Patterns of Body Composition Relating to Chronic Respiratory Diseases Among Adults in Four Resource-Poor Settings in Peru

Variation of All-Cause Mortality with Fat-Free Mass Index (FFMI) and Fat Mass Index (FMI) in Individuals with Asthma: Results from the NHANES Database Retrospective Cohort Study

BACKGROUND

The relationship between fat-free mass index (FFMI), fat mass index (FMI), and mortality in patients with asthma remains unknown. This study aimed to examine the associations between FFMI and FMI and all-cause mortality in a cohort of American adults diagnosed with asthma.

METHODS

This study included 15,200 adults from NHANES. To assess mortality, we linked participant records to the National Death Index. FMI and FFMI were measured and evaluated using dual-energy X-ray absorptiometry (DXA). Survival differences across quintiles of FFMI and FMI were explored using Kaplan-Meier plots and log-rank tests, with the proportional hazards assumption assessed using Schoenfeld residuals. Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) for mortality associated with FFMI and FMI, adjusting for potential confounders including age, sex, smoking status, physical activity, and other relevant factors. Additionally, stratified analyses based on theoretical considerations were conducted to identify subgroups of individuals exhibiting an elevated risk of mortality. This study also examined the nonlinear relationships between FFMI, FMI, and mortality using restricted cubic splines (RCS).

RESULTS

After a median follow-up of 184 months, 12.11% of individuals had died. Kaplan-Meier plots revealed significant differences in all-cause mortality among patients with asthma across the FFMI and FMI quintiles. Specifically, individuals in the lowest FFMI quintile (Q1, 10.4-16.0, representing the range of FFMI values) exhibited a significantly increased risk of all-cause mortality (HR: 4.63; 95% CI: 1.59, 13.5; p < 0.01). Similarly, elevated risks of all-cause mortality were observed in the upper three quintiles of FMI, with Q3 (4.8-6.1) having an HR of 2.9 (95% CI: 1.20, 7.00; p < 0.05), Q4 (6.2-8.3) having an HR of 3.37 (95% CI: 1.41, 8.03; p < 0.01), and Q5 (8.4-22.8) having an HR of 4.6 (95% CI: 1.31, 16.2; p < 0.05). Moreover, the risk of all-cause mortality increased with increasing FMI and decreasing FFMI (p for non-linearity < 0.001 in both cases). Subgroup analyses further elucidated these associations across different categories. In examining the association between FMI and all-cause mortality among asthma patients across various subgroups, a heightened mortality risk found among males, individuals with medium education levels, medium income levels, and those who consume alcohol.

CONCLUSIONS

The study shows that both high FMI and low FFMI are associated with increased mortality in patients with asthma. These findings underscore the critical role of FMI and FFMI in the health management of asthma patients. Therefore, it is recommended that clinicians proactively monitor and adjust these indices to improve patient prognosis and enhance health outcomes for individuals with asthma..

Association between appendicular lean mass and chronic obstructive pulmonary disease: epidemiological cross-sectional study and bidirectional Mendelian randomization analysis

Background

The association of BMI with COPD, and sarcopenia in COPD have been both confirmed by several studies, but research on the relationship and causality of body lean mass and the risk of chronic obstructive pulmonary disease (COPD) remains to be discovered. The purpose of this study was to explore the association between lean mass and COPD risk as well as to further examine the causal relationship in the findings.

Methods

Three thousand four hundred fifty-nine participants from NHANES 2013-2018 were included in the epidemiological cross-sectional study to assess the association between relative lean mass and COPD by restricted spline analysis (RCS) and weighted multiple logistic regression. Furthermore, to verify the causality between lean mass and COPD, a two-sample Mendelian randomization (MR) with inverse variance weighting (IVW) method was used to analyze GWAS data from European ancestry. Genetic data from the United Kindom Biobank for appendicular lean mass (450,243 cases) and lung function (FEV₁/FVC) (400,102 cases) together with the FinnGen platform for COPD (6,915 cases and 186,723 controls) were used for MR.

Results

Weighted multiple logistic regression showed a significant correlation between relative appendicular lean mass and COPD after adjusting for confounders (OR = 0.985, 95% CI: 0.975-0.995). Compared to the lower mass (155.3-254.7) g/kg, the high mass (317.0-408.5) g/kg of appendicular lean apparently decreases the risk of COPD (OR = 0.214, 95% CI: 0.060-0.767). Besides, in the analysis of MR, there was a forward causality between appendicular lean mass and COPD (IVW: OR = 0.803; 95%CI: 0.680-0.949; p = 0.01), with a weak trend of causality to lung function.

Conclusion

Our study not only found an inverse association between appendicular lean mass and COPD but also supported a unidirectional causality. This provided possible evidence for further identification of people at risk for COPD and prevention of COPD based on limb muscle exercise and nutritional supplementation to maintain skeletal muscle mass.

Phase angle in assessment and monitoring treatment of individuals with respiratory disease

Phase angle (PhA) represents a raw variable measured with bioelectrical impedance analysis (BIA) that is used to assess malnutrition in many diseases, including respiratory diseases, mainly chronic obstructive pulmonary disease (COPD). COPD patients with reduced PhA are older, more hypoxic and hypercapnic; patients with more severe COPD have reduced cell mass, evident skeletal muscle depletion, and worsening gas exchange. Malnourished patients with stable COPD in long-term oxygen therapy (LTOT) have more intense dyspnea at rest, greater weight loss over the past 12 months, and more exacerbations per year. Multiple regression analysis highlighted the significance of PhA° in the estimation of muscle strength: hand grip strength (HGS) and in that of respiratory muscles: maximal inspiratory pressure / max. expiratory pressure ratio (MIP/MEP). Furthermore, the relationship between PhA° and all-cause mortality in COPD patients was confirmed with the Cox regression model, Kaplan-Meier test, and log-rank tests. The role of malnutrition in idiopathic pulmonary fibrosis (IPF) is confirmed by the PhA° measurements which, regardless of body weight, is associated with the reduction in muscle mass of these patients, reduces their strength and exercise capacity, and greatly influences the prognosis. In conclusion PhA is a novel biomarker of morbidity and mortality in patients with severe respiratory diseases.