Houwing 2003.

Methods	Randomised clinical trial, the Netherlands
Participants	103 hospitalised adults admitted for hip fracture and PO‐score > 8, at nutritional risk due to being frail elderly Male:Female = 19:84 Mean age = 81 years Exclusion criteria: Terminal care, metastatic hip fracture, insulin‐dependent diabetes, renal disease (creatinine > 176 mmol/l), hepatic disease, morbid obesity (BMI > 40), need for therapeutic diet incompatible with supplementation, and pregnancy or lactating
Interventions	Experimental group: 400 ml high‐protein nutritional supplement enriched with arginine, zinc and antioxidants with energy: 500 kcal, 40 g of protein (n = 51) Control group: 400 ml placebo (non‐caloric, water‐based drink only sweeteners, colourants and flavourings) Look and taste of the supplements were not exactly identical, but were given in similar, blinded packages to mask the differences. Participants received 400 ml daily between regular meals of either the study or placebo supplement starting immediately postoperatively for a period of 4 weeks or until discharge. (n = 52) Co‐intervention: regular diet (oral)
Outcomes	Incidence of pressure ulcers and maximum wound size
Study dates	Between April 1998 and December 1999
Notes	We contacted the authors by Linkedin. We received an initial response but no further response.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The control group received a placebo drink.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It was unclear how the outcome assessment was performed.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were below 5% dropouts and participants with incomplete data.
Selective reporting (reporting bias)	Unclear risk	No protocol could be obtained, and the trial did not report all‐cause mortality or serious adverse events.
For‐profit bias	High risk	The trial was funded by a company that might have conflict of interest (Numico).
Other bias	Low risk	The trial appeared to be free of other components that could put it at risk of bias.