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 4 Critique of Negative Association and Inconclusive Studies
Hintikka et al[37]Potential confounding variables such as state health expenditure were not included. Finnish suicide data seems to be highly reliable so incomplete data is less likely to be a major source of bias. The finding that rapid increases in unemployment were not associated with increases in suicide rates is interesting, but the lack of individual level evidence means that underlying explanations for this association cannot be arrived at from this study alone
Rancans et al[35]Only a descriptive analysis of economic and suicide data was performed here meaning the effect of any confounding variables was not controlled for. This study only demonstrates a simple temporal association (or strict lack of it) between unemployment rates, gross domestic product, and suicide rates
Neumayer[40]The panel study design used here is very similar to Ruhm, 2000[19]. Interestingly on sensitivity analysis using gross domestic product as the main proxy for economic fluctuations, variations in suicide mortality no longer behave pro-cyclically. As with the other included panel studies, attenuation bias may be a problem if suicide statistics underestimate suicide mortality
Gonzalez et al[36]Age breakdowns for suicide mortality were not provided. No individual level analyses were performed in this study. This study takes great care in ensuring the quality of its mortality data; going as far as to test whether quality of death classification varies with the economic cycle
Mackenbach et al[39]Differences in the accuracy and quality of cause of death coding and classification between countries and within countries over time may have biased the results of this study. The investigation into the relationship between income and mortality in this study implies a causal relationship between the two, although this is contentious
Saurina et al[41]Using a different regression model to Barr et al, this study contradicts the findings of Barr et al despite the fact that the study location (England) and the study period are very similar. The authors of this paper argue that Barr et al’s methodology is incomplete and has probably produced a spurious relationship between recession and suicide due to not controlling for confounding variables; particularly those with a regional dimension. Despite claiming to improve upon Barr et al’s methodology, this study is still probably biased by the change in classification from ICD-9 to ICD-10 (although Barr et al’s study would be similarly affected). Furthermore the location of suicide (e.g., rural or urban) may have a confounding effect; and this kind of spatial confounding may not have been adequately controlled for in this study
Laanani et al[38]This study provides an interesting insight into the question of a causal link between recession and suicide. By performing a sensitivity analysis to check for confounding by a “crisis effect”, this study found that such an effect varied between countries and the association between unemployment and suicide in studied countries was statistically significant, but fairly weak and variable. This however may be a reflection of the quality of unemployment as a proxy for economic conditions in studies that investigate multiple countries at once. This study also emphasises the inherent problem in trying to investigate causal associations between economic recession and suicide using ecological study designs