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Background: Tumor necrosis factor-alpha (TNF-α) is a potent immune-inflammatory mediator involved in the regulation of bone resorption. The single nucleotide polymorphism G-308A in the TNF-α gene increases the level of this cytokine. This phenomenon is also related to several diseases. Although the association between TNF-α (G-308A) polymorphism and dental peri-implant disease has been investigated, results have remained controversial. Hence, we performed this meta-analysis to provide a comprehensive and systematic conclusion on this topic. Methods: We performed a systematic literature search in PubMed, Embase, ISI Web of Science, Cochrane Library, and Chinese National Knowledge Infrastructure until July 2015. A fixed-effect model was established to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs). The calculated values were then used to assess the strength of the association between the TNF-α (G-308A) polymorphism and the dental peri-implant disease risk. The heterogeneity between included studies was evaluated with Cochran Q and I2 statistics. Interstudy publication bias was investigated with a funnel plot. Results: Six eligible studies were included in this meta-analysis. The pooled ORs did not reveal a significant relationship between the TNF-α (G-308A) polymorphism and the disease susceptibility. Subgroup analyses in terms of ethnicity and disease type yielded similar results. Conclusion: Our meta-analysis revealed that TNF-α (G-308A) polymorphism was not significantly associated with the risk of dental peri-implant disease. However, further studies with large sample sizes should be performed to verify these results.

Supplemental Digital Content is available in the text, The laparoscopic cholecystectomy (LC) is an important approach of treating acute cholecystitis and the timing of performing this given treatment is associated with clinical outcomes. Although several meta-analyses have been done to investigate the optimal timing of implementing this treatment, the conflicting findings from these meta-analyses still confuse decision-making. And thus, we performed this systematic review to assess discordant meta-analyses and generate conclusive findings to facilitate informed decision-making in clinical context eventually. We electronically searched the PubMed, Cochrane Library, and EMBASE to include meta-analysis comparing early (within 7 days of the onset of symptoms) with delayed LC (at least 1 week after initial conservative treatment) for acute cholecystitis through August 2015. Two independent investigators completed all tasks including scanning and appraising eligibility, abstracting essential information using prespecified extraction form, assessing methodological quality using Oxford Levels of Evidence and Assessment of Multiple Systematic Reviews (AMSTAR) tool, and assessing the reporting quality using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), as well as implementing Jadad algorithm in each step for the whole process. A heterogeneity degree of ≤50% is accepted. Seven eligible meta-analyses were included eventually. Only one was Level I of evidence and remaining studies were Level II of evidence. The AMSTAR scores varied from 8 to 11 with a median of 9. The PRISMA scores varied from 19 to 26. The most heterogeneity level fell into the desired criteria. After implementing Jadad algorithm, 2 meta-analyses with more eligible RCTs were selected based on search strategies and implication of selection. The best available evidence indicated a nonsignificant difference in mortality, bile duct injury, bile leakage, overall complications, and conversion to open surgery, but a significant reduction in wound infection, hospitalization, and operation duration and improvement of the quality of life when compared early LC with delayed LC. However, number of work days lost, hospital costs, and patient satisfaction are warranted to be assessed further. With the best available evidence, we recommend early LC to be as the standard treatment option in treating acute cholecystitis.

Supplemental Digital Content is available in the text, Some epidemiological studies have investigated the relationship between genetic polymorphisms of DRD2, COMT, DBH, and MAO-A and migraine susceptibility, but the results are still inconsistent. Thus, our aim was to further assess the association through a meta-analysis. We examined 5 single nucleotide polymorphisms (SNPs) in 4 genes, including DRD2 rs1799732 and rs6275, DBH rs7239728, MAI-A-VNTR, and COMT rs4680, and performed a meta-analysis of 11 published case–control studies including 3138 cases and 4126 controls. Odd ratios (ORs) with 95% confidence intervals (95% CIs) were used to evaluate the association between the 5 genetic polymorphisms and migraine susceptibility. There was no significant relationship between migraine susceptibility and 4 genetic polymorphisms of DRD2 rs1799732 and rs6275, DBH rs7239728, and MAO-A-VNTR. Nevertheless, decreased risk of migraine was observed to be in association with COMT rs4680 polymorphism in overall analysis (AA vs. GG + GA: OR = 0.76, 95% CI = 0.60–0.97, PHet > 0.642, I2 = 0), and in Caucasian group after subgroup analysis (AA vs. GG + GA: OR = 0.75, 95% CI = 0.58–0.96, PHet > 0.433, I2 = 0). Studied polymorphisms of DRD2, DBH, and MAO-A genes may not be associated with migraine susceptibility. However, COMT rs4680 polymorphism may decrease the risk of migraine, especially in Caucasians. The failure to evaluate environmental influence and provide adjusted effect size estimates highlights the need for additional studies in a large number to take these factors into consideration, thus better elucidating the role of the genes tested in migraine.

Multiple studies had focused on the association between interleukin-1 (IL-1) rs1143634 polymorphism and aggressive periodontitis (AgP) susceptibility, but the results remained inconclusive. Therefore, this meta-analysis was conducted to explore its role in the development of AgP. PubMed and Embase databases were searched up to April 15, 2014. After study selection and data extraction form eligible studies, meta-analysis was performed. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the association. All the analysis was performed using Comprehensive Meta-Analysis software. Finally a total of 25 case-control studies were included. The pooled results showed non-association between AgP susceptibility and IL-1 rs1143634 polymorphism [for T vs. C: OR = 0.99, 95% CI = 0.79-1.23; for TT vs. CC: OR = 1.14, 95% CI = 0.78-1.66; for CT vs. CC: OR = 0.97, 95% CI = 0.70-1.36; for (CT + TT) vs. CC: OR = 1.02, 95% CI = 0.76-1.37; for TT vs. (CT + CC): OR = 1.22, 95% CI = 0.85-1.75]. Subgroup analyses remain did not find any association. No publication bias was detected. Hence, our meta-analysis showed that IL-1β rs1143634 polymorphism is not linked to AgP susceptibility, regardless of ethnicity.

MOOSE checklist in current meta-analysis. (DOC 73 kb)

Objective. Conflicting results on the association between MTHFR polymorphism and head and neck cancer (HNC) risk were reported. We therefore performed a meta-analysis to derive a more precise relationship between MTHFR C677T polymorphism and HNC risk. Methods. Three online databases of PubMed, Embase, and CNKI were researched on the associations between MTHFR C677T polymorphism and HNC risk. Twenty-three published case-control studies involving 4,955 cases and 8,805 controls were collected. Odds ratios (ORs) with 95% confidence interval (CI) were used to evaluate the relationship between MTHFR C677T polymorphism and HNC risk. Sensitivity analysis, cumulative analyses, and publication bias were conducted to validate the strength of the results. Results. Overall, no significant association between MTHFR C677T polymorphism and HNC risk was found in this meta-analysis (T versus C: OR = 1.04, 95% CI = 0.92–1.18; TT versus CC: OR = 1.15, 95% CI = 0.90–1.46; CT versus CC: OR = 1.00, 95% CI = 0.85–1.17; CT + TT versus CC: OR = 1.01, 95% CI = 0.87–1.18; TT versus CC + CT: OR = 1.11, 95% CI = 0.98–1.26). In the subgroup analysis by HWE, ethnicity, study design, cancer location, and negative significant associations were detected in almost all genetic models, except for few significant risks that were found in thyroid cancer. Conclusion. This meta-analysis demonstrates that MTHFR C677T polymorphism may not be a risk factor for the developing of HNC.