Continuous fat-free mass decline in COPD: fact or fiction?

Abstract

Patients with chronic obstructive pulmonary disease (COPD) generally have lower fat-free mass (a surrogate marker of skeletal muscle mass) compared with their healthy peers [1,2], and this is associated with decreased functional capacity [3], the presence of other comorbidities (e.g. osteoporosis and renal impairment) [4] and increased mortality risk [5]. To date, longitudinal observational studies have shown no difference in the mean decline in fat-free mass over time between COPD patients and non-COPD control subjects [6,7]. However, it remains unknown whether and to what extent a subgroup of COPD patients suffer continuous loss of fat-free mass. We hypothesised that COPD patients have 1) a higher prevalence of continuous fat-free mass decline, and 2) that this subgroup has a steeper decline of fat-free mass compared with a non-COPD control group with a continuous fat-free mass decline. We tested this hypothesis in the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study, which had a 3 year follow-up period.The design, aims and methodology of ECLIPSE have been described elsewhere [8]. Fat-free mass was measured by a trained research nurse using bio-electrical impedance (Bodystat 1500; Bodystat Ltd, Douglas, UK) (each centre had the same device) after at least 4 h fasting and calculated with a COPD specific formula [9]. Only subjects with complete fat-free mass data throughout the study were included in the present analysis. Low attenuation was determined by a chest computed tomography scan. Decline was defined as any fat-free mass measurement during follow-up that was lower than the fat-free mass of the previous year, and the number of years with a fat-free mass decline was summed. The prevalence of 3-year fat-free mass decline was calculated. Severe (hospitalisations) and moderate (use of corticosteroids/ antibiotics) exacerbations during the 3 year follow-up were recorded. Frequent exacerbators were defined as those patients with at least two exacerbations per year in the 3 year follow-up. The Chi-squared test was used to test the prevalence of fat-free mass decline between the COPD patients and the non-COPD control group. The unpaired t-test was used to compare the characteristics and level of decline in the patient group with the control group, and the characteristics in the group with a continuous decline compared with the remaining group. A p-value <0.05 was considered statistically significant.

Precision medicine in COPD: where are we and where do we need to go?

“…This concept was particularly relevant, given the concerns that ICS increase the risk of pneumonia and systemic side-effects [ 36 ]. One investigative group described a greater increase in ICS-related pneumonia risk in current smokers, patients with prior pneumonia, those with a body mass index <25 kg·m −2 and severe airflow limitation [ 37 ]. Similarly, this benefit–risk approach was adopted by the GOLD therapeutic strategy in interventional lung volume reduction based on clinical phenotyping.…”

Somatotypes trajectories during adulthood and their association with COPD phenotypes

“…This is unlikely to be conducted. Unfortunately, most COPD epidemiological studies have a relatively short observation period [42,43], and there may not be detailed measurements over time to define the specific phenotypes in the cohorts used to establish lung function trajectories [2].…”

Somatotypes trajectories during adulthood and its association with Chronic Obstructive Pulmonary Disease (COPD) phenotypes

“…This is unlikely to be conducted. Unfortunately most COPD epidemiologic studies have a relative short observation period (43,44) and the cohorts used to establish lung function trajectories may not have detailed measurements over time to define the specific phenotypes(3).…”