Table 1

Baseline characteristics of the study population

General demographicsDevelopment sample
N=37 523
Validation sample
N=15 649
Age in years, median (IQR)*32.221.4–48.932.521.4–49.1
Individuals under 16 years22245.98645.5
Sex, female*20 56154.8868555.5
Substance misuse
Current or lifetime alcohol use disorder, excluding alcohol intoxication*725719.3302519.3
Current or lifetime drug use disorder (including drug intoxication)*838422.3367223.5
Alcohol intoxication at index14163.88155.2
Living status†
Living with other adults14 15137.7569736.4
Living with children15 49341.3649441.5
Treatment in the past 3 months
Any psychotropic medication20 88855.7953760.9
Antidepressant treatment12 52733.4600938.4
Antipsychotic treatment425911.4183411.7
Mood-stabiliser treatment6771.83102.0
Physical health problems
New cancer diagnosis4111.11491.0
History of self-harm
Method of index self-harm event
 Any psychotropic medication overdose13603.65393.4
 Hanging, strangulation or suffocation3080.81501.0
Lifetime history of self-harm prior to index*11 27730.1537234.3
History of self-harm in the past 12 months prior to index*428111.4199412.7
Number of lifetime prior self-harm episodes, including the index self-harm event
 1–2 episodes31 74084.612 87982.3
 3+ episodes578315.4277017.7
Overnight admission16 99145.3753148.1
Time between episodes ≤1 month19295.18385.4
Mental health in the past 12 months
Any psychiatric disorder (except substance use disorders)16 47243.9728146.5
Serious psychiatric disorder30068.013058.3
Criminal/violence/legal issues
Lifetime criminal record for any crime13 45135.9597438.2
Criminal record for any crime in past 12 months381610.2180911.6
Lifetime arrest history for any crime15 06840.2650641.6
Arrest history for any crime in past 12 months641617.1281818.0
Lifetime criminal record for violent crime572915.3257616.5
Criminal record for violent crime in past 12 months8972.44162.7
Lifetime arrest history for violent crime540214.4226614.5
Arrest history for violent crime in the past 12 months21415.78725.6
Family history
Family history of suicide11183.05303.4
Family history of any psychiatric disorder15 11240.3650341.6
  • Values are all numbers and percentages, except for age for which median years and IQR are reported. Criminal arrest refers to being charged for an offence.

  • *Core factor, kept in the final model independently of its statistical significance or predictive strength.

  • †Living status information was missing for 641 (2%) individuals in the development sample and 199 (1%) in the validation sample. Individuals under 16 years old with missing living status were reclassified as ‘living with other adults’ (2049 (92%) of the under 16s in the development sample; 815 (94%) in the validation sample). Of those with missing living status, two individuals died from suicide more than 12 months since index in the development sample, zero in the validation sample. For variables psychiatric treatment, mental health, family history, new cancer diagnosis and self-harm method, when there was no information, it was assumed to indicate the variable did not occur rather than a missing value.

  • ‡It was possible for an individual’s index self-harm event to be coded under more than one of the methods listed. The majority of individuals not included in any of the listed categories had either non-psychotropic medicine overdose or an unspecified method of index self-harm. Drowning was too rare to enter into the multivariable model.