Survival risk ratios for ICD-10-AM injury diagnosis classifications for children

The survival risk ratios (SRRs) were calculated using linked
hospitalisation and mortality data from Australia. Hospital admissions was obtained from each
Health Department or the Australian Institute of Health and Welfare and
included all injury-related admissions identified using a principal diagnosis
of injury (ICD-10-AM: S00-T89) of children aged ≤16 years during 1 July 2002 to
30 June 2012. In the Australian Capital
Territory (ACT) data were only available from 1 July 2004. Mortality data was obtained from the National
Death Index. Hospitalisation and
mortality data were probabilistic linked by the Australian Institute of Health
and Welfare Data Linkage Unit. There
were an estimated population of 4.5 million children aged ≤16 years in
Australia.

The SRRs were calculated for each injury diagnosis. A SRR
represents the ratio of the number of individuals with each injury diagnosis
who did not die to the total number of individuals with the injury
diagnosis. The SRRs can be used to
estimate injury severity (i.e. the International Classification of Injury
Severity Score: ICISS). The ICISS is
calculated by applying the SRRs to each injury diagnosis code in your
data. A SRR represents the ratio of the number of children with each
injury diagnosis who did not die to the total number of children with the
injury diagnosis. There are two methods commonly used to estimate ICISS
values: (i) multiplicative-injury ICISS where ICISS is the product of all
SRRs for each of the child’s injuries; and (ii) single worst-injury, where
ICISS only includes the worst-injury (i.e. the injury diagnosis with the lowest
SRR) as the single worst-injury.