Self-poisoning with medications in adolescents: a national register study of hospital admissions and readmissions

Abstract

Objective

To examine characteristics of hospital admissions and risk factors associated with rehospitalization for self-poisoning with medications in adolescents aged 10–19 years.

Method

This study used data from the Norwegian Patient Register from 2008 to 2011. The main outcome was hospital readmission within the observation period. A complementary log–log regression model was used to assess the effect of characteristics at index hospital admission on readmission.

Results

Of 1497 patients, 76.4% were females and 89.8% were aged 15–19 years. At their first hospital admission, about one third received a secondary psychiatric diagnosis. Females (47.5%) were registered with an E-code for intentional self-harm more often than males (33.7%), and females were more often than males discharged to further treatment (27.8% vs. 21.5%). As many as 18.4% were rehospitalized for self-poisoning by medications. Significant predictors for hospital readmission were female sex [hazard ratio (HR)=2.4, 95% confidence interval (CI) 1.7–3.6], discharge to further treatment (HR=2.3, 95% CI 1.8–2.9) and psychiatric secondary diagnoses (HR=1.5, 95% CI 1.2–1.9).

Conclusion

This national study demonstrated significant sex differences in adolescents treated in hospital for self-poisoning with medications. Psychiatric secondary diagnoses had a strong predictive effect on readmission, which indicates the importance of psychiatric/psychosocial assessment of adolescents who are admitted to hospital for self-poisoning with medications.

Introduction

Adolescents who ingested a harmful dose of medications are frequently seen in acute hospital settings in Western countries [1], [2]. Most of these young patients are females in their late adolescence [1], [3], [4]. Nonopioid analgesics, such as paracetamol, are the most common substances ingested, but benzodiazepines, antidepressants and antipsychotics are also used [3], [5], [6]. Significant sex differences have been found regarding suicidal intent [1], psychiatric disorders and place of discharge [7].

Usually, hospital-treated cases of adolescent self-poisoning represent either overdoses with recreational drugs or intentional self-harm [4] where the individual purposely ingests a substance in excess of the prescribed or generally recognized therapeutic dosage [8]. Both types are associated with current psychiatric problems [6], [9] and increased risk of developing psychiatric disorders [10], premature death and suicide [4], [11]. The risk of a fatal outcome, from poisoning or other causes, is further enhanced among those who repeat their self-poisoning behavior [12], [13]. Furthermore, repeated self-poisonings represent severe psychological distress for the adolescents and their families as well as use of substantial amounts of health care resources [14]. Previous studies found that about one-third of the adolescents who were admitted to hospital for self-poisoning had a history of previous self-poisoning(s) [15] and 15%–20% were readmitted within 6–12 months for subsequent self-poisoning(s) [15], [16]. However, these studies included only cases defined as intentional self-harm and cannot be generalized to the total population of adolescents who visit hospital for self-poisoning. Other studies found that 6%–7% were rehospitalized within one year, but these studies were completed two decades ago and limited to hospital activity data from only one city-region [11], [17]. There is a lack of studies examining risk factors for hospital readmission for self-poisoning in adolescents in a national population-wide context. Targeted treatment and prevention strategies depend on updated and representative data of what characterizes those adolescents who self-poison with medications. In particular, those adolescents who repeatedly self-poison form a high-risk population yet are little studied; thus, more knowledge is needed to inform clinicians about factors associated with rehospitalization.

The current study extended the research on adolescent self-poisoning with medications by using national data from the Norwegian Patient Register (NPR) of hospital admissions from 2008 to 2011. We identified all adolescents aged 10–19 years who were admitted to hospital for acute self-poisoning with medications irrespective of the apparent purpose of their act [18]. Side effects or unanticipated reactions from medications taken correctly were not included, nor were poisonings with substances predominantly used for nonmedical reasons (such as pesticides or rodenticides) or intoxications due to addiction [19].

The aims of the study were (a) to examine the characteristics (sex, age, E-code for intentional self-harm, psychiatric disorders) and management (lengths of hospital stay and place of discharge) of hospital admissions for self-poisoning in those aged 10–19 years and (b) to examine whether or not these factors were associated with hospital readmission for self-poisoning.