Higher body mass index was associated with lower mortality and slower lung function decline among patients with interstitial lung disease, according to a systematic review and meta-analysis of 25 articles encompassing 29 studies and 23,741 patients.
Interstitial lung disease encompasses a heterogeneous group of fibrotic lung disorders. In the analysis, researchers evaluated the association between body mass index and clinical outcomes, including mortality, hospitalization, and lung function, using data from PubMed/MEDLINE, Embase, and the Cochrane Library through May 2024. Outcomes included 24 mortality studies, four hospitalization studies, and multiple analyses of baseline and longitudinal lung function.
Patients with obesity had lower mortality compared with those without obesity. Similarly, higher body mass index as a continuous measure was associated with a lower likelihood of mortality. These findings were generally consistent across geographic regions, antifibrotic use, and interstitial lung disease subtype, although categorical comparisons reached statistical significance primarily in studies conducted after 2014 and in those focused on idiopathic pulmonary fibrosis.
Across four studies, lower body mass index was associated with a higher likelihood of hospitalization in univariable analyses. However, multivariable analyses showed only marginal statistical significance, and results varied across studies.
In analyses of baseline lung function, patients with obesity had lower forced vital capacity but higher diffusing capacity for carbon monoxide compared with those without obesity. In five studies evaluating longitudinal change, patients with obesity experienced a slower annual decline in forced vital capacity.
Subgroup analyses showed that reduced baseline forced vital capacity remained statistically significant in non-Asian studies, studies that included antifibrotic therapy, and non–idiopathic pulmonary fibrosis groups. Higher diffusing capacity for carbon monoxide was observed in select subgroups, including non-Asian populations and studies conducted before 2014.
About half of the included articles were cohort studies, and most were assessed as having a moderate risk of bias. Sensitivity analyses showed consistent directions of effect for mortality and lung function outcomes, although statistical significance varied depending on the analytic approach. Publication bias was identified in some mortality analyses, but adjusted estimates remained consistent.
The researchers noted several limitations, including the retrospective observational design of included studies, heterogeneity in interstitial lung disease subtypes, region-specific definitions of obesity, and incomplete adjustment for confounders. Approximately 90% of the study population comprised patients with idiopathic pulmonary fibrosis, which may limit generalizability.
“BMI should be interpreted as a marker of overall health status rather than a direct therapeutic target,” the researchers concluded.
The researchers reported no conflicts of interest.
Source: Frontiers in Medicine
