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

OBJECTIVE: This study aimed to investigate the effectiveness of proportionate universalism intervention to reduce the slope of the nutritional social gradient in adolescents. STUDY DESIGN: A mixed (experimental and quasi-experimental) multicentre trial. METHODS: 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. RESULTS: The inclusion data confirmed a weight social gradient expressed by a significant BMIz linear regression coefficient (ß = -0.09 [-0.14 to -0.04], P < 0.0001). The higher the social class, the lower the BMIz. The 1-year BMIz linear regression coefficient was -0.07 [-0.12 to -0.02], corresponding to a significant weight social gradient reduction of 23.3% (ß = 0.021 [0.001 to 0.041]; P = 0.04). Consistent results were found for other nutritional outcomes. CONCLUSIONS: PRALIMAP-INÈS shows that proportionate universalism intervention is effective to reduce the adolescents' nutritional social gradient and suggests that equitable health programmes and policies are a realistic goal.