Survival-Adjusted FEV1 and BMI Percentiles for Patients with Cystic Fibrosis before the Era of Triple CFTR Modulator Therapy in Germany.

BACKGROUND: Pulmonary disease is the major cause for morbidity and mortality in cystic fibrosis (CF). In CF, forced expiratory volume in 1 s (FEV1) referenced against a healthy population (FEV1%predicted) and body mass index (BMI) do not allow for the comparison of disease severity across age and gender. OBJECTIVES: We aimed to determine updated FEV1 and BMI percentiles for patients with CF and to study their dependence on mortality attrition. METHODS: Age- and height-adjusted FEV1 and BMI percentiles for CF patients aged 6-50 years were calculated from 4,947 patients of the German CF Registry for the period 2016-2019 utilizing quantile regression and a Generalized Additive Model for Location, Scale and Shape (GAMLSS). Further, survival-adjusted percentiles were estimated. RESULTS: In patients with CF, FEV1 increased throughout childhood until maximal median values at 16 years in females (2.46 L) and 18 years in males (3.27 L). During adulthood, FEV1 decreased substantially. At 17 years of age, the 25th BMI percentile of patients with CF (females 18.50 and males 18.15 kg/m2) was below the 10th BMI percentile of the German reference cohort. From the age of 20 years, survival (96.3%) decreased tremendously. At 50 years of age (survival 15.0%), the 50th CF-specific FEV1 or BMI percentile among the survivors corresponded to the 92.5th percentile among the total CF birth cohort. CONCLUSIONS: Continuously updated disease-specific FEV1 and BMI percentiles with correction for survival may serve as age-independent measure of disease severity in CF (accessible via https://cfpercentiles.statup.solutions).

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.

Reference Values Matter: Fewer Patients With Malnutrition Using American Compared to More Recent German Growth Charts.

ABSTRACT: Reference values are important for patient care as well as for comparisons between different centers or countries. We investigated two anthropometric reference datasets, the US Centers for Disease Control (CDC) growth charts and the German Health Interview and Examination Survey for Children and Adolescents Study (KiGGS) percentiles, which were established in Germany between 2003 and 2006. A smaller proportion of children with cystic fibrosis had decreased z scores <-2 with CDC (5.0% for weight and 3.0% for height) compared to KiGGS (7.4% for weight and 6.3% for height) values (P < 0.0001). Median z scores were higher using the CDC reference data. Thus, the choice of growth reference is important, may influence clinical management and must be considered when comparing the outcomes of different institutions.