ABO blood group as a risk factor for tuberculosis: A network meta-analysis.

BACKGROUND

Despite numerous studies on ABO blood group and risk of tuberculosis, no consensus has been reached.

METHODS

We conducted a systematic review following the Meta-Analysis of Observational Studies in Epidemiology group statement. English language articles providing odds ratio data regarding tuberculosis risk among ABO groups were eligible. Least-squares approach random-model network and random-model pairwise meta-analyses were conducted. The protocol-specified primary outcome was tuberculosis risk among ABO groups in the form of odds ratios calculated via a network meta-analysis.

RESULTS

We identified 28 studies with 30 populations comprising 15,664 patients with tuberculosis and 254,610 controls. Subjects with AB blood type had a higher risk of becoming infected with tuberculosis than those with blood type O (odds ratio (OR) = 1.26, 95% confidence interval (CI): 1.14-1.38), A (OR = 1.25, 95% CI: 1.14-1.38), and B (OR = 1.22, 95% CI: 1.11-1.34). Pairwise comparison revealed that AB blood type was a risk factor for tuberculosis with OR = 1.23 (95% CI: 1.02-1.48) compared to other blood types. Region-based subgroup analyses suggested that the AB blood group was a substantial risk in Africa (OR = 1.78, 95% CI: 1.39-2.28) and India (OR = 1.48, 95% CI: 1.14-1.92).

CONCLUSIONS

AB blood group is a risk factor for tuberculosis of a substantial magnitude in Africa and India.