APPENDIX

Web Table 1 Hierarchy of ICD 10 diagnostic codes used to classify cause of injury *

Description / ICD-10 Code groups / Prevalence** / Within-class prevalence
MALTREATMENT-SYNDROME CODES / 0.9%
Maltreatment syndromes / T74 / 62.4%
Perpetrator of neglect and other maltreatment syndromes / Y06, Y07 / 37.6
MALTREATMENT-RELATED FEATURES
Assault / 0.3%
Excludes assault by poisoning (X85 - X90)
Assault by bodily force / Y04, Y05 / 48.6%
Other types of assault / X91 - Y03, Y08 - Y09 / 51.4
Undetermined cause / 0.8%
Events of undetermined intent / Y20 - Y34 / 44.7%
Blood -alcohol and blood-drug tests / Z04.0 / 0.2
Examination and observation following other inflicted injury / Z04.5 / 12.4
Examination and observation for other reasons: request for expert evidence / Z04.8 / 42.7
Adverse social circumstances / 0.7%
Problems related to social environment / Z60 / 17.1%
Problems related to negative life events in childhood / Z61 / 17
Other problems related to upbringing / Z62 / 14
Other problems related to primary support group / Z63 / 31.6
Problems related to lifestyle / Z72 / 0.5
Problems related to care-provider dependency / Z74 / 1.1
Health supervision and care of foundling / Z76.1 / 0.1
Health supervision and care of other healthy infant and child / Z76.2 / 3
Family history of mental and behavioural disorders / Z81 / 7.6
Personal history of other mental and behavioural disorders / Z86.5 / 0.1
Personal history of other physical trauma / Z91.6 / 4.6
Personal history of other specified risk-factors, not elsewhere classified / Z91.8 / 3.2
OTHER CAUSES
Ingestion of toxic substances or self harm / 13.4%
Accidental poisoning / X40 - X49 / 93.2%
Intentional self-harm with toxic substances / X60 - X69 / 1.8
Assault by toxic substances / X85 - X90 / 0.1
Events of undetermined intent, poisoning / Y10 - Y19 / 0.3
Observation for suspected toxic effect from ingested substance / Z03.6 / 4.6
Self-harm (excludes self-harm by poisoning) / X70-X84 / 0.0
Accidents / 68.8%
Road traffic accidents / V01 - V99 / 4.6%
Other external cause of accidental injury / W00 - X39, X50 - X59 / 95.4
Co-morbidities or complications / 10.0%
Co-morbidities / 58.8%
Other diagnostic codes not considered above and different to injury codes S & T / Blocks A - R of the ICD-10
Complications or sequelae of other events / 41.2%
Injury due to or during legal intervention / Y35-Y36 / (0.0%)
Complications of medical and surgical care / Y40-Y84 / (95.3)
Sequelae of external cause of morbidity and mortality / Y85-Y89 / (4.4)
Supplementary factors of external causes of morbidity and mortality / Y90-Y98 / (0.3)
No explanation / 5.1%
No additional codes to injury diagnoses (single or multiple)

* Codes recorded in up to 20 diagnostic fields (14 before 2007 and seven before 2002) for each hospital episode. Categories are exclusive and arranged in a descending hierarchy.

** Prevalence of category within all under 5 year-old injury admissions


Box: Clinical examples

One child had maltreatment-syndrome (T74.1) and codes for fractured skull, other fractures and superficial injuries. A second child had a code for undetermined cause (Y31.9), a code for an unspecified problem related to the social environment and codes for fracture of the femur and for a fall. A third child had codes reflecting problems related to the primary support group (grouped as adverse social circumstances in our classification -Z63.8) and codes for retinal haemorrhage and intracranial injury.