Strength and Muscle Related Outcomes for Nutrition and Lung Function in CF (STRONG-CF)

PROTOCOL SUMMARY Nutrition is a lifelong cornerstone of cystic fibrosis (CF). Starting at a very early age and continuing into adulthood, many people with CF struggle to maintain adequate nutrition. This can be quite stressful, both for people with CF and their family and caregivers. Ultimately, significant interventions, such as feeding tubes, are often needed to meet nutritional needs. As lung disease advances, nutrition becomes even more important, with nutritional derangements (“malnutrition”) impacting both survival and eligibility for lung transplantation. Despite emphasis on nutrition, we have very little evidence (beyond observational, cross-sectional studies) for what it means to be “nourished” versus “malnourished.” At the other end of the nutrition spectrum, there has been an increase in the prevalence of overweight and obesity in the CF population, particularly with the advent of highly effective modulator therapies (HEMT). The clinical consequences of overweight and/or obesity in CF are as yet unknown. Currently, there are two main foci of nutrition within the CF community: (a) weight-to-height measurements such as growth curves and body mass index (BMI), and (b) laboratory values for micronutrients. These items are easily measured and translatable into specific goals, but there is a paucity of evidence backing our emphasis on these foci. Other markers of nutrition status, including body composition (muscle versus fat) and assessment of related disorders (frailty, sarcopenia), could be even more important regarding both outcomes as well as markers for interventions. The overarching goal of this study is to examine multiple markers of anthropometrics, body composition, sarcopenia, and frailty and compare them to dual energy X-ray absorptiometry (DXA) output, which is considered the current clinical gold-standard tool to measure body composition. A robust analysis will be done using both cross-sectional and longitudinal data to characterize the performance of these biomarkers over time and establish their relationship with DXA output. The results of this study will not only provide detailed data regarding the nutrition and body composition within this CF population, but also provide a baseline evaluation for use of these biomarkers for future studies including evaluation of nutritional interventions. Further, this study will include psychosocial and other patient-reported outcomes and medical contributors (such as hyperglycemia) to understand their contributions to nutritional failure in the adult advanced lung disease population, which will also inform future interventional trials. Lastly, this study will evaluate both established and emerging nutritional and body composition parameters and link them to clinical outcomes in adults with CF across the spectrum of pulmonary function.