Despite major improvements in clinical and nutritional care, final height remained impaired in boys with cystic fibrosis (CF) who experienced a rapid increase in body mass index (BMI) between the ages of 1 and 6, according to a study published in Pediatric Pulmonology.

This longitudinal, retrospective study examined a cohort of 57 patients (30 boys and 27 girls) with CF born between 1997 and 2001 to determine if final height was affected by BMI, BMI increase, CF-related diabetes, and pulmonary function. Participants’ weight and height were recorded every year from ages 0.5 to 10, and biannually thereafter, until the age of 18. Measurements were converted to height-for-age-adjusted-for-target-height (HFA-TH) and BMI-for-age z-scores, and the Pearson’s correlation and independent t-tests were used to perform analyses.

HFA-TH and BMI-for-age z-scores for both boys and girls were significantly lower in the first year of life, then rapidly increased until the age of 11 for boys and the age of 8 for girls. The HFA-TH z-scores of boys declined during puberty, with a subsequent final height that was significantly impaired (z-score, -0.56; n=30, standard deviation [SD]; 0.81; P =.001). The HFA-TH z-scores of girls briefly declined after age 8, then increased to a z-score of -0.21 (n=27; SD, 0.87) at age 18, which is only slightly lower than the national average (P =.22). The presence of CF-related diabetes and pulmonary function were not associated with final height; however, a rapid increase in BMI between ages 1 and 6 was negatively associated with final height in girls (n=25; r=-0.466; P =.019) and boys (n=29; r=-0.420; P =.023).

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Study investigators concluded that associations with rapid early BMI increase and impair final height and “that final height remains impaired in boys with CF despite major improvements in nutritional and clinical care. Future research should investigate the role of early childhood BMI increase in growth retardation in greater depth and detail: this may yield important new knowledge for the further refinement of future nutritional strategies.”

Reference

Hak SF, Arets HGM, van derEnt CK, van derKamp HJ. Rapid early increase in BMI is associated with impaired longitudinal growth in children with cystic fibrosis [published online April 22, 2019]. Pediatr Pulmonol. doi:10.1002/ppul.24343