Prevalence of beta thalassemia carriers in India: a systematic review and meta-analysis.

A large number of studies have reported that the prevalence of beta thalassemia carriers in India varies by ethnic groups. The objective of this study was to conduct a systematic review of the published studies and conduct a meta-analysis to determine the prevalence of beta thalassaemia carriers in India. A PubMed database search using keywords "beta thalassaemia AND India" identified 1088 articles of which 69 articles were included in the review. Studies using diagnostic tests and methods recommended by the International Council for Standardization in Haematology were used for calculation of pooled prevalence. Pooled prevalence was calculated using a random effects model using Review Manager version 5.3. Studies had screened five categories of populations, that is, the general population; tribal groups, communities not belonging to tribal groups, persons with anemia, and persons referred with a suspicion of hemoglobinopathy. This heterogeneity contributed to a high pooled prevalence of beta thalassemia carriers of 8.23% (95% CI 7.36-9.10). Sub-group analysis however yielded 3.74% (95% CI 2.52-4.97) pooled prevalence of beta thalassemia carriers in the general population. It was 4.6% (95% CI 3.2-6.2) among tribal groups. Quality of prevalence studies was limited by methodological issues including non-random sampling methods, heterogeneity of population types screened, and lack of use of recommended diagnostic cut-offs. Prevalence of beta thalassemia carriers was similar in tribal populations and the general population, indicating the need to further investigate the prevalence of beta thalassemia carriers in tribal groups.