Objective: The aim of the study was to compare 3 international growth references and explore their differences in assessing growth in Greek school-aged patients with cystic fibrosis (CF).
Methods: Sample included 114 patients (50 boys, age 11.5 ± 3.9 years), provided care at Aghia Sofia Children's Hospital, Greece. Anthropometrics and predicted forced expiratory volume in 1 second (FEV1%) were measured. Body mass index (BMI) and height z scores were computed according to the Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), and International Obesity Task Force (IOTF) references. Agreement between methods was analyzed with kappa statistics, repeated-measures analysis of variance, and Bland-Altman analysis. The relationship between FEV1% and BMI was explored with linear regression.
Results: Mean CDC BMI z score was the lowest (0.06 ± 1.08), followed by WHO (0.17 ± 1.14) and IOTF (0.35 ± 1.05) (P ≤ 0.001 for all). The CDC and WHO growth references highly agreed for most weight status strata and stunting; all other comparisons produced lower agreements. Except for CDC and IOTF BMI z scores, all other comparisons produced wide levels of agreement and proportional bias. CDC reference classified more children as attaining low or normal weight, against WHO or IOTF (P ≤ 0.001 for all). Lowest prevalence of ideal and excess weight was recorded by CDC, compared to all other standards (P ≤ 0.001 for all). All BMI z scores provided moderate associations with FEV1%.
Conclusion: Large variations across weight status classification were present when employing 3 growth standards in school-aged patients . Given than BMI z-scores from all references provided comparable associations with pulmonary function, our data indicate that no studied reference is better than others in assessing growth in CF.