The purpose of this meta-analysis was to assess the association between Depression and suicidal ideation. We use data from six studies to do a meta-analysis. We applied the random-effects analytic model and calculated a pooled odds ratio. 

The combined effect size showed that odds of suicidal ideation among people with Depression is 4.88 times higher than those peoples without Depression (ORMH 4.88 95%CI 2.04, 11.72) Test for overall effect: Z = 3.55 (P = 0.0004) Heterogeneity: Tau² = 1.11; Chi² = 100.97, df = 5 (P < 0.00001); I² = 95%. The magnitude of suicidal ideation among people with Depression is 46.39% (528) and peoples without Depression is 17.79 % (315) from the total, 39.13 % (1138) is depressed and 60.86% (1779) not depressed. The overall proportion of Suicidal Ideation among the included studies is 28.98 % (843). The total number of study subjects included in our systematic review and meta-analysis is 2908.

The Diagnostic and Statistical Manual of Mental Disorders defines suicidal ideation as a thinking about, making plans for suicide and self-destructive act with a clear expectation of death that is non-fatal [1]. The magnitude of suicide indicates as it is a serious public health problem in the world [2]. It affects more than 50 million people in the world [3]. The worldwide prevalence  of suicide is estimated to raise to 2.4% by 2020 year, and the rate of death due to suicide will be one person every 20 s [4]. It is the second leading cause of death among adolescents and young adults [5-6]. Suicidal acts result from a combination of biological, psychological, sociological, cultural and environmental factors [7].

Depression is the top risk factor and risk factors for suicidal ideation can be divided into 3 categories: psychiatric disorders, life events, and family history [8]. The most frequently reported factors correlated with suicidal behavior are being male, psychological distress [9], depression [10], dissatisfaction with academic performance, feeling neglected by parents [11-12], substance abuse, psychiatric disorders [13], drug use [14], depressive symptoms [15], first year and pre-clinical phase, homesick [16], alteration in thyroid, and prolactin hormone [17].

The loss of loved one by suicide and emotional turmoil related to bereavement also linked with increase in suicidal behavior [18]. There is also a strong positive correlation of suicide in those who are young age, male and a higher level of education [19]. However, there are limited data specifically on the association between Depression and suicide ideation.

Therefore, this study aimed to assess the association between Depression and suicidal ideation. This study would help as an input of information for health providers /psychiatrists on the relationship between depression and suicidal ideation and leads to plan suicide prevention strategies 

Data

Electronic databases were searched .on reference manager software and quality assessments of the included studies were performed by assessing the risk of bias. A meta-analysis was applied to test the association between Depression and suicidal ideation. Words used to search literatures are, 'factors associated with suicidal ideation and suicidal ideation.

Study selection

Figure 1 shows the selection process of the articles searched. The initial search on reference manager software results in 89 and after duplicates removed 47 records remain and 14 studies assess for eligibility and finally 6 studies included in our systematic review and meta-analysis 

Figure 1. Study flow diagram

Measures

Suicidal ideation was the outcome variable depression was the exposure. The two variables measured in deferent way in different studies included in our systematic review and met analysis 

Analysis

By design, this study is secondary data analysis. Using Review Manager Version 5.3 software and Meta Essential software. We determined combined effect size and associated 95% confidence intervals to describe the relationship between Depression and Suicidal ideation. We calculated combined effect size across the studies using the Mantel-Haenszel (MH) statistic (the DerSimonian-Laird method or random effect model). 

We applied the random effects analytic model to account for inter survey variation and to provide a more conservative effect than a fixed model would have provided. The I 2 statistics were used to assess the variability among the included studies and above 50% was considered as significant.

The characteristics of included studies according to sample size. Depression and Suicidal Ideation.

Table 1. Characteristics of the included studies

The magnitude of suicidal ideation among   people with Depression is 46.39% (528) and peoples without Depression is 17.79 %( 315) from the total, 39.13 %( 1138) is depressed and 60.86% (1779)  not depressed. The overall proportion of Suicidal Ideation among the included studies is 28.98 %( 843). The total number of study subjects included in our systematic review and meta-analysis is 2908.

Meta-analysis

Figure 2, Forest plot for the association between Depression and suicidal ideation

The combined effect size showed that odds of suicidal ideation among people with Depression is 4.88 times higher than those peoples without Depression (ORMH 4.88 95%CI 2.04, 11.72)  Test for overall effect: Z = 3.55 (P = 0.0004) Heterogeneity: Tau² = 1.11; Chi² = 100.97, df = 5 (P < 0 xss=removed>

Assessment of publication bias 

Figure 3. Funnel plot for the association between Depression and suicidal ideation

Table 2

As funnel plot showed there is no publication bias Egger Regression p value =- 0.205 Begg & Mazumdar p value = 0.851.

Source of heterogeneity 

Figure 4. Moderator analysis for the association between Depression and suicidal ideation

Table 3

As sample size increase the effect size decrease (B=0.00 p Value =0.004), so the source of heterogeneity is sample size difference of the included studies .

This study is similar with previous studies in USA (20) ,Colombia, (21), Brazil (22), China  (10)  Nepal (11), Washington (23), Canada,(24), Bosnia and Herzegovina (25), Poland (26), Brazil (27), Malaysia (28), South Africa (29), Nigeria(30), Eriteria [8], in India (31), Ethiopia (32-35), Addis Ababa Ethiopia [36]. This may be due to high depressive symptoms that are related to suicidal risk and thoughts. A Depression that affects everyday activities, social interactions, and low self-esteem can cause increased suicidal thoughts. Many of this previous studies explained that the presence of depression is highly associated with suicidal ideation. It also indicated that the decreased level of serotonin neurotransmitter in the brain of a depressed individual was found to be associated with increased suicidal behavior [37].

The possible explanation may also be due to a direct effect of depression which makes individuals to feel hopeless, isolated and worthless [17]. The other possible explanation might be due to high levels of stress associated with adjusting to a new social environment and could be due to the effect of high dose of alcohol consumption [8]. This systematic review and meta-analysis is inconsistence with previous study [38]. The reason for the difference between our findings and this study may be the difference in sample size, study population and study participants characteristic. This study indicated that depressed persons have higher risk of suicidal ideation than no depressed persons and health provider should give focus or priority to identify depressed people as well as to assess risk of suicide in depressed people.

This study showed that peoples with Depression are more likely to have suicidal ideation than people without Depression.

All data are included in the paper.

The authors declare that they have no conflicts of interest.

• Kaleab Tesfaye Tegegne, Eleni Tesfaye Tegegne and Mekibib Kassa Tessema were responsible for conceptualization, project administration, software, supervision, and development of the original drafting of the manuscript. 
• Kaleab Tesfaye Tegegne, Eleni Tesfaye Tegegne , Wosenyeleh Semeon Bagajjo, and Mekibib Kassa Tessema , Muse Rike   , Alelign Tadele Abebe , Berhanu Bifato 1were participated in quality assessment of articles, methodology, validation, and screening of research papers
• All authors contributed with data analysis, critically revised the paper, and agreed to be accountable for their contribution.

We would like to thank all the primary authors of the included articles.

Ethics approval and consent to participate

Not applicable.

Competing of interest 

The authors have declared that there is no competing interest.

Consent for publication 

Not applicable.

Funding 

Not any funding received for this work.