Mallet 1992.

Methods	Single‐centre randomised controlled trial in France.
Participants	Inclusion criteria: 177 infants with immediate family history of allergic disease. Allergic disease score used.
Interventions	Sole or supplementary formula feeding for at least 4 months Treatment (n = 92): extensively hydrolysed casein formula (Pregestemil, Mead Johnson). Control (n = 85): CMF (Galliazyme, Gallia, France). No co‐interventions.
Outcomes	Primary outcome(s): allergic disease. Other outcomes: clinician assessment for allergic disease. Eczema and IgE assessed at 4 months; eczema, asthma and CMA assessed at 1, 2 and 4 years. Definitions Atopic eczema: graded as mild (< 4 patches), moderate or severe. Asthmatic bronchitis: grade 1 (2 to 4 occurrences per year) and grade 2 (> 4 per year). CMA: confirmed by type 1 reagin allergy (specific IgE RAST) or malabsorption.
Notes	Excess losses at all time periods except 4 months (infant allergic disease incidence). Trial of supplemental or sole extensively hydrolysed casein formula vs CMF. Results for only 4 months included (infant allergic disease incidence). Conflict of interest: Mead Johnson and Gallia supplied formula.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Infants randomised postnatally; method not reported.
Allocation concealment (selection bias)	Unclear risk	Details not reported.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The study design was not blinded.... and formulas were easily distinguishable by taste and smell.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Both parents and paediatricians knew which formula was fed to the infant.
Incomplete outcome data (attrition bias) All outcomes	High risk	HF group (n = 92): 5 (5%) at 4 months, 21 (23%) at 1 year, 14 (15%) at 2 years, 22 (24%) at 4 years. CMF group (n = 85): 7 (8%) at 4 months, 32 (38%) at 1 year, 24 (28%) at 2 years, 31 (36%) at 4 years. Three children failed to follow diet prescriptions and were excluded. No withdrawal seemed to be motivated by any abnormality linked to cow's milk intolerance.
Selective reporting (reporting bias)	High risk	Quote: "Aim of assessing the allergy prevention effects". Reported multiple allergic disease outcomes, grades of severity and time points.
Other bias	Low risk	Well‐balanced groups after allocation.