Prevalence and determinants of hemoglobinopathies among the Scheduled Tribes in the selected districts of Tamil Nadu, India: a community-based cross-sectional study

Inherited hemoglobin disorders (hemoglobinopathies) constitute a major public health challenge in India. The carrier frequency of β-thalassemia in the general Indian population is estimated to be approximately 3–4%, while substantially higher frequencies of inherited hemoglobin disorders have been reported among several tribal populations. These inherited disorders pose a major public health challenge due to genetic isolation, endogamy, and limited access to preventive services. However, evidence on the magnitude and determinants of hemoglobinopathies among scheduled tribes in Tamil Nadu remains limited. This study aims to estimate the prevalence of hemoglobinopathies and identify associated factors among the Scheduled Tribe communities residing in selected districts of Tamil Nadu. A community-based cross-sectional study was conducted among 400 Scheduled Tribes from four districts of Tamil Nadu, namely Kancheepuram, Salem, Nilgiris and Dharmapuri. Hemoglobinopathies were confirmed using combined hematological evaluation including complete blood count, reticulocyte count, peripheral smear examination, and high-performance liquid chromatography. Bivariate associations were assessed using the chi-square test, followed by multilevel mixed-effects logistic regression to identify factors independently associated with hemoglobinopathy status. Among the 400 study participants screened, 89 (22.3%) were confirmed to have hemoglobinopathies. The prevalence ranged from 2.5% among Irular to 34.8% among Kurumba tribes. The prevalence varied from district to district, ranging from 2.5% in Kancheepuram to 32.1% in Nilgiris and 34.6% in Dharmapuri. Bivariate analysis showed significant associations with terrain of residence and family size ( p < 0.05). In multilevel analysis, lower household income (≤ Rs.5,000) was independently associated with higher odds of hemoglobinopathies (AOR = 2.40; 95% CI: 1.31 to 4.41), while residence in plains demonstrated a protective effect (AOR = 0.04; 95% CI: 0.01 to 0.16). Substantial village-level and district-level clustering was observed and was largely explained after adjustment. Hemoglobinopathies impose a high and uneven burden among the Scheduled Tribal populations in Tamil Nadu. Regular screening strategies, strengthened genetic counselling, and integration of hemoglobinopathy services within primary healthcare systems are essential to reduce disease burden in high-risk tribal communities.