Expiratory muscle strength and functional exercise tolerance in adults with cystic fibrosis: a cross-sectional study.

OBJECTIVE: A 6-minute walk work (6MWW), that is the product of distance walked at the 6-minute walk test (6MWT) multiplied by body weight, has been suggested as an appropriate variable for estimating functional capacity. Under the hypothesis that 6MWW strongly correlates with expiratory muscle strength (PE max), as found in Chronic Obstructive Pulmonary Disease (COPD), the aim of the study was to determine the degree of this correlation in adults with cystic fibrosis. METHODS: A cross-sectional study was carried out at the Regional Referral Centre for Cystic Fibrosis, where patients with cystic fibrosis attending their regular follow-up, aged 18 years or older with mild-to-normal lung disease, were asked to participate. Dietitians determined nutritional status before subjects performed spirometry and static measurement of respiratory muscles. The 6MWT was performed as the last study procedure. Spearman correlation test was used to correlate PE max with 6MWW and other study variables. RESULTS: Twenty-five cystic fibrosis subjects aged 18-30 years and with FEV1 values ranging from 42.4% to 123.4% predicted completed the study. PE max strongly correlated with 6MWW (rho .72, p = .0001) whereas it did not correlate with other study variables, including distance at the 6MWT. Distance walked multiplied by body weight (p = .0019) and body mass index (p = .0238) were significantly lower in those with PE max below the lower limits of normal. CONCLUSION: Increased functional exercise tolerance is related to higher static expiratory pressure in patients with mild-to-normal cystic fibrosis lung disease. Difference in exercise performance might reflect a possible difference in body composition that needs to be further investigated.

Nutritional status, nutrient intake and use of enzyme supplements in paediatric patients with Cystic Fibrosis; a European multicentre study with reference to current guidelines.

BACKGROUND: The New European guidelines have established the most updated recommendations on nutrition and pancreatic enzyme replacement therapy (PERT) in CF. In the context of MyCyFAPP project - a European study in children with CF aimed at developing specific tools for improvement of self-management - the objective of the current study was to assess nutritional status, daily energy and macronutrient intake, and PERT dosing with reference to these new guidelines. METHODS: Cross sectional study in paediatric patients with CF from 6 European centres. SD-scores for weight-for-age (WFA), height-for-age (HFA) and body mass index-for-age (BMI) were obtained. Through a specific 4-day food and enzyme-dose record, energy and macronutrients intake and PERT-use (LU/g lipids) were automatically calculated by the MyCyFAPP system. Comparisons were made using linear regression models. RESULTS: The lowest quartiles for BMI and HFA were between 0 and -1SD in all the centres with no significant differences, and 33.5% of the patients had a SD-score <0 for all three parameters. The minimum energy intake recommendation was not reached by 40% of the children and mean nutrients intake values were 14%, 51% and 34% of the total energy for protein, carbohydrates and lipids respectively. When assessed per centre, reported PERT doses were in the recommended range in only 13.8% to 46.6% of the patients; from 5.6% up to 82.7% of children were above the recommended doses and 3.3% to 75% were below. CONCLUSION: Among the 6 centres, a large variability and inconsistency with new guidelines on nutrition and PERT-use was found. Our findings document the lack of a general criterion to adjust PERT and suggest the potential benefit of educational and self-managerial tools to ensure adherence to therapies, both for clinical staff and families. They will be taken into account when developing these new tools during the next stages of MyCyFAPP Project.

Estimating body composition from skinfold thicknesses and bioelectrical impedance analysis in cystic fibrosis patients.

BACKGROUND: The accuracy of body composition estimates based on skinfold thickness measurements and bioelectrical impedance analysis (BIA) is not yet adequately explored in cystic fibrosis (CF). Using DXA as reference method we verified the accuracy of these techniques and identified predictors of body composition specific for CF. METHODS: One hundred forty-two CF patients (age range: 8-31 years) underwent a DXA scan. Body fat percentage (BF%) was estimated from skinfolds, while fat free mass (FFM) from single-frequency 50 kHz BIA. RESULTS: Bland-Altman analysis showed poor intra-individual agreement between body composition data provided by DXA and BF% estimated from skinfolds or FFM estimated from BIA. The skinfolds of the upper arm were better predictors of BF% than BMI, while compared to other BIA measurements the best predictor of FFM was the R-index (Height(2)/Resistance). CONCLUSIONS: Due to poor accuracy at individual level, the estimates of body composition obtained from these techniques cannot be part of the standard nutritional assessment of CF patients until reliable CF-specific equations will become available. BMI has limited value in predicting body fatness in CF patients and should be used in combination with other predictors. Skinfolds of the upper arm and R-index are strongly related to BF% and FFM and should be tested in a large CF population to develop specific predictive equations.

Insulin secretion, nutritional status and respiratory function in cystic fibrosis patients with normal glucose tolerance.

BACKGROUND & AIMS: Impaired growth and nutritional status in CF may be related to progressive insulin deficiency before CF-Related Diabetes has established. Aim of this study was to analyse the association of circulating insulin with nutritional status and lung function in CF patients with normal glucose tolerance (NGT). METHODS: We performed OGTT in 152 consecutive CF patients aged 8-20 years: 115 of them had NGT and were included in the study. Areas under the curves (AUC) of glucose, insulin and c-peptide after 120 min were calculated. Quartiles (Q) of increasing fasting insulin (fINS-Q) and c-peptide (fCP-Q) levels were calculated in CF patients. Respiratory function parameters (FEV1, FVC), Standard Deviation Scores (SDS) of height, weight and BMI were compared between Q1 and the three higher Q. Multiple regression analysis was used to analyse the association of fasting insulin, c-peptide or OGTT derived indices with nutritional or respiratory parameters. RESULTS: Compared to patients in fINS-Q4 or fCP-Q4, those in fINS-Q1 or in fCP-Q1 respectively showed lower levels of insulin AUC or c-peptide AUC (both P < 0.0001), weight-SDS (P = 0.013, P = 0.007), BMI-SDS (P = 0.010, P = 0.002), FEV1 (P = 0.076, P = 0.013) and FVC (P = 0.101, P = 0.009). Age- and gender-adjusted regression analysis showed significant associations of fINS and fCP with SDS of BMI (P = 0.023 and P = 0.001 respectively), fCP was significant associated with FEV1 (P = 0.01). AUC insulin/AUC glucose ratio (P < 0.0001) and AUC c-peptide/AUC glucose ratio (P = 0.0001) were significantly associated with FEV1. CONCLUSIONS: Insulin deficiency in CF patients with NGT has a significant impact on clinical outcomes.