Table 1

Predictor inputs for frailty risk prediction model (independent variables)

NameTime spanDescriptionComments
AgeCurrent spellThe startage field from HES
SexCurrent spellThe sex field from HES
Admission sourceCurrent spellThe admiSorc field from HES
Charlson (historic)24-month historic averageCalculated per spell, using all diagnoses from all episodes and then averaged. Excludes the current spell 
Charlson (current)Current spellCalculated using diagnoses in positions 2–20 from all episodes in the spell
Anxiety and depression24-month historic binary indicatorA binary flag indicating whether a relevant diagnosis has been received during any inpatient spell in the past 24 monthsSenility, dementia and delirium merged to form the cognitive impairment indicator because of changes in coding over time
Cognitive impairment
Falls and fracture
Mobility problems
Pressure ulcers
Number of emergency admissions12-month historic countThe number of emergency admission spells in the previous 12 months, excluding the current spellNormalised
Days since last emergency admission24-month historicThe number of days since the patient's last discharge from an emergency admissionNormalised. Default value used when the patient has not had an emergency admission in the previous 24 months
  • HES, Hospital Episode Statistics.