Gender modifies the effect of body mass index on lung function decline in mild-to-moderate COPD patients: a pooled analysis

Wenjia Chen,Larry D Lynd,Mohsen Sadatsafavi,Don D Sin,J Mark Fitzgerald

doi:10.1186/s12931-021-01656-5

Abstract

BackgroundLow body weight is associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). However, it is not known whether gender modifies this relationship.MethodsWe pooled data of 8686 COPD patients from 7 studies with a median length of 36-months of follow up. Using a longitudinal natural cubic spline regression model, we examined the dose–response relationship between body mass index (BMI) and the rate of decline in forced expiratory volume in one second (FEV1) in patients with GOLD 1 and 2 disease, stratified by gender and adjusted for age, smoking status, and cohort effects.ResultsThere was an inverse linear relationship between BMI and the rate of FEV1 decline in GOLD Grades 1 and 2, which was modified by gender (p < 0.001). In male patients, an increase of BMI by 1 kg/m2 reduced FEV1 decline by 1.05 mL/year (95% CI 0.96, 1.14). However, in female patients, BMI status did not have a clinically meaningful impact on FEV1 decline: an increase of baseline BMI by 1 kg/m2 reduced FEV1 decline by 0.16 ml/year (95% CI 0.11, 0.21). These gender-modified relationships were similar between GOLD 1 and 2 patients, and between current and former smokers.ConclusionIn mild to moderate COPD, higher BMI was associated with a less rapid decline of FEV1 in male patients whereas this association was minimal in females patients. This gender-specific BMI effect was independent of COPD severity and smoking status.

Highlights

Low body weight is associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD)
While multiple studies report that those with low body mass index (BMI) may be at risk of COPD progression and those who are obese may be protected [5, 6], others have shown no significant association between BMI and FEV1 decline [11, 12]
By pooling data from these 7 cohorts, the final study sample included patients with mostly mild and moderate COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity grades at baseline (GOLD Grade 1, FEV1 ≥ 80 percent of predicted at 25 years of age, mild COPD; and Grade 2, FEV1 50–79 percent predicted, moderate COPD)

Summary

Introduction

Low body weight is associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). It is not known whether gender modifies this relationship. While multiple studies report that those with low body mass index (BMI) may be at risk of COPD progression and those who are obese may be protected [5, 6], others have shown no significant association between BMI and FEV1 decline [11, 12]. We pooled individual-level data from 7 large international studies into a single, combined dataset, and examined the dose–response relationship between BMI and the rate of FEV1 decline in patients with mild and moderate COPD, according to gender and smoking status

Methods

Results

Discussion

Conclusion