The attached study entitled Review of Nutrition and Mortality Indicators for the IPC - Reference Levels and Decision-making was commissioned by the SCN Task Force on Assessment, Monitoring and Evaluation (TF/AME) and the Integrated Food Security Phase Classification (IPC) Global Partnership.
Here is an official guideline from the United Nations Standing Committee on Nutrition (SCN) on the assessment of the nutritional status of adults in emergency-affected populations. This guidelines reviews the use of BMI, MUAC, clinical, and mixed indicator methods.
The Task Force on Assessment, Monitoring, and Evaluation of the United Nations System Standing committee on Nutrition has released a fact sheet on MUAC which you can download here.
A Joint statement by the World Health Organization, the World Food Programme, the United Nations System Standing Committee on Nutrition and the United Nations Children’s Fund has endorsed the use of MUAC for identifying severe acute malnutrition in children.