  The Injury Severity Score (ISS) is a standard aggregate indicator of the
overall severity of multiple injuries to the human body. This score is
calculated by summing the squares of the three highest values of the
Abbreviated Injury Scale (AIS) grades across six body regions of a trauma
victim. Despite its widespread usage over the past four decades, little is
known in the (mostly medical) literature on the subject about the axiomatic and
statistical properties of this quadratic aggregation score. To bridge this gap,
the present paper studies the ISS from the perspective of recent advances in
decision science. We demonstrate some statistical and axiomatic properties of
the ISS as a multicrtieria aggregation procedure. Our study highlights some
unintended, undesirable properties that stem from arbitrary choices in its
design and that call lead to bias in its use as a patient triage criterion.
