Systematic Reviews
Copyright ©The Author(s) 2015.
World J Psychiatr. Jun 22, 2015; 5(2): 243-254
Published online Jun 22, 2015. doi: 10.5498/wjp.v5.i2.243
Table 3 Critique of Positive Association Studies
Yang[45]This study uses aggregated population data and only investigates contemporaneous and very short term lagged effects of economic variables on suicide rates. This study supports the evidence of other studies based in the United States that economic recession can exert a short term impact on suicide rates; although the utility of this study in identifying causal associations is questionable
Lester et al[47]No individual level evidence included in this study. Suicide rates by age category were not computed
Gavrilova[16]Mortality data quality is questionable as is cause of death coding. Suicide data could have been inaccurately coded leading to underestimates of suicide mortality. No individual level evidence was included and only descriptive statistical analysis was performed
Ruhm[19]No individual level data was included in the study. No information on suicide rates by gender was provided. The inclusion of 4 yr lags for unemployment lags, whilst an improvement on similar published studies only provides a short term insight into the interaction between fluctuations in unemployment and suicide rates
Brainerd[21]Gross national product per capita and employment rates used in the study are likely to be underestimates. This means that regression estimates are more likely to identity regressors as not exerting an effect on suicide rates. The panel used in this study is biased by missing or incomplete data for a number of included countries. No individual-level data was included in the study
Lester[42]Spatial analyses of suicide rates within states were not performed, thus providing no insight into any clustering of suicide mortality within states. Age specific suicide rates were not included although a breakdown of suicide mortality by ethnicity was. No individual level data was included in the study
Kim et al[28]Mortality data was derived from death certificates which may not be fully accurate. The use of aggregated population data limits the ability to make causal inferences about the interaction between economic recession and suicide. An age breakdown of suicide rates was not provided
Gerdtham[12]Unlike most other included studies, a large individual level dataset was collected using a prospective cohort study design. Numerous sensitivity analyses were performed to address potential flaws with the initial study design. However, the decrease in the male mortality rates is concentrated in the first few years of the study period meaning there may be an variable that has not been accounted for in the study that is causing this effect
Khang et al[15]Concerns have been raised by this study about the quality of cause of death coding in South Korea which may have affected the accuracy of data in this study. Total suicides may have been underreported due to a miscoding of such deaths as being unintentional - as a result of stigma. Only descriptive analyses of suicide data were performed, meaning any omitted variable bias has not been corrected for
Tapia Granados[44]This study benefits from analysing the impact of a number of economic cycles on suicide mortality over a long period of time. Data on suicide mortality and economic indicators were taken from a range of official statistical sources, to provide data for the century studied in the study. This study does not explore the effect of mediating factors which relate economic recession to suicide. By studying aggregated population data rather than individual level data, this study only provides evidence for an association between recession and suicide
Granados[20]The study design used is very similar to the design used in Ruhm (2000)[19] and the finding that suicide rates increase during recessions is consistent with Ruhm’s study. This study also expands on Ruhm’s work by providing sex specific mortality rates. However like Ruhm’s study, only short term effects of recession on suicide rates are explored; and the use of panel data can exacerbate attenuation bias resulting from underestimates of suicide mortality in official data. As with all ecological studies, the ability to make causal inferences between recession and suicide is impaired by a lack of individual level data
Berk et al[50]Seasonality in suicide rates was not adjusted for in this study. No individual level data was included in this study either. Lagged effects of changes in included economic indicator were not computed
Granados[29]Correlation and regression analyses were both performed in this study to elucidate the relationship between recession and suicide. The time series data in this study has also been detrended to make it more suitable for regression analysis. As the author suggests, the study would have been strengthened if a panel study design had been used as the association between economic recession and suicide could be tested across many sub-regions in Japan
Altinanahtar et al[49]This study is notable for using auto regressive distributed lags which allow for the exploration of long run relationships between variables. This study’s focus on Turkey is also notable as it is a middle income rather than a high income country and high income countries form the majority of countries studied by the literature. This study however does not study suicides according to age and gender and no individual level data has been included
Chang et al[14]This study provides one of the first analyses of the effects of the 1998 Asian financial crisis on the main countries in the region who were affected. Of concern is the potential difference in the accuracy of suicide coding practices across studied countries as well as the completeness of suicide data. State specific effects such as political unrest (e.g., in Hong Kong) were not fully controlled for in this study
Tapia Granados et al[18]Regression analyses of the interaction between the depression and overall mortality were performed but not for suicide rates specifically. Only descriptive statistics were used to describe the interaction between suicide rates and the depression. A breakdown of suicide rates by age or gender was not provided
Stuckler et al[22]Of note in this study is the analysis of the effect of social protection spending on the interaction between unemployment and suicide that this study performed. Using unemployment as a proxy for economic conditions, the effects of both smaller and larger increases in unemployment on suicide rates was tested as well. Other included studies tended to not perform the aforementioned analyses. This study only analysed the short term effects of recession and as with many of the included studies, this study was analysing the impact of recession on populations rather than individuals
Wu et al[46]The authors of this study opted to detrend time series data in order to make it more suitable for regression analysis. The risk of omitted variable bias was well mitigated with the inclusion a range of potential confounders. The authors state that the results should be approached with caution due to data limitations, but these limitations were not specified
Ceccherini-Nelli et al[48]Variations in suicide documentation across the four countries studied may vary which complicates comparisons made between these countries. The co-integration analyses performed in this study allow for the analysis of the long term interactions between economic variables proxying economic conditions and suicide rates; which is a major strength of this study. These analyses however only test for associations rather than causality
Luo et al[43]The nonparametric analyses used in these studies did not allow for the analysis of the effect of recession severity or length on suicide rates, as all recessions were presumed to be of the same length and severity. Multiple regression analysis was not performed thus increasing the likelihood that omitted variables have biased the results
Stuckler et al[17]This study represents a very preliminary analysis of suicide data from 2009. This means that any effects of the 2008 recession would not have arisen fully and any conclusions made based on data analysis may be premature
Barr et al[23]The unemployment rate in this study is based upon the number of claimants of unemployment benefits which may underestimate the true unemployment rate. At the national level, the level of fiscal consolidation within England, does not seem to have been estimated or controlled. This is significant as this variable could influence both the unemployment and suicide rates, thus acting as a confounder. The sub-regions of England investigated in this study have different levels of deprivation and the unemployment rate may have differing impacts on the suicide rate in these regions, which are not expressed in the study itself. Only the immediate effects of economic recession have been investigated as the lagged effects have not been calculated
Reeves et al[24]United States suicide data may underestimate the true suicide rate. The excess mortality estimates rely on short term extrapolations of pre-recession suicide trends
Lopez Bernal et al[31]The use of interrupted time series analysis allowed for the controlling of seasonality in time series data. Unlike many other included studies, the extent of residual autocorrelation in the time series data was estimated and a control analysis was conducted; using mortality from accidental falls as an outcome measure rather than suicide mortality. Because of the low number of monthly suicide rates in some regions of Spain, regions within the country had to be combined in order to increase statistical power. This means there were less units of observation for the interaction between economic recession and suicide
Chang et al[27]Differences in coding and classification of suicide may lead to an introduction of bias between countries, which may be exacerbated by the large number of countries studied (54 countries in this study). The sample of studied countries is also skewed by the presence of a large number of high income countries and an underrepresentation of low income countries; particularly from Sub-Saharan Africa. This means that overall excess mortality estimates may be more of a representation of the relationship between economic recession and suicide in high income countries than in low income countries
Garcy et al[13]As in [12], this study analyses individual level evidence and the results seem to suggest a causal association. The great strength of this study is its very large sample size of individuals (more than 3 million) and the inclusion of a range of socioeconomic variables within the cox regression analyses that were conducted. As this study provided further analyses where individuals who had previously attempted suicide or had a previous mental health diagnosis were excluded, the relationship between unemployment and suicide in this study is less likely to be spurious; especially considering the fact that this study has been conducted at the individual level. However this study could not test whether mental health deteriorated as a result of unemployment meaning the behaviour of an important mediating factor has not been elucidated in this study
Chan et al[30]Suicide data derived from death certificates may be more vulnerable to misreporting bias. This study attempts to focus the study of the South Korean population by stratifying by occupational status as well as gender; although the flaws associated with using aggregated population data remain. The inclusion of students and housewives in the “unemployed” label used by the S. Korean national statistical office, may distort the relationship between economic recession and suicide rates as these groups may respond to the onset of recession quite differently compared to those who lost their jobs as a result of recession
Madianos et al[32]The study only explores the short term effects of economic recession on suicide rates. Monthly and regional suicide rates which may have provided a greater insight into the timing and spatial distribution of suicides were not included
Phillips et al[25]This study performed age and sex stratified analyses of the association of between included economic variables and suicide rates. The authors acknowledge the potential impact of omitted variables such as gun ownership which were not included in analyses because of a lack of comprehensive data
Phillips et al[25]This study only provides evidence of changes in suicide mortality during an economic recession. Data is provided up until 2010 but negative GDP growth only stopped in 2013 with a return to recession in 2014. Therefore this study does not capture the full extent of the suicide mortality response to recession conditions
Reeves et al[26]The confidence intervals for the estimated excess European suicide mortality attributable to the recession are quite wide. The unadjusted difference between baseline suicide rates and recession suicide rates are compared to estimate suicide rates; meaning that the impact of confounders has not been adjusted for, nor has any seasonality in the time series data been controlled