Proportionate universalism intervention is effective for tackling nutritional social gradient in adolescents: the PRALIMAP-INÈS mixed randomised trial

This study aimed to investigate the effectiveness of proportionate universalism intervention to reduce the slope of the nutritional social gradient in adolescents. A mixed (experimental and quasi-experimental) multicentre trial. Data from 985 adolescents of the PRALIMAP-INÈS trial (North-eastern France, 2012–2015) were analysed. For this, adolescents were split into five social classes according to the Family Affluence Scale: Highly Less Advantaged (H.L.Ad; n = 33), Less Advantaged (L.Ad; n = 155), Intermediate (Int; n = 404), Advantaged (Ad; n = 324) and Highly Advantaged (H.Ad; n = 69). The overweight care management was a standard care for all and a strengthened one adapted to the social class of adolescents. The main outcome was the 1-year change of the body mass index z-score (BMIz) slope. Other nutritional outcomes were BMI, ΔBMIp95 (BMI minus 95th percentile of the WHO reference), %BMIp95 (percent of 95th percentile of the WHO reference), leisure-time sport, consumption of fruits and vegetables and consumption of sugary foods and drinks. The inclusion data confirmed a weight social gradient expressed by a significant BMIz linear regression coefficient (β = −0.09 [−0.14 to −0.04], P