The causal relationship between bronchiectasis and non-tuberculous mycobacteria infections: A bidirectional Mendelian...

Observational studies have suggested a bidirectional association between bronchiectasis and non-tuberculous mycobacteria (NTM) infections. However, the causal association between bronchiectasis and NTM infection remains unclear. This study is aimed to investigate whether bronchiectasis and NTM infection are causally related.

The data related to bronchiectasis and NTM infection were collected from the IEU Open GWAS project. A bi-directional Mendelian randomization (MR) analysis was performed to examine the direction of the causal relation between bronchiectasis and NTM infection. Meta-analysis would be conducted if the results of MR were inconsistent.

Bronchiectasis increased NTM infection risk, with an odds ratio (OR) of 1.42 (Dataset:finn-b-MYCOBLUNGATYPICA, 95% CI: 1.09-1.85; p = 0.009) and 1.32 (Dataset: finn-b-AB1_OTHER_MYCOBAC, 95% CI: 1.02, 1.71; p = 0.036) from the bronchiectasis (1107 bronchiectasis cases and 186,723 controls) genome-wide association study, respectively. On the other hand, NTM infection (Dataset:finn-b-MYCOBLUNGATYPICA) increased the risk of bronchiectasis, with an OR of 1.06 (95% CI: 1.02-1.11; p = 0.007). However, there was no evidence of a causal effect of NTM infection (Dataset: finn-b-AB1_OTHER_MYCOBAC) on the risk of bronchiectasis, with an OR of 1.02 (95%CI: 0.96-1.08; p = 0.57). In meta-analysis based on the two datasets, NTM infection was associated with an increased risk of bronchiectasis, with an OR of 1.05 (95% CI: 1.01-1.08; p < 0.001).

Bronchiectasis increases the risk of NTM infection and vice versa, which indicate the need for vigilant monitoring and management of both conditions to mitigate their interrelated risks.