Risk factors associated with mortality in hypersensitivity pneumonitis:
a meta-analysis
Abstract
Background: Hypersensitivity pneumonitis (HP), an immune-mediated form
of diffuse parenchymal lung disease (DPLD), is triggered by inhalation
of a wide variety of allergens in susceptible individuals. Several
studies suggest that the death rate associated with this disease has
increased significantly in recent years. This meta-analysis investigates
the significant clinico-radiological characteristics which may be
appraised as potential risk factors associated with disease mortality.
Methods: Extensive literature search was conducted for original articles
published between 1st January 2009 and 30th April 2021 through PubMed,
Google Scholar, EMBASE, and Cochrane Library using the keywords:
“hypersensitivity pneumonitis”, “hazard ratio” and “mortality”.
Results: A total of 21 independent studies related to mortality of HP
subjects could be identified. The combined results of univariate and
multivariate analysis suggest that older age [univariate odds ratio
(OR): 1.038; multivariate OR: 1.036], male subjects [univariate OR:
1.508; multivariate OR: 1.396], honeycombing [univariate OR: 1.086;
multivariate OR: 1.121] and traction bronchiectasis [univariate OR:
1.141; multivariate OR: 1.107] are significantly associated with
mortality risk of HP subjects. Further, forced vital capacity, diffusing
capacity for carbon monoxide, ground glass opacity and mosaic
attenuation were associated with lower risk of all-cause mortality.
Although smoking status correlated with mortality risk, the findings
appeared to be insignificant. Conclusion: Individual male subjects with
older age and presence of extensive fibrosis, i.e., honeycombing and
traction bronchiectasis experience an increased mortality risk.
Additional observational and interventional studies are required to
validate the findings and to identify extent of the risk factors and
their association with disease mortality.