Handgrip Strength in Chronic Obstructive Pulmonary Disease. Associations with Acute Exacerbations and Body Composition

Abstract

Rationale: Handgrip strength (HGS) predicts mortality in the elderly, but its determinants and clinical significance in chronic obstructive pulmonary disease (COPD) has not been defined.

Objectives: We tested associations of HGS with pectoralis muscle area (PMA), subcutaneous adipose tissue (SAT), imaging characteristics, and lung function in smokers with COPD, and evaluated the cross-sectional and longitudinal associations of HGS with acute respiratory events.

Methods: We analyzed demographic, clinical, spirometry, HGS, and imaging data of 272 subjects with COPD, obtaining measures of airway thickness, emphysema, PMA, and SAT from chest computed tomography scans. We tested associations of lung function and imaging characteristics with HGS, using linear models. HGS association to acute respiratory events at enrollment and during follow-up (mean, 2.6 years) was analyzed using adjusted logistic models.

Results: HGS correlated with PMA, SAT, forced expiratory volume, and airway thickness, but not with body mass index or emphysema severity. In adjusted regression models, HGS was directly (β, 1.5; 95% confidence interval [CI], 0.1-3.0) and inversely (β, -3.3; 95% CI, -5.1 to -0.9) associated with one standard deviation of PMA and SAT, respectively, independent of body mass index and emphysema. In regression models adjusted for age, sex, body mass index, race, pack-years smoked, current smoking, chronic bronchitis, FEV1% predicted, emphysema, and airway metrics, HGS was associated with exacerbation risk; in cross-sectional analyses, there was an increment of 5% in the risk of exacerbations for each 1-kg decrement in HGS (risk ratio, 1.05; 95% CI, 1.01-1.08), and there was a similar risk during follow-up (risk ratio, 1.04; 95% CI, 1.01-1,07).

Conclusions: In ever-smokers with COPD, HGS is associated with computed tomography markers of body composition and airway thickness, independent of body mass index and emphysema. Higher HGS is associated with lower exacerbation frequency.

Keywords: Body Mass Index; COPD symptom flare up; adult; cohort studies; computed tomography.

Figures

Figure 1.

Flow of participants included in the study. COPD = chronic obstructive pulmonary disease; GOLD = Global Initiative for Obstructive Lung Disease.

Figure 2.

Correlation between handgrip strength and imaging markers of body composition. The scatterplots show the correlations between handgrip strength and (A) pectoralis muscle area (r = 0.39), (B) subcutaneous fat area (r = −0.34), and (C) body mass index (r = 0.05).

Figure 3.

Differences in handgrip strength by body composition and imaging groups. The association between low pectoralis muscle area and low handgrip strength (A) is present, regardless of body mass index (BMI). In a similar manner, higher subcutaneous tissue area is associated with low handgrip strength (B), even if the subject has normal body mass index. All comparisons are based on two-way analyses of variances, corrected for multiple comparisons.