Body composition and lung function in cystic fibrosis and their association with adiposity and normal-weight obesity

Abstract

Objectives This study aimed to evaluate the relationship between lung function and body composition in cystic fibrosis (CF) and examine the presence of normal weight obesity (NWO), a high body fat percentage with a normal body mass index (BMI), in this population. Research Methods & Procedures In a pilot, cross-sectional study, 32 subjects with CF and a reference group of 20 adults without CF underwent body composition analysis with air displacement plethysmography. NWO was defined as a BMI <25 kg/m2 and body fat >30% (women) or >23% (men). Lung function in subjects with CF was determined by the percentage of predicted forced expiratory volume in 1 second (FEV1% predicted). Results Despite lower BMI and fat-free mass index (P<0.01), fat mass index and percent body fat did not differ between CF subjects and the reference group. Among CF subjects, FEV1% predicted was positively associated with fat-free mass index (β=6.31 ± 2.93, P=0.04) and inversely associated with fat mass index (β= −6.44 ± 2.93, P=0.04), after adjusting for age, gender and BMI. Ten CF subjects (31%) had NWO, which corresponded with lower fat-free mass index and FEV1% predicted compared to overweight subjects (P=0.006 and 0.004, respectively). Conclusions Excess adiposity, particularly in the form of NWO, was inversely associated with lung function in CF. Larger prospective studies should confirm these findings and determine the long-term metabolic and clinical consequences of excess adiposity in CF. As the lifespan of individuals with CF increases, nutrition screening protocols, which primarily rely on BMI, may require re-assessment.

Evaluating Changes in Handgrip Strength in Children With Cystic Fibrosis: A Pilot Study

“…HGS measures muscle function and detects changes in muscle mass sooner than BMI and other anthropometric measures in children >6 years . This pilot study was the first to use sex‐ and age‐adjusted HGS z scores as an indicator of malnutrition in children with CF and to indirectly measure LBM, which has a stronger association with pulmonary function than BMI . In addition, this was the first study to examine differences in HGS between days 5 and 7 of hospitalization and 6 weeks posthospitalization of a disease‐specific population.…”

“…Considerations to include in future studies are hospitalization vs nonhospitalization, CFRD, dependence on nutrition support, and physical activity level. An additional consideration for future studies is the growing concern of increased obesity in patients with CF and what role HGS may play in detecting such changes . Further investigation for timing of the HGS measurement would also be beneficial.…”

“…Stronger associations have been found between LBM and pulmonary function than BMI and pulmonary function in patients with CF . Decreases in LBM are associated with decreases in pulmonary function; however, LBM is not being routinely assessed in clinical settings…”

“…Stronger associations have been found between LBM and pulmonary function than BMI and pulmonary function in patients with CF. [8][9][10][11] Decreases in LBM are associated with decreases in pulmonary function; however, LBM is not being routinely assessed in clinical settings. 6 Methods to examine LBM include dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), bioelectrical impedance, phase angle, triceps skinfolds (TSF), mid-upper arm circumference (MUAC), arm muscle area (AMA), and ultrasound technology.…”

Impact of nutritional status on pulmonary function after lung transplantation for cystic fibrosis

“…5 Vitamin D deficiency has been associated with impaired lung function in non-transplanted CF patients, 6,7 and might be associated with an increased risk of rejection and infections after LT. 8 Subsequently, nutritional support has been shown to defer impairment of pulmonary function and improve survival in LT candidates. [9][10][11][12] However, data on the impact of nutritional status on lung function in LT recipients are limited.…”