia I, which is transmitted by autosomal dominance, despite recent report of lower serum pepsinogen 1 after healing of Helicobacter pylori associated gastritis.

Seroepidemiology of Campylobacter pylori infection in various populations

Campylobacter pylori infection has been recognized as being strongly associated with chronic gastritis and duodenal ulceration, but the prevalence of C. pylori infection in a normal population is not known. A serological survey was conducted in four countries with different geographical and socioeconomic status, in a randomly chosen population as representative as possible, by using an enzyme-linked immunosorbent assay (ELISA) with a sonic extract of two strains as the antigen. The test had a specificity of 94% when 600 ELISA units was used as the threshold. In France, few children were infected before the age of 10 years. The prevalence then increased gradually to 36.7% in the sixth decade of life. This increasing prevalence of infection with age was also observed in Algeria, Vietnam, and the Ivory Coast but at a higher rate (80 to 90%). In Vietnam, as in France, few children were infected, whereas in Africa, C. pylori infection occurred earlier. The prevalence of infection did not differ with sex for a particular age group; it also did not differ with respect to gastric symptoms, smoking and drinking habits, or urban or rural residence when these potential risk factors were studied. The epidemiological data available on peptic ulcer disease in developing countries compared with developed countries led to the speculation that infection with C. pylori is not a sufficient condition to develop this disease.

Antibody response to Campylobacter pylori in an ethnic group lacking peptic ulceration

The association between duodenal ulcer, gastritis and gastroduodenal colonization with Campylobacter pylori suggests a causal role for this newly described bacterium. In an attempt to challenge the verity of this association we studied a group of people in whom duodenal ulcer is apparently absent. Serological evidence of infection was sought with a sensitive, specific ELISA assay for C. pylori specific IgG and was compared with results from control sera from teenagers referred for respiratory viral serology, volunteer blood bank donors, patients with duodenal ulcers and patients in whom the presence or absence of C. pylori had been determined by histological and microbiological examination of gastric tissue. A relatively isolated group of Australian Aborigines in whom peptic ulceration is virtually unknown, was observed to possess age-specific mean C. pylori antibody levels comparable those found in a group of white Australian dyspeptic patients without microbiological evidence of infection with this organism. The antibody levels of Aborigines were lower than those found in an aged-matched group of 'healthy' white Australians, both of these groups having levels which were significantly lower than the levels found in culture positive white Australian dyspeptic patients. It was found that 21/144 'healthy' white Australians (14.6%) had antibody levels greater than or equal to the lower 99% confidence interval of the mean level found in culture positive patients, while only 2/274 Aborigines (0.7%) had such elevated levels. By contrast, 89/142 (62.7%) patients with endoscopically proven duodenal ulcer had similarly elevated specific antibody levels. These differences were highly significant. We consider these findings to be consistent with the hypothesis that C. pylori is important in the pathogenesis of duodenal ulcer.