Systematic reviews and meta-analyses on treatment of asthma: critical evaluation

Jadad, Alejandro R.; Moher, M; Browman, George P.; Booker, Lynda; Sigouin, Christopher; Fuentes, M. De; Stevens, Robert S.

doi:10.1136/bmj.320.7234.537

Cited by 215 publications

(135 citation statements)

References 20 publications

(18 reference statements)

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“…95 A Cochrane review by Haynes and colleagues 88,89 examined a diverse range of interventions designed to promote adherence with prescribed medications across a number of medical and psychiatric conditions. Five relevant interventions in asthma were included amongst the total of 33 studies reviewed, two of which showed clear effects on adherence and treatment outcomes in favour of the intervention.…”

Section: Psycho-educational Interventions In Mixed Diseasesmentioning

confidence: 99%

A systematic review to examine the impact of psycho-educational interventions on health outcomes and costs in adults and children with difficult asthma

Smith

Mugford

Holland

et al. 2005

Health Technol Assess

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Section: Psycho-educational Interventions In Mixed Diseasesmentioning

confidence: 99%

A systematic review to examine the impact of psycho-educational interventions on health outcomes and costs in adults and children with difficult asthma

Smith

Mugford

Holland

et al. 2005

Health Technol Assess

View full text Add to dashboard Cite

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“…Previous studies attempted to review systematic reviews and meta-analyses in the fields of asthma (Jadad et al, 2000), back and neck pain (Assendelft et al, 1995;Furlan et al, 2001;Hoving et al, 2001), analgesia and anaesthesia (Jadad and McQuay, 1996;Choi et al, 2001), emergency medicine (Kelly et al, 2001) and surgery (Dixon et al, 2005). With no exception, those studies discussed the (predominantly low) quality of systematic reviews.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, systematic reviews are considered a scientific exercise in itself. However, still a considerable amount of so-called systematic reviews, especially those sponsored by the industry or non-Cochrane reviews, appear to have methodological flaws (Jadad et al, 2000). Moreover, studies on the same topic that were found to be of good quality may produce contradictory evidence (Jadad and McQuay, 1996;Furlan et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Limited evidence for effects of diet for type 2 diabetes from systematic reviews

2007

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Objective: Systematic reviews are an appraised method to summarize research in a concise and transparent way, and may enable to draw conclusions beyond the sum of results of individual studies. We assessed the results, quality and external validity of systematic reviews on diet in patients with type 2 diabetes. Design, setting, subjects: We systematically searched for systematic reviews on nutritional interventions in patients with type 2 diabetes that used a reproducible search strategy in at least one major database that applied some form of quality assessment. We assessed quality and the external validity of the retrieved systematic reviews. Outcomes were defined as statistical metaanalyses or narrative results using a predefined and reproducible method. Results: Six systematic reviews met the inclusion criteria, investigating dietary interventions in general (n ¼ 3), chromium supplementation (n ¼ 1), fish-oil (n ¼ 1) or herbs and nutrition supplements (n ¼ 1). Quality assessment showed minimal/minor flaws in four cases and major/extensive flaws in two cases. All reviews had insufficient data needed to judge external validity. In reviews with minimal/minor flaws, we found beneficial effects of very-low-calorie diets and fish-oil supplements. However, the external validity of these results could not be assessed sufficiently. Conclusions: Systematic reviews largely failed to produce knowledge beyond the sum of the original studies. Furthermore, judgment of external validity was hampered in most cases owing to missing data. To improve the quality and usefulness of systematic reviews of dietary interventions, we recommend the application of more focused research questions, but with broader inclusion criteria, for example, the use of observational studies.

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“…For example, Jadad and colleagues (Jadad, Moher, Browman, Booker, Sigouin, Fuentes, et al, 2000) analyzed 50 systematic reviews and meta-analyses of asthma treatment and found that most reviews published in peer-reviewed journals had serious methodological flaws that limited their usefulness; Cochrane reviews were more rigorous and better reported than those published in peer-reviewed journals. All industry-funded reviews were judged to have serious flaws.…”

Section: Current Practicementioning

confidence: 99%

Evidence-based or biased? The quality of published reviews of evidence-based practices

Littell

2008

Children and Youth Services Review

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Objective: To assess methods used to identify, analyze, and synthesize results of empirical research on intervention effects, and determine whether published reviews are vulnerable to various sources and types of bias.Methods: Study 1 examined the methods, sources, and conclusions of 37 published reviews of research on effects of a model program. Study 2 compared findings of one published trial with summaries of results of that trial that appeared in published reviews.Results: Study 1: Published reviews varied in terms of the transparency of inclusion criteria, strategies for locating relevant published and unpublished data, standards used to evaluate evidence, and methods used to synthesize results across studies. Most reviews relied solely on narrative analysis of a convenience sample of published studies. None of the reviews used systematic methods to identify, analyze, and synthesize results. Study 2: When results of a single study were traced from the original report to summaries in published reviews, three patterns emerged: a complex set of results was simplified, non-significant results were ignored, and positive results were over-emphasized. Most reviews used a single positive statement to characterize results of a study that were decidedly mixed. This suggests that reviews were influenced by confirmation bias, the tendency to emphasize evidence that supports a hypothesis and ignore evidence to the contrary.Conclusions: Published reviews may be vulnerable to biases that scientific methods of research synthesis were designed to address. This raises important questions about the validity of traditional sources of knowledge about "what works," and suggests need for a renewed commitment to using scientific methods to produce valid evidence for practice. Reviews of evidence-based practices 2The emphasis on evidence-based practice appears to have renewed interest in "what works" and "what works best for whom" in response to specific conditions, disorders, and psychosocial problems. Policy makers, practitioners, and consumers want to know about the likely benefits, potential harmful effects, and evidentiary status of various interventions (Davies, 2004;Gibbs, 2003). To address these issues, many reviewers have synthesized results of research on the impacts of psychosocial interventions. These reviews appear in numerous books and scholarly journals; concise summaries and lists of "what works" can be found on many government and professional organizations' websites.In the last decade there were rapid developments in the science of research synthesis, following publication of a seminal handbook on this topic (Cooper & Hedges, 1994). Yet, the practice of research synthesis (as represented by the proliferation of published reviews and lists of evidence-based practices) and the science of research synthesis have not been well-connected (Littell, 2005).In this article, I trace the development and dissemination of information about the efficacy and effectiveness of one of the most prominent evidence-based pract...

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Systematic reviews and meta-analyses on treatment of asthma: critical evaluation

Cited by 215 publications

References 20 publications

A systematic review to examine the impact of psycho-educational interventions on health outcomes and costs in adults and children with difficult asthma

A systematic review to examine the impact of psycho-educational interventions on health outcomes and costs in adults and children with difficult asthma

Limited evidence for effects of diet for type 2 diabetes from systematic reviews

Evidence-based or biased? The quality of published reviews of evidence-based practices

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