Longitudinal body composition assessment in healthy term-born infants until 2 years of age using ADP and DXA with vacuum cushion.

OBJECTIVES

Accelerated gain in fat mass (FM) in early life increases the risk for adult diseases. Longitudinal data on infant body composition are crucial for clinical and research use, but very difficult to obtain due to limited measurement tools and unsuccessful measurements between age 6-24 months. We compared FM% by dual-energy X-ray absorptiometry (DXA), with cushion to reduce movement artifacts, with FM% by air-displacement plethysmography (ADP) and evaluated the reliability of this cushion during DXA by comparing FM% with and without cushion. Subsequently, we constructed sex-specific longitudinal body composition charts from 1-24 months.

METHODS

In 692 healthy, term-born infants (Sophia Pluto Cohort), FM% was measured by ADP from 1-6 months and DXA with cushion from 6-24 months. At 6 months, FM% was measured in triplicate by ADP and DXA with and without cushion(n = 278), later on in smaller numbers.

RESULTS

At 6 months, mean FM% by DXA with cushion was 24.1 and by ADP 25.0, mean difference of 0.9% (Bland-Altman p = 0.321, no proportional bias). Mean FM% by DXA without cushion was 12.5% higher compared to ADP (Bland-Altman p < 0.001). DXA without cushion showed higher mean FM% compared to DXA with cushion (+11.6%, p < 0.001) at 6 months. Longitudinally, FM% increased between 1-6 months and decreased from 6-24 months(both p < 0.001).

CONCLUSIONS

In infants, DXA scan with cushion limits movement artifacts and shows reliable FM%, comparable to ADP. This allowed us to construct longitudinal body composition charts until 24 months. Our study shows that FM% increases from 1-6 months and gradually declines until 24 months.