Most published meta-regression analyses based on aggregate data suffer from methodological pitfalls: a meta-epidemiological study.

BACKGROUND: Due to clinical and methodological diversity, clinical studies included in meta-analyses often differ in ways that lead to differences in treatment effects across studies. Meta-regression analysis is generally recommended to explore associations between study-level characteristics and treatment effect, however, three key pitfalls of meta-regression may lead to invalid conclusions. Our aims were to determine the frequency of these three pitfalls of meta-regression analyses, examine characteristics associated with the occurrence of these pitfalls, and explore changes between 2002 and 2012. METHODS: A meta-epidemiological study of studies including aggregate data meta-regression analysis in the years 2002 and 2012. We assessed the prevalence of meta-regression analyses with at least 1 of 3 pitfalls: ecological fallacy, overfitting, and inappropriate methods to regress treatment effects against the risk of the analysed outcome. We used logistic regression to investigate study characteristics associated with pitfalls and examined differences between 2002 and 2012. RESULTS: Our search yielded 580 studies with meta-analyses, of which 81 included meta-regression analyses with aggregated data. 57 meta-regression analyses were found to contain at least one pitfall (70%): 53 were susceptible to ecological fallacy (65%), 14 had a risk of overfitting (17%), and 5 inappropriately regressed treatment effects against the risk of the analysed outcome (6%). We found no difference in the prevalence of meta-regression analyses with methodological pitfalls between 2002 and 2012, nor any study-level characteristic that was clearly associated with the occurrence of any of the pitfalls. CONCLUSION: The majority of meta-regression analyses based on aggregate data contain methodological pitfalls that may result in misleading findings.

Homicide-suicides compared to homicides and suicides: systematic review and meta-analysis.

Homicide-suicides, the murder of one or several individuals followed by the suicide of the perpetrator, are rare but have devastating effects on families and communities. We did a systematic review and meta-analysis of studies comparing perpetrators of homicide-suicides with perpetrators of simple homicides and suicides and examined the proportion of firearm use and its correlation with firearm availability. We searched Medline and Embase from inception to July 2012 and identified 27 eligible studies. Perpetrators of homicide-suicides were older and more likely to be male and married to or separated from their victims than perpetrator of simple homicides or suicides. Influence of alcohol and a history of domestic violence or unemployment were less prevalent in homicide-suicides than in homicides. The proportion of firearm use in homicide-suicides varied across countries and was highest in the USA, Switzerland and South Africa, followed by Australia, Canada, The Netherlands and England and Wales, with a strong correlation between the use of firearms and the level of civilian gun ownership in the country. Our results indicate that homicide-suicides represent a distinct entity, with characteristics distinguishing them both from homicides and suicides.