Racial differences in the prevalence of heartburn

Authors


Sirs, We read with interest the article by Wong et al. on the prevalence of gastro-oesophageal reflux disease (GERD) in a Chinese population1 and that by Spechler et al. on racial differences in GERD.2 We would like to share our own data on racial disparity in the prevalence of heartburn in an ethnically mixed non-migrant Asian population.

The prevalence of GERD amongst Asians has been reported to be low and has been attributed to a lack of a word for heartburn in the Chinese language, the smaller body mass of Asians, the low-fat Asian diet3 and the high prevalence of Helicobacter pylori infection.4 Indeed, there is no word for heartburn in certain other languages spoken in Asia, e.g. Tamil and Malay. Not surprisingly, Spechler et al. found significant differences amongst racial groups in the reporting, understanding and experience of heartburn, which were exceedingly low in East Asians (2.6%) when compared with Caucasians (34.6%) and Afro-Americans (46.1%).2

Studies from Taiwan report prevalence rates for erosive oesophagitis and Barrett's oesophagus of 15% and 2%, respectively, both of which approach those of published Western reports.5, 6 Our own data from Malaysia reveal a prevalence rate of endoscopically documented oesophagitis of 6% and a similar value for biopsy-proven Barrett's oesophagus8 (both long and short segments), i.e. not dissimilar to published Western data.7 In view of the conflicting prevalence data on GERD in different geographical locations within Asia and the ethnic differentiation in the prevalence of oesophagitis and Barrett's metaplasia, we studied the prevalence of heartburn and health care-seeking behaviour in a multi-racial population. Furthermore, we sought to determine the proportion seeking treatment for GERD, be it Western or alternative medicine.

In our cross-sectional study, we used the Gastrointestinal Symptoms Questionnaire previously validated in an Asian (Singaporean) population with a similar multi-racial mix, provided by Ho et al.8 Our questionnaire contained 24/121 response items in relation to GERD in the last year. Heartburn was defined as a burning feeling rising from the stomach or lower chest up towards the neck, and acid regurgitation as a very sour or acid-tasting fluid at the back of the throat. In particular, the severity and duration of heartburn, nocturnal awakening and aggravating and relieving factors were all included in the questionnaire, as were frequent psychosomatic symptoms.

The study population was from the State of Perak (population, approximately 2 million) whose ethnic composition is as follows: Malays, 51.4%; Chinese, 31.3%; Indians, 12.8%; others, 4.5%.9 This ethnic distribution and basic demographic characteristics are representative of the rest of west Malaysia. Subjects were identified from the National Household Sampling Frame created for the 2000 Population and Housing Census.9 Subjects were recruited from both rural and urban areas using a race-stratified disproportionate random sampling procedure to ensure a sufficient number of members of ethnic minorities. To avoid ethnic ambiguity, only subjects without racial admixture in the immediate two preceding generations were recruited. A team of interviewers trained by one physician (SR) interviewed the subjects at home in the languages/dialect usually understood and spoken by the respondents.

Subjects aged 18–81 years (mean, 33.6 years; standard deviation, 13 years), who were successfully interviewed and analysed, totalled 949 (478 males, 471 females), consisting of 314 Chinese, 314 Malays and 321 Indians. Heartburn at least once a year was reported by 319 (33.6%) respondents, with a female to male ratio of 1.3. Monthly and weekly prevalence rates were 31 (9.7%) and 19 (6.0%), respectively. The prevalence of annual heartburn by ethnic group was as follows: Chinese, 92 (29.3%); Malays, 91 (29%); Indians, 136 (42.4%) (Indians vs. Chinese: odds ratio, 1.77; 95% confidence interval, 1.26–2.50; P < 0.001; Indians vs. Malays: odds ratio, 1.80; 95% confidence interval, 1.28–2.54; P < 0.001). The race-standardized annual prevalence of heartburn was 30.3%. The severity of heartburn was mild in 170 subjects (53.3%), moderate in 128 (40.1%) and severe in 21 (6.6%). Nocturnal awakening due to heartburn was reported by 64 symptomatic subjects (20.1%). Of those with heartburn, 143 (44.8%) had consulted a doctor and 179 (56.1%) had taken medication for their symptoms, six (6.7%) of whom had sought alternative medicine treatment.

Heartburn amongst Malaysians was mostly of a milder grade and was less than that reported in Western populations. Indians had the highest prevalence of heartburn, in keeping with our recent study which showed a similar racial predilection for GERD complications.7 In Singapore, Ho et al. reported that reflux symptoms were twice as common in Indians than Chinese, although we cannot fully explain their exceedingly low monthly heartburn prevalence of 1.6%.8 Heartburn is probably known by another name in Asia, which may contribute to low symptom reporting and a consequently low physician referral for endoscopic examination. There was no difference in the prevalence of heartburn between Malays, who are exclusively Muslim and therefore abstain from alcohol, and Chinese, who are predominantly of Buddhist or Christian faith and therefore not prohibited from consuming alcohol. These findings suggest the possibility of a genetic component to GERD, as demonstrated in severe paediatric reflux disease,10 although racial differences in the exposure to local environmental factors, such as dietary fat consumption and the prevalence of cagA-positive H. pylori, cannot be excluded. These ethnic differences warrant further study to establish a genetic and/or environmental aetiology.

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