Table 1 Demographic and clinical characteristics of the psychiatric intervention and unexposed groups
All patientsPropensity-matched patients
Unexposed group (n=16 529)Psychiatric intervention group (n=13 035)Absolute standardised differenceUnexposed group (n=7938)Psychiatric intervention group (n=7938)Absolute standardised difference
n%n%n%n%
Female10 94466.2931071.411.2562070.8557670.21.3
Age, years
 12–1910446.38846.82.05506.95236.61.2
 20–29340120.6318124.49.1197824.9187723.63.0
 30–39329319.9331525.413.2195524.6193424.40.5
 40–49265116.0256419.79.7155919.6155819.60.0
 50–5914688.9134310.34.87869.979110.00.3
 60–6913898.48746.76.45306.75677.11.6
 70–7914418.75484.218.43584.64005.01.9
 80–8914428.72892.228.91982.52543.24.2
 ≥904002.4370.318.3240.3340.41.7
Toxic agent
 Non-opioid analgesics, anti-pyretics and anti-rheumatics6513.97305.68.03834.83654.60.9
 Anti-epileptic, sedative-hypnotic and anti-Parkinsonism drugs468528.3410931.57.0242330.5246931.11.3
 Other psychotropic drugs11727.111869.17.37018.86978.80.0
 Other drugs211312.82732.141.61431.82342.97.3
 Unspecified drugs790847.8673751.77.8428854.0417352.62.8
Classification of mental disorder
 Schizophrenia13948.4221017.026.0113314.3115414.50.6
 Mood disorders384523.3548442.140.9300637.9307038.71.6
 Organic mental disorders2601.61781.41.61141.41271.61.6
 Mental disorders due to psychoactive substance use4512.73512.70.02603.32713.40.6
 Disorders of personality and behaviour2611.64613.512.12102.62172.70.6
 Other mental disorder11907.2204215.726.9101212.799012.50.6
 Not known912855.2230917.784.6220327.8210926.62.7
Level of consciousness on admission
 Alert529932.1290922.322.2198325.0194924.60.9
 Dull374622.7328025.25.9188623.8191924.20.9
 Somnolence341620.7296322.74.9184623.3185023.30.0
 Coma406824.6388329.811.7222328.0222028.00.0
Charlson comorbidity index
 012 25174.111 20085.929.8677585.3664083.64.7
 1252415.3135210.414.785910.892911.72.8
 29946.03272.517.42152.72473.12.4
 ≥37604.61561.220.4891.11221.53.5
Tracheal intubation10196.2213016.332.47879.981610.31.3
Haemodialysis2031.22491.95.7971.21111.41.8
Academic hospital553233.5632848.530.9326941.2324840.90.6
Hospital volume groups, per year
 Low (≤38)667340.4324024.933.5249131.4244430.81.3
 Medium (39–84)552933.5421632.32.6265133.4268833.91.1
 High (≥85)432726.2557942.835.5279635.2280635.30.2
Fiscal year of discharge
 2010582535.2329025.221.9245430.9241930.50.9
 2011569334.4500238.48.3295937.3294937.20.2
 2012501130.3474336.413.0252531.8257032.41.3