In Japan, a dramatic jump in the year-over-year number of suicides occurred in 1998 (32,863 victims compared to 1997 (24,391)); suicide rates have been 25.2–27.0 (per 100,000; from 1998 to 2006) since 1998, whereas, previously, they had remained between 17.0 to 21.0 for over 20 years (from 1978 to 1997). This recent increase has been primarily due to a rise in the number of suicides in middle-aged men, with men in their 50s representing the sharpest peak [1, 2]. However, psychiatric and psychosocial aspects of the current trend in suicide increases are not well understood because only one psychological autopsy study was reported before such an increase in Japan [3]. Instead, better insight into individuals' measures against suicide, who unsuccessfully attempted suicide, should improve our understanding, because an unsuccessful attempt is a high-risk factor for subsequent suicide [4–6]; 44% of suicides have a history of unsuccessful attempts [7]. Previous studies indicated that medically serious suicide attempters and suicide victim are two overlapping populations, and share common characteristics [8–10]. Continual care for those that have attempted suicide has the potential for suicide prevention, and the World Health Organization proposed an intervention study of medically treated suicide attempters [11].

This report presents demographic and psychiatric data of patients who suffered serious medical injury as a result of a suicide attempt. It is the first detailed and comprehensive study since the rapid increase in the suicide rate in Japan in 1998. Such data are expected to be crucial if we are to develop effective strategies for high-risk groups regarding suicide.

The present study was performed at the Critical Care and Emergency Center, Yokohama City University Medical Center, from April 1, 2003 to September 30, 2005. There are four emergency medical centers in Yokohama, Japan, with a population of 3.5 million people. Our center receives all patients who require critical care from the southern catchment area of the city. During the study period, 2967 patients entered the center, and cases of both suicide attempters and completers numbered 544 (18%). Among these, 320 attempters (126 men and 194 women) who were admitted underwent psychiatric evaluation. The remaining 224 patients did not undergo psychiatric interview because of death on arrival, early death, transfer to another unit with prolonged consciousness disturbances, or an extremely short hospital stay.

The 320 patients were interviewed by at least two trained psychiatrists. Their intent to die was confirmed. Sociodemographics, the method of attempted suicide, current psychiatric treatment, previous suicide attempt/deliberate self-harm, and any family history of suicide were extracted from the interview. Deliberate self-harm was defined as self-destructive behavior without obvious suicidal ideations. Psychiatric diagnosis was made according to the DSM-IV criteria[12] by agreement among more than two psychiatrists (the authors).

Subjects were divided into two groups based on the lethality of the attempt according to the operational criteria of Beautrais [8], and subsequently analyzed. The high-lethality group was defined using the following criteria: 1) mechanical ventilation was required for life support; 2) surgery was performed under general anesthesia; 3) the method of attempted suicide carried a high risk of death, specifically, hanging, gunshot, jumping from a high place, inhalation of gas, solvents, or other agricultural chemicals, thermal injury, or drowning. Data were also stratified according to age. Special attention was given to the high-risk group, males in their 40s and 50s, defined as "middle-age men".

Data are presented as the mean ± SD. Statistical analyses were conducted using SPSS for Windows Version 11.5 (SPSS, Chicago, IL, USA). The chi-square test, Fisher's exact test, and the Mann-Whitney rank sum test were used in comparisons as indicated. A probability level of P < 0.05 was considered significant.

This study was approved by the ethical committee of Yokohama City University School of Medicine.

Suicide attempt is a known potent risk factor. About 0.5% to 2% of individuals complete suicide, and 5% commit suicide within 9 years. [5] Previous studies have found that victims of both successful and failed suicide attempts who suffer medically serious complications share some common characteristics [8–10]. Consequently, evaluation of those attempting suicide can offer: 1. insight into the pathology of successful suicide by providing psychological data, 2. biological studies can be performed, and 3. through prospective studies, the efficacy of interventions can be assessed [13]. In Japan, psychological autopsy studies are not generally accepted. Surveys of failed suicide attempts and interventions for those attempting suicide have been more highly regarded to date.

Few reports have examined psychiatric diagnoses in cases of suicide attempts following the recent rise in the suicide rate in Japan [14–16]. Murase, et al. (2003) studied 100 attempted suicide cases, attempters and found that depressive disorders were the most frequent pathology. Ichimura, et al. (2005) investigated changes in the prevalence of psychiatric diagnoses (ICD-10 classification) between 1992–1993 and 2000 in over 200 attempted suicide cases, and discovered that F20–29 diagnoses had decreased and disorders other than F30–39, F40–48, and F60–69 had also decreased. The present study is the first large-scale study involving a comprehensive evaluation of attempted suicide cases in Japan since the dramatic increase in the suicide rate began.

The most common method of attempted suicide in our subjects was self-poisoning, and the majority of patients who overdosed used psychotropic drugs that had been prescribed. It is known that methods vary between countries and regions. Jumping from a high place seemed more common in our subjects than in previous studies [17–19]. Our center is located in an urban area containing many high-rise office buildings. Therefore, it is possible that there was a selection bias. Conversely, ingestion of pesticides or agricultural chemicals was very rare in our urban population. Attempts using firearms were also rare. Possession of firearms is strictly controlled in Japan, whereas firearm use is the most common method of suicide/attempted suicide in the United States [20].

The overall female/male ratio of cases of attempted suicide was 1.58. This ratio was higher in the low- (2.17) than the high-lethality group (1.34). This is consistent with other reports that women are more likely to attempt suicide than men, but men are more likely to succeed [21, 22]. Thus, it seems that patients in the high-lethality group resembled suicide victims, at least from the viewpoint of gender.

Our study was consistent with other reports noting a high prevalence of patients who met the DSM-IV criteria for a psychiatric diagnosis, especially axis I. It has been well established that the vast majority of suicide victims exhibit psychiatric morbidity [23–32]. Bertolote, et al. (2004) compiled psychological autopsy studies, and found that 98% of suicide victims had a diagnosis of at least one mental disorder, with mood disorders accounting for 30.2%, followed by substance -abuse related disorders, and schizophrenia. In our study, 81% of attempted suicide cases had an axis I diagnosis. Mood disorders were the most common, as reported in previous studies which targeted those attempting suicide [33, 34]. Thirty-seven percent of all subjects had an axis II diagnosis, and 28% of patients who met the criteria for an axis I diagnosis had concomitant personality disorders. The frequency of personality disorder has been reported to be higher in parasuicide than suicide [35–37]. Engström, et al. (1997) [38] reported that 63% of those attempting suicide met the DSM-III-R criteria for personality disorder. Their subjects were all hospitalized, but whether they suffered from medically serious conditions is unknown.

Middle-aged men are an important subgroup. This population is less likely to have a history of self-harm, but is more likely to use lethal means such as laceration. They are more likely to be depressed, but the prevalence of mood disorders is more common, while they are less likely to seek medical attention, even though the Japanese medical system provides prompt, direct access to a psychiatrist.

This study is the first comprehensive evaluation of consecutive patients admitted to hospitals because of serious medical injury sustained due to a suicide attempt. Our result provides data that can be used to develop and refine strategies for preventing suicide. The present study suggested that introduction and continuation of psychiatric treatment is important for those who had not been treated. Accessibility and availability of psychiatric treatment is a key especially for men. On the other hand, optimal psychiatric treatment should be taken into consideration for those who attempted suicide during outpatient clinic treatment.