Suicidal behavior was defined as a record of death by suicide (identified through the Cause of Death Register) or lifetime suicide attempts (hospital admissions or outpatient consultations in specialized care due to suicide attempts identified through the NPR). To avoid underestimation of suicidal behavior rates and be consistent with recent suicide research,25, 26 we included both certain and undetermined causes in our definitions of death by suicide and attempted suicide as follows: ‘suicide and self-inflicted injury’ (ICD-8 and ICD-9 codes E950-E959); ‘intentional self-harm’ (ICD-10 codes X60-X84); ‘injury undetermined whether accidental or purposely inflicted’ (ICD-8 and ICD-9 codes E980-E989) and ‘events of undetermined intent’ (ICD-10 codes Y10-Y34). Methods of death by suicide and attempted suicide were classified according to ICD grouping codes (for specific ICD codes, see Supplementary Material). Further, methods were classified into self-poisoning (poisoning) and self-injury (remaining methods).27
