Most of these studies were underpowered, however, and meta-analyses intended to overcome the effects of inadequate sample sizes in individual RCTs failed to uncover any robust trend toward improved overall survival using prone positioning. Despite significant and sustained increase of oxygenation, prone positioning had no impact on mortality. The use of prone positioning during acute respiratory distress syndrome (ARDS) ventilation has a robust scientific ground and was evaluated in numerous randomised controlled trials (RCTs). Long duration of ventilation in prone position significantly reduces ICU mortality when only ARDS patients are considered. Prone positioning was not associated with a statistical increase in major airway complications. Meta-regression on all studies disclosed only a trend to explain effect variation by prone duration ( P = 0.06). Overall, prone ventilation did not reduce ICU mortality (odds ratio = 0.91, 95% confidence interval = 0.75 to 1.2 P = 0.39), but it significantly reduced the ICU mortality in the four recent studies that enrolled only patients with ARDS (odds ratio = 0.71 95% confidence interval = 0.5 to 0.99 P = 0.048 number needed to treat = 11). The effects of prone positioning differed according to the type of study. The four most recent trials included only ARDS patients, and also applied the longest proning durations and used lung-protective ventilation. Seven RCTs (including 1,675 adult patients, of whom 862 were ventilated in the prone position) were included. We also computed the effects of prone positioning on major adverse airway complications. A relationship between studies' effect size and daily prone duration was sought with meta-regression. The effect size on intensive care unit (ICU) mortality was computed in the overall included studies and in two subgroups of studies: those that included all ALI or hypoxemic patients, and those that restricted inclusion to only ARDS patients. Analysis was made by a random-effects model. RCTs that compared ventilation of adult patients with ALI/ARDS in prone versus supine position were included in this study-level meta-analysis. We updated a meta-analysis on this topic. Current evidence suggests that TNF-α G-308A polymorphism may be associated with increased risk for acute MI.In patients with acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS), recent randomised controlled trials (RCTs) showed a consistent trend of mortality reduction with prone ventilation. Other subgroup analyses revealed no significant associations. However, when subgroup analysis was performed according to the stages of MI, results indicated that there was a significant association between TNF-α G-308A polymorphism and the risk of acute MI. The overall results showed that there was no significant association between TNF-α G-308A polymorphism and MI risk. In total, 12 publications with 13 case-control studies consisting of 6037 cases and 7262 controls were included in our meta-analysis. The odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the association between the selected variables using the Comprehensive Meta-Analysis v2.2 software. Study selection and data extraction were carried out independently by two authors. Reported studies published before Mawere included and analyzed from the PubMed and Embase databases. Hence, we performed a meta-analysis to evaluate the association between TNF-α G-308A polymorphism and MI. However, differing results from various studies have led to controversial conclusions. The tumor necrosis factor-alpha (TNF-α) G-308A polymorphism has been suggested to be a susceptibility factor for myocardial infarction (MI).