Utility of Mid-Upper Arm Circumference in Diagnosing Malnutrition in Children With Cystic Fibrosis

Background Standardized diagnostic indicators for malnutrition using growth percentilez-scores (weight for length or body mass index [BMI]) and mid-upper arm circumference (MUAC)z-scores are being used in clinical practice; however, their application to the pediatric cystic fibrosis (CF) population is not well described. In this study, we aim to compare growth percentilez-scores and MUACz-scores in diagnosing and classifying malnutrition in children with CF and assess the relationship between their degree of malnourishment and corresponding pulmonary function tests (PFTs). Methods In this retrospective observational outpatient study of 49 pediatric CF patients, data were collected on baseline characteristics, anthropometrics, and PFTs over 12 months. Agreement in malnutrition diagnoses was quantified by Cohen kappa statistics. Pearson test assessed the correlation between MUAC and BMIz-scores as well as PFTs and anthropometrics. Serial anthropometrics and PFTs were obtained and compared for a subset of patients (n = 28). Results Growth percentile and MUACz-scores were positively correlated in diagnosing malnutrition (Pearson correlationr= 0.87), but MUACz-scores identified more patients as malnourished compared with growth percentilez-scores (49% vs 12%, Cohen kappa of 0.22 [95% CI, 0.04-0.40]). There was no significant relationship between anthropometrics and PFTs. MUACz-scores increased significantly over time, but BMIz-scores did not show this trend. Conclusions Our small-scale data suggest a promising role for MUACz-scores in classifying malnutrition and in measuring changes in nutrition status over time in pediatric CF.