Repeated poisonings in Denmark – a nationwide study

Figures & data

Figure 1. Age histogram highlighting the overrepresentation of patients with repeat poisoning episodes aged 15–30 years.

Table 1. Patient characteristics.

	Danish Poison Information Centre	Danish National Patient Registry
Patients, total n	137	995
Gender
Female	113 (82.5%)	660 (66.3%)
Age, y
Median (IQR)	24.7 (19.4–37.3)	29.5 (20.4−41.3)
<10 years	n = 7 (5.1%)	n = 10 (1.0%)
Hospital contacts with poisoning
Median (IQR)	13.0 (7.0–21.5)	14 (10–22)
Psychiatric comorbidity^a
Addictive disorders	50 (36.5%)	557 (56.0%)
Schizophreniform disorders	62 (45.3%)	427 (42.9%)
Affective disorders	96 (70.1%)	542 (54.5%)
Anxiety disorders	22 (16.1%)	120 (12.1%)
Personality disorders	102 (74.5%)	667 (67.0%)
Pervasive mental developmental disorders	17 (12.4%)	52 (5.2%)
Attention deficit hyperactivity disorder	26 (19.0%)	117 (11.8%)

Note: Total sum equals more than 100% as it is common to have more than more psychiatric diagnosis per patient. IQR: interquartile range.

^aPatients may have ≥1 recorded diagnosis within the category.

Table 2. Characteristics of recorded episodes in the Danish Poison Information Centre and the Danish National Patient Registry for patients with repeated poisoning behaviour in Denmark from 2013 to 2017.

	Danish Poison Information Centre	Danish National Patient Registry
Episodes, total	1752	19,492
Episodes per patient
Median (IQR)	10 (8–15)	14 (10–22)
Substances per episode
1	1187 (67.8%)	14,849 (76.2%)
2–4	519 (29.6%)	4508 (23.1%)
5–10	46 (2.6%)	135 (0.7%)
Type of ingestion
Medication	1420 (81.1%)	16,351 (83.9%)
Recreational substances	79 (4.5%)	2184 (11.2%)
Alcohol	64 (3.7%)	4381 (22.5%)
Other	290 (16.6%)	1803 (9.2%)
Regulatory status of medications
Over the counter	702
Prescription only	1885
Reason for ingestion
Intentional	1519 (86.7%)
Unintentional	175 (10.0%)
Unclear	58 (3.3%)
Risk assessment
Mild	502 (28.7%)
Severe	1166 (66.6%)
Not registered	84 (4.8%)

Note. IQR: interquartile range.

Table 3. The most commonly ingested medications in patients with repeated poisoning episodes.

Top 20 medications	Drug class	Generic name	Number of episodes	Number of patients	Episodes per patient, mean^a	Total number of poison episodes, mean^a	Prescription only medication/OTC	Hospital admissions	Intensive care unit admissions
1	Antipsychotic	Quetiapine	258	71	3.6	12.7	POM	81%	11.2%
2	Non-opioid oral analgesic	Paracetamol	183	74	2.5	14.2	OTC	74%	1.1%
3	Antihistamine	Cyclizine	177	16	11.1	19.3	OTC	86%	1.1%
4	Anxiolytic	Oxazepam	146	56	2.6	14.3	POM	75%	14.4%
5	Antipsychotic	Olanzapine	129	39	3.3	15.2	POM	82%	12.4%
6	NSAID	Ibuprofen	120	48	2.5	13.3	OTC	63%	2.5%
7	Antipsychotic	Chlorprothixene	101	36	2.8	16.5	POM	84%	7.9%
8	Hypnotic	Zopiclone	72	25	2.9	14.6	POM	92%	6.9%
9	Antihistamine	Promethazine	54	19	2.8	13.8	OTC/POM^b	87%	13.0%
10	Antidepressant	Sertraline	50	24	2.1	13.3	POM	82%	2.0%
11	Antiepileptic	Lamotrigine	47	19	2.5	18.1	POM	66%	4.3%
12	Antiepileptic	Pregabalin	47	10	4.7	12.5	POM	85%	4.3%
13	Opioid oral analgesic	Tramadol	42	19	2.2	14.5	POM	81%	9.5%
14	Antipsychotic	Aripiprazole	40	19	2.1	17.5	POM	83%	15.0%
15	Non-opioid oral analgesic	Acetylsalicylic acid	38	11	3.5	9.0	OTC	87%	10.5%
16	Antiepileptic	Clonazepam	35	12	2.9	13.8	POM	77%	2.9%
17	Antidepressant	Mirtazapine	34	14	2.4	16.9	POM	74%	2.9%
18	ADHD drugs	Methylphenidate	33	13	2.5	11.8	POM	73%	6.1%
19	Antidepressant	Venlafaxine	32	15	2.1	16.7	POM	88%	9.4%
20	Antiepileptic	Valproate	26	12	2.2	12.3	POM	85%	3.8%

Note. The most common ingested medications in patients with repeated poisoning behaviour in Denmark from 2013 to 2017. OTC: over the counter; NSAID: non-steroidal anti-inflammatory drug; POM: prescription only medication; ADHD: attention deficit hyperactive disorder.

^aMean only for patients with at least one poison episode with the specific drug.

^bPromethazine changed status from OTC to POM during the study period (December 2014).

Figure 2. Kaplan–Meier estimates of mortality for subjects with repeated poisoning incidents in the Danish National Patient Registry cohort compared to the Kaplan–Meier estimates of mortality for the background population. CI: Confidence interval.