Association between β-thalassemia trait and myocardial infarction: a hospital-based case-control study

The association between β-thalassemia trait and myocardial infarction (MI) remains uncertain. Given the high prevalence of β-thalassemia in northern Iran, we investigated whether a β-thalassemia trait pattern identified by the Shine-Lal index is associated with MI in this population. This hospital-based case-control study included 497 participants (209 MI patients, 288 non-MI controls). Β-thalassemia trait was identified using the Shine-Lal index (< 1530), a validated CBC-based screening tool that does not replace confirmatory diagnostic methods. The trait was significantly less prevalent among MI patients than controls (9.1% vs. 21.2%; P < 0.001). In unadjusted analysis, thalassemia trait was associated with lower odds of MI (OR, 0.37; 95% CI, 0.21–0.64; P < 0.001). This association remained significant after adjustment for age, sex, hypertension, and diabetes mellitus (adjusted OR, 0.37; 95% CI, 0.21–0.64; P < 0.001). A β-thalassemia trait pattern identified by the Shine-Lal index was associated with significantly lower odds of MI in this hospital-based population. However, given the screening-based definition, the lack of confirmatory hemoglobin analysis, and hospital-based control selection, findings should be interpreted with caution and considered hypothesis-generating. Further prospective studies with confirmatory testing are warranted.