Clinical characteristics and outcomes of patients with mental illnesses who attempted suicide by drug overdose: A retrospective analysis of 109 cases

Abstract Objective Individuals with mental illnesses are exposed to an increased risk of suicide. In this study, we aimed to investigate the clinical characteristics and outcome of psychiatric patients who attempted suicide by drug overdose and required emergency care. Methods A retrospective study was carried out in the Department of Emergency, the First Affiliated Hospital, Zhejiang University School of Medicine. Electronic medical records of psychiatric patients who were hospitalized due to suicide attempts from March 2019 to February 2022, with a discharge diagnosis of drug overdose were reviewed. Suicide‐related data of patients were collected, including suicide month, time from suicide to admission, type of drugs, the number of tablets taken, as well as demographic and clinical profiles (e.g., gender, age, marital status, profession, physical comorbidities, and diagnosis of mental illness). Results In the results, half of the patients were young people, female patients accounted for a higher proportion (72.5%), and the incidence of suicide was higher in winter than other seasons. Among the 109 psychiatric patients, 60 patients (55.0%) had a history of major depressive disorder, and 86 patients (78.9%) committed suicide with various psychotropic drugs, among which anxiolytics were the most commonly used drugs. Thirty‐seven patients (33.9%) experienced severe physical complications caused by drug overdose, with lung infections being the most common. The clinical outcome of most patients was favorable following emergent treatment, while 2 patients (1.8%) older than 80 failed to survive. Conclusion A better understanding of psychiatric patients referred to emergency care due to suicide by drug overdose helps to improve the clinical management and prognosis of patients.


INTRODUCTION
Suicide is a major public health issue worldwide. According to data released by World Health Organization (WHO), about 800,000 to 1 million deaths per year are due to suicide, and it was noted as the second leading cause of death in the young age group (15∼29 years old) globally (WHO Mental Health). Notably, mental illnesses are important risk factors for suicidal behavior (Dahale et al., 2017;Qin, 2011), and a wide range of mental illnesses increase the risk of experiencing suicide ideation (Callanan & Davis, 2012). A recent systematic review and meta-analysis suggested that individuals with mental illness had a nearly eight-fold increased risk of suicide compared with those without mental illness (Too et al., 2019). More precisely, patients with major depressive disorder, bipolar disorder, or schizophrenia, respectively, had an estimated 20-fold, 17-fold, or 13-fold greater risk of suicide compared with that of the general population (Chesney et al., 2014).
There are several researches studying the characteristics of suicide in patients with different mental illnesses (Lang et al., 2016;Qin, 2011;Zeppegno et al., 2015). Miller et al. found that the suicide rate of patients with bipolar disorder may be related to various factors, such as gender, age, disease severity, and disease subtype (Miller & Black, 2020). By investigating the characteristics of individuals who had attempted suicide by drug overdose, with special attention on the amount of drugs taken, Manabu et al. showed that the psychiatric outpatient history seemed not to be a risk factor for suicide attempts by ingesting higher doses of drugs (Yasuda & Kobayashi, 2019).
Suicide attempt refers to a nonfatal, self-directed, potentially injurious behavior with any intent to die (O'Connor et al., 2013). Patients with mental illnesses are more accessible to psychotropic drugs, which may be overdosed as the culprit for suicide. At present, there is no study that specifically characterizes the clinical profiles of patients with mental illnesses who attempt suicide by drug overdose. Herein, we hypothesized that patients with mood disorders were at a greater risk of suicide by overdosing psychotropic drugs. In the current study, we thus aimed to address the clinical characteristics and outcome of this population, and proposed a diagnosis and treatment framework for clinical management.

Study subjects
With the assistance of the Electronic Case Record System, patients with a discharge diagnosis of drug overdose were screened. Subjects met the following criteria were included (1) suicide attempt by drug overdose with their own medications and (2) a preexisting diagnosis of any mental illness before suicide attempt.

Data collection
For patients enrolled, clinical profiles such as the suicide month, time from suicide to admission, types of drugs (psychotropic drugs, e.g., antidepressants, anxiolytics, antipsychotics, anticonvulsants, mood stabilizers, and nonpsychotropics drugs) and the number of tablets taken were collected. We also recorded the demographic and other data, including gender, age, marital status, profession, physical comorbidities, and diagnosis of mental illnesses.

Statistical analyses
The statistical analysis was performed with SPSS 25.0 for Windows (SPSS, Inc., Chicago, IL). The categorical variables were presented as numbers (frequency). The continuous variables were presented as mean ± standard deviation (SD) or Min-Max values.

Demographic and clinical characteristics
In total, 109 cases meeting the inclusion criteria were included in the final analysis. Of these patients, 79 (72.5%) were women, 30 (27.5%) were men, and the male to female ratio was 1:2.63. The age of all patients ranged between 12 and 87 years old, with an average age had comorbid hypertension, with a mean age of 63.3 ± 5.2 years old.

3.3.2
Drugs used for suicide

DISCUSSION
In this study, we presented the demographic and clinical characteristics of patients with preexisting mental illnesses who attempted suicide by drug overdose. Although the clinical outcomes of most patients were favorable following emergency care, early prevention and effective management of drug overdose is still challenging in this population, especially in young females with major depressive disorder and bipolar disorder.
Our research showed that females accounted for a significant higher proportion than males among all included patients. We also found that the majority of suicide attempts by drug overdose were young people (18-43 years old), which was consistent with previous studies (Yasuda & Kobayashi, 2019). A previous scoping review found that over-thecounter analgesics and hypnotics were frequently used by the females, the young, and people with mental disorders for self-harm and suicidal behaviors (Shoib et al., 2022). A possible explanation is that young patients are more likely to suffer from depressive episodes and need to cope with higher life stress. In our samples, the incidence of suicide by drug overdose in winter was higher than other seasons. This was not consistent with previous researches showing that spring and summer were the peak seasons of suicide (Galvão et al., 2018;Yang et al., 2019). Zeppegno and colleagues also found a greater risk of suicide during the warmer months of the year (from April to September) (Zeppegno et al., 2015 ). The divergence of these findings may be attributed to the climate and cultural differences in different countries. Among the 109 patients, more than half of these patients had a preexisting diagnosis with major depressive disorder, and 14.7% with bipolar disorder. Therefore, our data suggests that young and female patients with a preexisting mood disorder are possibly at a higher risk of attempting suicide by drug overdose, which warrants more attention and supervision from healthcare providers and caregivers. When the patient is still in the acute phase of depressive episodes, a comprehensive and dynamic assessment of suicidal risk is necessary. In our study, nearly 80% patients did suicide by psychotropic drugs. Of special note, compared to the general population, patients with mental illnesses are more accessible to psychotropic drugs, which would be used as the culprit for drug overdose. We recommend that only a limited number of drugs would be prescribed when the mental status of the patient is still unstable. In view of early prevention, therefore, guardians or other caregivers of patients with mental illnesses are responsible to supervise the drugs. Complications occurred in about one-third of patients, mainly involving the lung, kidney, and liver, suggesting that the adverse effects of drug overdose on these organs need full evaluation. were not enrolled for comparison. In addition, our sample is small, and further researches with larger samples and better designs are needed to verify our findings and explore more detailed information on suicide behaviors among psychiatric patients with drug overdose.
In conclusion, we comprehensively depicted the demographic and clinical profiling of suicide by drug overdose among psychiatric patients and proposed a clinically useful flowchart for dealing with such conditions. Given the high risk of suicide in patients with mental illnesses, preventive interventions and early warning systems need to be constructed.

AUTHOR CONTRIBUTIONS
DL and JBL conceived and designed the study. NYC and SLL conducted the literature search and wrote the first draft of the manuscript. HS conducted the data extraction. Statistical analyses were conducted by SLL under the supervision of JBL and DL. All authors contributed to and have approved the final manuscript.

CONFLICT OF INTEREST STATEMENT
All authors claimed that there was no conflict of interest.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.