Based on the demographic data, most of the patients in this study were single, female, in early adulthood, educated, Buddhist, and unemployed. With regard to the clinical characteristics, most of the patients were diagnosed as having first episode MDD with severe depression, had a median treatment duration of 8 weeks, and received a number of medications.
A total of 76.4% of the participants in this study were shown to present suicidality, which is higher than past reports in Thailand and other countries. One study found a 62.3% rate of suicidality [13], whereas another one found only 32.1% of suicidality [11] in Thai MDD patients. A study in Europe [12] found only 46.67% of suicidality in MDD patients. Prevalence of suicidal ideation (62.4%) and suicide attempt within a month (35.4%) that were found were higher than past studies in Asia. Rates of suicidal ideation reported in China [25, 26] and Singapore [27] ranged from 49–55% among MDD patients and a recent meta-analysis showed a 24% 1-month prevalence of Chinese MDD patients having suicide attempts [28]. The variation of the prevalence may be influenced by the different tools using to evaluate suicidality. The variety of inclusion criteria is another important factor. Most earlier studies recruited patients in various phases of illness including active, remission and recovery leading to less severe symptoms of depression, which was probably the reason for having lower rates of suicidality. This study included patients who were treated within the 6-month period of being diagnosed or of a recurrent episode, which was considered as an active episode of depression [14–16]. For this reason, patients were currently suffering from an active illness, which may have led to a higher severity of depression and resulted in the higher suicidality rate.
Another interesting issue is the lower mean age of the sample in this study compared with those of other studies, which may affect the level of suicidal behavior, and the results of this study also show that an age of 20 years or lower is associated with a higher level of suicide risk. Nowadays, depressive disorders can be found in the younger age groups, which is often associated with genetic factors and a family history of depression [29], can cause more severe symptoms [30], and may lead to higher rates of suicidality. A previous study found that pre-adult onset MDD patients (age lower than 18 years) were associated with a history of suicide attempts and current suicidal thoughts [31]. A consistent result was found in the recurrent MDD patients, in which the pre-adult onset group was associated with suicidality [32]. The results indicating a higher suicidality rate in the current study may be explained by the younger median age level of the sample population and the earlier age of the onset of depressive disorder.
To explain the persistence of depressive symptoms and suicidality despite being treated, first, one-third to half of patients were reported as ‘treatment-resistant’ in past studies [33, 34] and only two-third of patients recovered from depression within 6 months [16]. It was speculated that those non-responsive patients had a chronicity of symptoms that lead to suicidality, as shown in a study conducted in Korea [35] that found that 63% of patients presented persistent suicidality after a 12-week period of treatment. Second, the mechanisms of antidepressant treatment leading to suicide were proposed [36], for example, side effects from antidepressants and treatment inefficacy. Lastly, many psychosocial stressors were presented among suicidal groups, of which moderate-to-severe psychological distress was found to be associated with completed suicide [37]. All of these reasons may explain why individuals currently treated within a 6-month period in this study were still suicidal.
The demographic, clinical and social factors associated with moderate-to-high suicide risk that were consistently found in this current and many previous studies include being non-religious, being unemployed, having a history of substance use [3, 38–40], having a higher severity of depression [12, 38–40], being an in-patient [41], shorter duration of treatment [42], low social support, and high severity of health stress events [4, 39].
The interesting finding in terms of the associated clinical characteristics was that of benzodiazepines use. Benzodiazepines are anxiolytics that are used for relief of several symptoms, including insomnia. Recent studies reported that somatic symptoms such as insomnia are associated with suicide [43, 44]. In addition, receiving benzodiazepines may be associated with increased aggression [45] and may result in disinhibition [46], which may be the factors that contribute to suicidal behavior.
Regarding the remarkable social factors, poor family relationships and functioning were highly associated with suicide risk. This shows that family issues are the social problems that need to be focused on. In a previous study, poor family communication was associated with a history of suicide attempts in depressive disorder patients [5]. Consistent data was found in research on adolescents, in which perceptions of family functioning were associated with suicidal ideation and suicide attempts [47]. Moreover, interpersonal role disputes and interpersonal deficits, which had been previously proved to be associated with depression [48], were found to be the important issues for the suicidal group in this study. According to Erikson’s concept of development across the lifespan [49], a person in early adulthood (21–40 years of age) needs to achieve intimacy and closeness within a partnership. Most of the patients in the study were in this stage of development; therefore, the problems of interpersonal relationships are important to them, for example, an argument with their close friends, family members, colleagues or partners.
According to the results of the present study, suicidality is common among depressive disorder patients, especially in the initial 6-month period of treatment. Depressive severity and various factors including family and interpersonal problems should be assessed, particularly in early adulthood patients, when these issues are crucial. Adequate treatment of depression should be prompt, and early intervention in family and interpersonal problems may be helpful in reducing the risk of suicide.
There were several limitations in this study. First, due to the descriptive design, the associations identified did not indicate a causal relationship. Second, the samples were collected from only one hospital in Thailand, which may result in the findings not being representative of all depressive disorder patients. The influence of different sociocultural characteristics should also be considered. Lastly, other factors that may affect suicidality, such as psychiatric comorbidity and personality disorders, were not evaluated. Further investigation should be conducted in order to determine when the suicidality may decrease during the course of treatment and what types of interventions that will help to reduce the suicidality can be applied.