Estimating the burden of α-thalassaemia in Thailand using a comprehensive prevalence database for Southeast Asia

Severe forms of α-thalassaemia, haemoglobin H disease and haemoglobin Bart’s hydrops fetalis, are an important public health concern in Southeast Asia. Yet information on the prevalence, genetic diversity and health burden of α-thalassaemia in the region remains limited. We compiled a geodatabase of α-thalassaemia prevalence and genetic diversity surveys and, using geostatistical modelling methods, generated the first continuous maps of α-thalassaemia mutations in Thailand and sub-national estimates of the number of newborns with severe forms in 2020. We also summarised the current evidence-base for α-thalassaemia prevalence and diversity for the region. We estimate that 3595 (95% credible interval 1,717–6,199) newborns will be born with severe α-thalassaemia in Thailand in 2020, which is considerably higher than previous estimates. Accurate, fine-scale epidemiological data are necessary to guide sustainable national and regional health policies for α-thalassaemia management. Our maps and newborn estimates are an important first step towards this aim.

Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Birth defects in the newborn population: race and ethnicity

BACKGROUND

Racial variability in certain prenatal risk factors, such as prenatal vitamin supplementation and termination of pregnancy for fetal anomaly, has altered the racial prevalence of birth defects. Analysis of a single large representative population is required to analyze current racial differences in the prevalence of birth defects in the United States.

METHODS

This is a population-based cross-sectional study to analyze racial differences in the prevalence of birth defects. We reviewed all live births in the 2008 Nationwide Inpatient Sample (NIS) database and determined birth prevalence of 55 selected birth defects in Caucasians. We then calculated the relative risk of these birth defects in African-Americans, Hispanics, and Asians relative to Caucasians.

RESULT

Overall birth defect prevalence was 29.2 per 1000 in a cohort of 1,048,252 live births, of which 51% were Caucasians. Compared with Caucasians, the risk of overall birth defects was lower in African-Americans (relative risk = 0.9, confidence interval 0.8-0.9) and Hispanics (relative risk = 0.9, confidence interval 0.8-0.9). The risk of overall birth defects was similar in Caucasians and Asians. Relative to the Caucasians, African-Americans had a lower risk of cardiac, genitourinary, and craniofacial malformations but a higher risk of musculoskeletal malformations. Hispanics had a lower risk of genitourinary and gastrointestinal malformation. Asians had a higher risk of craniofacial and musculoskeletal malformations.

CONCLUSION

This is a comprehensive description of racial differences in the risk of birth defects in the United States. Observed racial differences in the risk of birth defects may be related to genetic susceptibilities, to cultural or social differences that could modify exposures, or to the many potential combinations between susceptibilities and exposures.