Background: Over the last 20 years, hydrolyzed rice protein formulas (HRFs) have gradually become available on the market. The present real-world study aimed to understand in which situations HRFs, thickened (T) or un-thickened (UT), are prescribed and to assess the acceptability and digestive tolerance of such formulas.Method: In this multicentric, prospective, real-world study, healthcare professionals proposed to parents of non-breast-fed, younger than 3 months old infants to participate as soon as they intended to recommend an HRF. Two formulas (Novalac, United Pharmaceuticals, France) differing mainly by the presence or absence of a fiber-based thickening complex were proposed.Parents were asked to feed their child exclusively with the study formula until the next visit planned after one month and to complete the Infant Gastrointestinal Symptom Questionnaire (IGSQ) after 2 weeks. Monthly follow-up visits were planned for up to 6 months. At each visit, the investigator performed a clinical exam and reported several data (such as anthropometric, digestive, and allergic symptoms using the Cow's Milk-related Symptom Score, CoMiSSTM).Results: A total of 155 children (54.2 % boys; 6.1 ± 3.8 weeks old) were included by 8 pediatricians; 58% (90/155) were fed the UT-RF; 144 were fed one study-HRF during 3 months and 79 during 6 months.Both formulas were recommended mostly for cow's milk allergy (CMA), confirmed or suspected (65.1%). The fact that the HRF is lactose free was mentioned as a reason in 26% of all prescriptions, isolated Gastro-intestinal (GI) disorders in 25% and parent’s request in 19%.The IGSQ score was significantly higher at baseline in infants receiving the T-RF versus those receiving the UT-RF (median (mean± SD): 43 (43.8 ± 8.8) vs 41 (39.2 ± 7.8), p <0.01). Within two weeks, the IGSQ decreased significantly (global : -7 (-8.8±9.2), T-RF :-8 (10.3±11.2); UT-RF : -7 (-7.8±7.4); p<0.001) and at each visit with both HRFs. Over 90% of infants experienced regurgitation at the time of inclusion, with a significantly higher proportion among those receiving T-RF versus UT-RF. (96.8% vs 87.1%, p<0.05). The number of regurgitations and their severity (evaluated through Vandenplas’ score) was decreased (respectively -1 (-1.3±2.1) and -1(-0.9±1.2)) within day 14.At baseline, the CoMiSS TM score was significantly higher in the group of infants with CMA (proven or suspected; 10 (11.9 ± 5.8)) than in the group of infants who had been prescribed HRF for another reason (7 (8.1 ± 4.8); p <0.001). The CoMiSS TM decreased significantly in those 2 sub-populations (-6 (-6.9±5.7) and -3(-3.8±5.1), respectively) by day 30Mean weight-for-age, length-for-age and head circumference-for-age z-score were within normal range all along the study and significantly increased within the 6 months study duration.Conclusion: In daily practice, HRFs are recommended most frequently in case of CMA, confirmed or suspected but the presence of GI disorders and the need of a lactose free formula are both mentioned in 1 out of 4 prescriptions. Feeding HRFs formulas ensures proper growth while reducing intestinal and allergic symptoms (evaluated through IGSQ and CoMiSS).
