Several lines of evidence suggest that, of the three main races of Singapore, peptic ulcers are more common among the Chinese and Indians when compared to the Malays. These include studies on hospital series of patients with or without appropriate control groups, studies on the incidence of surgery for perforated ulcer as well as mortality statistics. A reduction in the Chinese:Malay difference in the incidence of perforated ulcer over three decades suggests that environmental factors are involved in producing these racial differences. However, we have to date been unable to determine the factor(s) responsible. The incidence of perforated ulcer in Singapore is increasing while ulcer mortality is declining. This is similar to the situation in Hong Kong but different from that in the western countries.
Observations of racial differences in the prevalence of Helicobacter pylori in Malaysia have been intriguing. The Indians and Chinese consistently have a higher prevalence compared to the Malays. The racial cohort theory has been proposed to explain these differences where transmission and perpetuation of infection takes place within a racial group rather than between races, races being separate owing to the low rate of interracial marriages. Studies have demonstrated distinctive bacterial strains between races. Phylogenetic studies have shown that H. pylori isolates amongst Chinese and Indians are distinctive while Malays have Indian and other strains suggesting a more recent acquisition of the bacterium from Indians. H. pylori is recognized as the major causative factor in peptic ulcer disease and gastric cancer. Despite the high prevalence of H. pylori, Indians have a relatively low prevalence of peptic ulcer disease and a low incidence of gastric cancer. This paradox with regards to gastric cancer has been termed the "Indian enigma". Bacterial strain differences between races may be putative but this observation may also indicate gastroprotective environmental factors or a lower genetic susceptibility to develop cancer in the Indians.
Peptic ulcer occurs with different frequencies in the three main racial groups in Singapore. This study aimed firstly to determine the prevalence of Helicobacter pylori in peptic ulcer and non-ulcer dyspepsia patients of the different races and secondly, to assess the relation between H pylori, histological gastritis, patient diagnosis, and race. Gastric antral biopsy specimens from 1502 patients undergoing gastroduodenoscopy were studied and 892 (59%) were positive for H pylori. H pylori was strongly associated with gastritis: 873 of 1197 (73%) patients with gastritis were positive compared with 19 of 305 (6%) without gastritis (p less than 0.0001). The prevalences of H pylori and gastritis were similar in peptic ulcer patients of different races. Malay patients with non-ulcer dyspepsia, however, were less likely to be positive for H pylori (10 of 46 (22%] or to have antral gastritis (17 of 46 (37%] than Chinese (292 of 605 (48%) were positive for H pylori and 421 of 605 (70%) had gastritis) and Indians (35 of 61 (57%) were H pylori positive and 42 of 61 (69%) had gastritis). Patients with duodenal ulcer were more likely to be positive for H pylori than those with non-ulcer dyspepsia, even when subjects with gastritis were considered separately. While our results do not help to explain the observed racial differences in peptic ulcer frequency it may be that the pathophysiology of non-ulcer dyspepsia is different in the different races in Singapore.
This study was conducted to determine the prevalence of Helicobacter pylori (H. pylori) and its associated factors among patients with peptic ulcer disease in Taiping Hospital. Consecutive peptic ulcer disease patients who had undergone esophagogastro-duodenoscopy were included. The H. pylori status was assessed by the rapid urease test. We excluded those who had active bleeding, a perforated peptic ulcer, severe vomiting, a history of gastric surgery, peptic ulcer disease or renal or liver diseases, carcinoma of the stomach, and recent use of antibiotics or proton pump inhibitors. Socio-demography, H. pylori status, medication history and other relevant clinical data were collected from case notes. A total of 416 subjects were selected, 49.7% were positive and 50.3% were negative for H. pylori infection. There were significant associations between H. pylori and age, ethnicity, smoking status and NSAID usage. However, there were no significant relationships between H. pylori status and gender or type of peptic ulcer. Multiple logistic regression showed that other ethnicities than Malays and smokers had a higher risk of H. pylori. Our prevalence rate was low and the identified risk factors were consistent with previous studies. Ethnic differences may be related to genetic and sociocultural behaviors. Quitting smoking may benefit peptic ulcer patients with H. pylori infection.
Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3' region of cagA gene were examined among 192 Malaysian H. pylori cagA-positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621-651bp), type B (732-735bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p>0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific-cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p<0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p<0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection.
Marked epidemiological changes in upper gastrointestinal diseases and Helicobacter pylori infection have taken place in the Asian Pacific region. In particular, differences with respect to race in the multiracial Asian population in Malaysia have been important and interesting.