S1 Data -

Background
Anemia is a globally well-known major public health problem. In Southeast Asia where there is ethnic diversity, both iron deficiency (ID) and inherited hemoglobin disorders (IHDs) are prevalent and are considered to be the major factors contributing to anemia. However, little is known about the anemia burden among the ethnic minorities. In this study, we determine the burden of anemia, in relation to ID and IHDs, among the Karen ethnic minorities living in the rural area of lower northern Thailand.
Methods
A cross-sectional community-based study was conducted at Ban Rai district, Uthai Thani province. Study participants included 337 Karen people aged over 18 years. Socio-economic and health-related information were obtained through interviews and recorded by local health staff. Anemia, IHDs and ID were diagnosed according to standard laboratory methods. Multivariate logistic regression analysis was applied to identify risk factors of moderate-to-severe anemia.
Results
The prevalence of overall anemia was 27.9% (95% CI = 23.2–33.0). Mild and moderate anemia were detected in 18.7% (95% CI = 14.7–23.3) and 8.9% (95% CI = 6.1–12.5) respectively. Severe anemia was found in one case (0.3%). Various forms of IHDs were identified in 166 participants, constituting 49.3% (95% CI = 43.8–54.7). The most common form of IHDs was α+-thalassemia (32.9%), followed by β-thalassemia (12.2%), α0-thalassemia (4.2%), hemoglobin E (3.9%), and hemoglobin Constant Spring (0.9%). Among 308 participants who were investigated for ID, the prevalence was discovered to be 6.8% (95% CI = 4.3–10.2). Analysis of risk factors of moderate-to-severe anemia revealed that individuals with ID, β-thalassemia and age > 65 years were at high risk with adjusted odds ratio of 17 (95% CI = 3.8–75.2), 6.2 (95% CI = 1.4–27.8) and 8.1 (95% CI = 1.6–40.4) respectively.
Conclusions
Anemia among the Karen is of public health significance; and IHDs are the major contributing factors. Because of the high risk of developing moderate-to-severe anemia, special attention should be paid to individuals affected with ID, β-thalassemia and the elderly. Public awareness of the health burden of severe thalassemia syndromes should also be campaigned.