Arm muscle area for the longitudinal assessment of nutritional status in paediatric patients with cystic fibrosis - A single centre experience.

BACKGROUND:In cystic fibrosis, adequate nutrition contributes to good long-term prognosis. A body mass index (BMI) at or above the 50th percentile for age and sex in all children has been recommended. As researchers have described a depletion of fat-free mass despite normal BMI, longitudinal studies using more sensitive nutritional parameters are warranted. We evaluated anthropometric measurements in an attempt to identify early indicators of deteriorating nutritional status in our paediatric cohort. METHODS:We analysed datasets from children and adolescents between 2 and 17.9 years with at least two entries for triceps skinfold thickness and upper arm circumference in our patient database between January 1995 and December 2018. Arm muscle area (AMA) was calculated, and all values were expressed as z-scores from CDC growth charts. RESULTS:A total of 4,862 encounters from 161 paediatric patients (78 girls) were available, representing a median number of 28 visits during a median follow-up of 8.1 years per patient. Linear mixed effects models revealed relatively stable courses for weight, height, BMI and skinfold thickness up to adulthood. AMA was the only parameter which declined slightly (r = -0.036), particularly in boys. Kaplan-Meier-analyses showed that AMA was the earliest parameter to decrease below -1 z-score between 6 and 18 years. CONCLUSIONS:The present data suggest that compared with weight or BMI, AMA could serve as an earlier indicator of a deteriorating nutritional status. The benefit of assessing skinfold thickness and arm circumference routinely and calculating AMA from these measurements should be evaluated in large, prospective, multi-centre studies.