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Objective: Well-conducted meta-analyses (MAs) are considered as one of the best sources of clinical evidence for treatment decision. MA with methodological flaws may introduce bias and mislead evidence users. The aim of this study is to investigate the characteristics and methodological quality of MAs on diabetes mellitus (DM) treatments., Design: Systematic review., Methods: Cochrane Database of Systematic Review and Database of Abstract of Reviews of Effects were searched for relevant MAs. Assessing methodological quality of systematic reviews (AMSTAR) tool was used to evaluate the methodological quality of included MAs. Logistic regression analysis was used to identify association between characteristics of MA and AMSTAR results., Results: A total of 252 MAs including 4999 primary studies and 13,577,025 patients were included. Over half of the MAs (65.1%) only included type 2 DM patients and 160 MAs (63.5%) focused on pharmacological treatments. About 89.7% MAs performed comprehensive literature search and 89.3% provided characteristics of included studies. Included MAs generally had poor performance on the remaining AMSTAR items, especially in assessing publication bias (39.3%), providing lists of studies (19.0%) and declaring source of support comprehensively (7.5%). Only 62.7% MAs mentioned about harm of interventions. MAs with corresponding author from Asia performed less well in providing MA protocol than those from Europe., Conclusions: Methodological quality of MA on DM treatments was unsatisfactory. There is considerable room for improvement, especially in assessing publication bias, providing lists of studies and declaring source of support comprehensively. Also, there is an urgent need for MA authors to report treatment harm comprehensively., (© 2016 European Society of Endocrinology.)

Ethnopharmacological Relevance: Meta-analysis (MA) on Chinese herbal medicine (CHM) trials is increasingly published and indexed in major international databases but their trustworthiness and clinical applicability is uncertain. We aimed to assess the characteristics and methodological quality of MA on CHM., Materials and Methods: Cross-sectional study. MA published during 1993-2013 was sampled from MEDLINE, EMBASE, Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effect. Bibliographical characteristics were abstracted and methodological quality was assessed using the validated AMSTAR tool by two independent reviewers., Results: Total of 201 MA were included and half were published in or after 2009. Only 7.5% being updates of previous reviews. Majority are published in journals with low or no impact factor, with a median of 1.5. These MA demonstrated methodological strengths in ensuring comprehensive literature search, providing characteristics of the included studies, assessing the scientific quality of included studies and appropriately using the scientific quality of included studies in formulating conclusions. Nevertheless, weaknesses in protocol provision, listing of included and excluded studies, inclusion of grey literature, use of appropriate meta-analytic technique as well as reporting of funding sources were prevalent. CHM and control interventions pooled in majority of MA are found to have substantial clinical heterogeneity in terms of composition, dosage form and route of administration., Conclusions: There are rooms for improvement in methodological rigor, and in choosing clinically homogenous interventions and control for statistical pooling. These shortcomings limit the trustworthiness and clinical applicability of existing MA on CHM trials. To overcome the limitations of pair-wise meta-analysis in synthesizing trials comparing different CHM and control interventions, the potential of network meta-analysis should be explored., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Meta-analysis (MA) of randomised trials is considered to be one of the best approaches for summarising high-quality evidence on the efficacy and safety of treatments. However, methodological flaws in MAs can reduce the validity of conclusions, subsequently impairing the quality of decision making., Aims: To assess the methodological quality of MAs on COPD treatments., Methods: A cross-sectional study on MAs of COPD trials. MAs published during 2000-2013 were sampled from the Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effect. Methodological quality was assessed using the validated AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool., Results: Seventy-nine MAs were sampled. Only 18% considered the scientific quality of primary studies when formulating conclusions and 49% used appropriate meta-analytic methods to combine findings. The problems were particularly acute among MAs on pharmacological treatments. In 48% of MAs the authors did not report conflict of interest. Fifty-eight percent reported harmful effects of treatment. Publication bias was not assessed in 65% of MAs, and only 10% had searched non-English databases., Conclusions: The methodological quality of the included MAs was disappointing. Consideration of scientific quality when formulating conclusions should be made explicit. Future MAs should improve on reporting conflict of interest and harm, assessment of publication bias, prevention of language bias and use of appropriate meta-analytic methods.