Prospective cohort studies using hydrolysed formulas for allergy prevention in atopy-prone newborns: a systematic review

The aim of this study is to give a systematic overview on publications having investigated the allergy preventive effect of extensively and/or partially hydrolysed infant formulas. Publications were searched by several strategies. Inclusion criteria were: prospective cohort study, randomisation, family history of atopy of the subjects, follow-up for at least the 1st year of life. Studies were described systematically as to methods, study participants, interventions and co-interventions, and study outcomes. The methodological quality was judged according to an instrument assessing the reduction of bias (score between 0 and 7 points). Data of studies having examined partial hydrolysates are presented as odds ratios. Of 16 studies found, 10 fulfilled the inclusion criteria. Study designs showed considerable differences as to methods, intervention and co-intervention procedures and definition of outcomes. Methodological quality varied between 0 and 6 points. The comparison of exclusively test- and control formula-fed groups showed a uniform tendency towards allergy protection in studies with partial hydrolysates. Study results on the effect of extensive hydrolysates were not comparable because of major differences in study designs. Conclusion More well-designed studies with an adequate statistical power are needed to compare the allergy preventive effect of partially and extensively hydrolysed formulas with a standard infant formula. Received: 17 May 2000 / Accepted: 30 January 2001