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PubMed1999

Rational decision-making in mental health: the role of systematic reviews.

BACKGROUND: "Systematic reviews" have come to be recognized as the most rigorous method of summarizing confusing and often contradictory primary research in a transparent and reproducible manner. Their greatest impact has been in the summarization of epidemiological literature - particularly that relating to clinical effectiveness. Systematic reviews also have a potential to inform rational decision-making in healthcare policy and to form a component of economic evaluation. AIMS OF THE STUDY: This article aims to introduce the rationale behind systematic reviews and, using examples from mental health, to introduce the strengths and limitations of systematic reviews, particularly in informing mental health policy and economic evaluation. METHODS: Examples are selected from recent controversies surrounding the introduction of new psychiatric drugs (anti-depressants and anti-schizophrenia drugs) and methods of delivering psychiatric care in the community (case management and assertive community treatment). The potential for systematic reviews to (i) produce best estimates of clinical efficacy and effectiveness, (ii) aid economic evaluation and policy decision-making and (iii) highlight gaps in the primary research knowledge base are discussed. Lastly examples are selected from outside mental health to show how systematic reviews have a potential to be explicitly used in economic and health policy evaluation. RESULTS: Systematic reviews produce the best estimates of clinical efficacy, which can form an important component of economic evaluation. Importantly, serious methodological flaws and areas of uncertainty in the primary research literature are identified within an explicit framework. Summary indices of clinical effectiveness can be produced, but it is difficult to produce such summary indices of cost effectiveness by pooling economic data from primary studies. Modelling is commonly used in economic and policy evaluation. Here, systematic reviews can provide the best estimates of effectiveness and, importantly, highlight areas of uncertainty that can be used in "sensitivity analysis". DISCUSSION: Systematic reviews are an important recent methodological advance, the potential for which has only begun to be realized in mental health. This use of systematic reviews is probably most advanced in producing critical summaries of clinical effectiveness data. Systematic reviews cannot produce valid and believable conclusions when the primary research literature is of poor quality. An important function of systematic reviews will be in highlighting this poor quality research which is of little use in mental health decision making. IMPLICATIONS FOR HEALTH PROVISION: Health care provision should be both clinically and cost effective. Systematic reviews are a key component in ensuring that this goal is achieved. IMPLICATIONS FOR HEALTH POLICIES: Systematic reviews have potential to inform health policy. Examples presented show that health policy is often made without due consideration of the research evidence. Systematic reviews can provide robust and believable answers, which can help inform rational decision-making. Importantly, systematic reviews can highlight the need for important primary research and can inform the design of this research such that it provides answers that will help in forming healthcare policy. IMPLICATIONS FOR FURTHER RESEARCH: Systematic reviews should precede costly (and often unnecessary) primary research. Many areas of health policy and practice have yet to be evaluated using systematic review methodology. Methods for the summarization of economic data are methodologically complex and deserve further research

Journal Article↗
PubMed2003

The inclusion of reports of randomised trials published in languages other than English in systematic reviews.

OBJECTIVE: To assemble a large dataset of language restricted and language inclusive systematic reviews, including both conventional medicinal (CM) and complementary and alternative medicine (CAM) interventions. To then assess the quality of these reports by considering and comparing different types of systematic reviews and their associated RCTs; CM and CAM interventions; the effect of language restrictions compared with language inclusions, and whether these results are influenced by other issues, including statistical heterogeneity and publication bias, in the systematic review process. DATA SOURCES: MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews and the Centralised Information Service for Complementary Medicine. REVIEW METHODS: Three types of systematic reviews were included: language restricted; language inclusive/English language (EL) reviews that searched RCTs in languages other than English (LOE) but did not find any and, hence, could not include any, in the quantitative data synthesis; and systematic reviews that searched for RCTs in LOE and included them in the quantitative data synthesis. Fisher's exact test was applied to compare the three different types of systematic reviews with respect to their reporting characteristics and the systematic review quality assessment tool. The odds ratio of LOE trials versus EL trials was computed for each review and this information was pooled across the reviews to examine the influence that language of publication and type of intervention (CM, CAM) have on the estimates of intervention effect. Several sensitivity analyses were performed. RESULTS: The LOE RCTs were predominantly in French and German. Language inclusive/LOE systematic reviews were of the highest quality compared with the other types of reviews. The CAM reviews were of higher quality compared with the CM reviews. There were only minor differences in the quality of reports of EL RCTs compared with the eight other languages considered. However, there are inconsistent differences in the quality of LOE reports depending on the intervention type. The results, and those reported previously, suggest that excluding reports of RCTs in LOE from the analytical part of a systematic review is reasonable. Because the present research and previous efforts have not included every type of CM RCT and the resulting possibility of the uncertainty as to when bias will be present by excluding LOE, it is always prudent to perform a comprehensive search for all evidence. This result only applies to reviews investigating the benefits of CM interventions. This does not imply that systematic reviewers should neglect reports in LOE. We recommend that systematic reviewers search for reports regardless of the language. There may be merit in including them in some aspects of the review process although this decision is likely to depend on several factors, including fiscal and other resources being available. Language restrictions significantly shift the estimates of an intervention's effectiveness when the intervention is CAM. Here, excluding trials reported in LOE, compared with their inclusion, resulted in a reduced intervention effect. The present results do not appear to be influenced by statistical heterogeneity and publication bias. CONCLUSIONS: With the exception of CAM systematic reviews, the quality of recently published systematic reviews is less than optimal. Language inclusive/LOE systematic reviews appear to be a marker for a better quality systematic review. Language restrictions do not appear to bias the estimates of a conventional intervention's effectiveness. However, there is substantial bias in the results of a CAM systematic review if LOE reports are excluded from it.

Complementary Therapies↗
PubMed2001

Evidence-based practice: extending the search to find material for the systematic review.

BACKGROUND: Cochrane-style systematic reviews increasingly require the participation of librarians. Guidelines on the appropriate search strategy to use for systematic reviews have been proposed. However, research evidence supporting these recommendations is limited. OBJECTIVE: This study investigates the effectiveness of various systematic search methods used to uncover randomized controlled trials (RCTs) for systematic reviews. Effectiveness is defined as the proportion of relevant material uncovered for the systematic review using extended systematic review search methods. The following extended systematic search methods are evaluated: searching subject-specific or specialized databases (including trial registries), hand searching, scanning reference lists, and communicating personally. METHODS: Two systematic review projects were prospectively monitored regarding the method used to identify items as well as the type of items retrieved. The proportion of RCTs identified by each systematic search method was calculated. RESULTS: The extended systematic search methods uncovered 29.2% of all items retrieved for the systematic reviews. The search of specialized databases was the most effective method, followed by scanning of reference lists, communicating personally, and hand searching. Although the number of items identified through hand searching was small, these unique items would otherwise have been missed. CONCLUSIONS: Extended systematic search methods are effective tools for uncovering material for the systematic review. The quality of the items uncovered has yet to be assessed and will be key in evaluating the value of the systematic search methods.

Humans↗
PubMed2004

Systematic reviews in laboratory medicine: principles, processes and practical considerations.

BACKGROUND: Systematic reviews and meta-analyses are generally accepted to represent the highest level of evidence, and are a cornerstone in practising evidence-based medicine. So far, these efforts have been largely confined to the evaluation of the efficacy and effectiveness of therapeutic and preventive interventions. Systematic reviews in laboratory medicine are scarce and many of them do not meet essential quality criteria [Clin. Chem. Lab. Med. 38 (2000) 577]. Most of these problems are related to the poor design and heterogeneity of primary research, and that there are no agreed methods or quality standards for making systematic reviews in laboratory medicine. AIMS AND OBJECTIVES: For better evidence in laboratory medicine, not only higher quality primary studies but also standardized methodologies for designing, conducting and reporting systematic reviews in diagnostics are needed. The aim of this review is to present the general principles and provide a step-by-step process of systematic reviewing in laboratory medicine. METHODS: This narrative review is based on the overview of the medical literature on the methodology of systematic reviewing and that of the "state of the art" of evidence-based diagnosis. RESULTS: Systematic reviews of diagnostic interventions differ from that of therapeutic interventions in the methods of question formulation, the choice of study design, the assessment of study quality and the statistical methods used to combine results. Therefore, the general principles of systematic reviewing are adapted to the specialist field of laboratory medicine. The process of systematic reviewing consists of six key steps: (1) preparation for the review, (2) systematic search of the primary literature, (3) selection of papers for review, (4) critical appraisal of the selected literature, (5) analysis and synthesis of data, and (6) interpretation of data. The most important technical and methodological aspects of each step and the essential elements of a good systematic review in laboratory medicine are presented. CONCLUSIONS: Systematic reviews of diagnostic interventions support clinical and policy decisions, the development of practice guidelines, clinical audit, technology assessment, economic evaluations, education and training, and identify gaps in our knowledge for future research. Systematic reviewing of laboratory data is expected to result in better, bigger and more reliable primary studies, which hopefully will support the diffusion of new diagnostic technologies with scientifically proven efficacy and effectiveness in the future.

Clinical Laboratory Techniques↗
PubMed2005

Falsifications and corroborations: Karl Popper's influence on systematics.

Over the last three decades, the philosophy of Karl Raimund Popper has had a strong influence on the field of systematic biology. Unequivocally, no other philosopher's work has had such an influence during this formative period in systematics. Much, but not all, of the early discourse on Popper and systematics dealt with the philosophical basis of systematics as a science. More recently Popper's work has been discussed in the systematics literature in relation to specific methodologies such as parsimony and maximum likelihood. In this paper, we provide the reader with a concise summary of Popper's ideas relevant to systematics, review the systematic literature invoking or declining Popper's importance to the field, and make a recommendation for the future course of philosophical thinking in systematics. We try to make clear various authors' interpretations of Popper's work and how those interpretations have impacted systematic thought. Although the reader may come away from this review with a clearer idea of Popper's relevance or lack thereof, our primary hope is that the reader will be compelled to question him- or herself about the philosophical basis of the systematic work that he or she does, and to delve into the literature herein cited. We begin by presenting a synopsis of Popper's philosophical views to allow those views to be placed in the context of systematics.

Likelihood Functions↗
PubMed2003

Considering resistance in systematic reviews of antibiotic treatment.

CONTEXT: Microorganisms resistant to antibiotic drugs are a threat to the health and chances of survival of patients. Systematic reviews on antibiotic drugs that ignore the topic of resistance present readers with a skewed view, emphasizing short-term efficacy or effectiveness while ignoring long-term consequences. OBJECTIVES: To examine whether systematic reviews of antibiotic treatment consider resistance; if not, to find out whether data on resistance were reported in the original trials; and based on that, to offer a framework for taking resistance into account in systematic reviews. DATA SOURCES: The Cochrane Database of Systematic Reviews (the Cochrane Library, 2001, issue 2); and MEDLINE, 1996-2000. STUDY SELECTION: (i) Systematic reviews or meta-analyses of antimicrobial therapy, published during 1996-2000. (ii) Randomized, controlled trials abstracted in systematic reviews that addressed a topic highly relevant to antibiotic resistance. DATA EXTRACTION: We examined each systematic review, and each article, to see whether the implications of resistance were discussed; and whether data on resistance were collected. RESULTS: Out of 111 systematic reviews, only 44 (40%) discussed resistance. Ten reviews (9%) planned or performed collection of data on the response of patients with susceptible or resistant isolates. In 22 systematic reviews (20%), collection of data on induction of resistance was planned or performed. The topic of 41 reviews was judged highly relevant to resistance, and these reviews extracted data from 337 articles, out of which we retrieved 279 articles (83%). In 201 (72%) articles, resistance was discussed or data pertaining to it were collected. Ninety-seven articles (35%) gave actual data on resistance of pathogens to the study drugs, 71 articles (25%) data on efficacy of antibiotic drugs in patients with susceptible and resistant pathogens, and 55 articles (20%) provided data on infection or colonization with resistant strains during treatment. CONCLUSIONS: Most systematic reviews on antibiotic treatment ignored the issue of resistance, although many of the original articles referred to it and some reported relevant data. Reviewers should collect data on resistance and discuss the implications in their discussion and sections concerned with policy implications.

Anti-Bacterial Agents↗
PubMed2006

Comparison of reports of randomized controlled trials and systematic reviews in surgical journals: literature review.

OBJECTIVES: Randomized controlled trials and systematic reviews of such trials are the gold standard for assessing the effectiveness of interventions. There have been concerns about the anecdotal evidence underpinning many of the interventions used and introduced into surgical care. The American College of Surgeons has prioritized the need for more trials and systematic reviews of trials. To investigate the assertion that the methodological quality of studies conducted in surgery is in general poor and to assess the possible impact of new policy developments in the US, we sought to compare the number and proportion of published randomized controlled trials and systematic reviews in the leading two US and UK general surgical journals. Two reviewers systematically and independently hand searched all issues of these journals over a 12-month period to identify randomised controlled trials and systematic reviews. DESIGN: Systematic searching and independent abstraction of data from all volumes of the top two general surgical journals published in the USA and the UK in 2004. SETTING: 519 original reports in UK journals and 616 original reports in USA journals. MAIN OUTCOME MEASURES: Number and proportion of randomized controlled trials and systematic reviews. RESULTS: Overall, the proportion of randomized controlled trials in all four journals was 5.6% (95% confidence interval [CI] 4.4-7.0) and 5.2% (95% CI 4.1-6.7) for systematic reviews. For journals published in the UK 29/519 (5.6%) of the publications were reports of randomized controlled trials, and for the USA journals this figure was 34/616 (5.5%); odds ratio [OR]=0.99, 95%CI 0.6-1.6; P=0.96. Systematic reviews were significantly more commonly reported in the UK journals: UK 37/519 (7.1%) versus USA 22/616 (3.6%); OR=0.48, 95%CI 0.3-0.8; P<0.01. CONCLUSIONS: The concerns expressed almost a decade ago remain valid: there are still very few reports of randomized controlled trials and systematic reviews published in leading USA and UK surgical journals, with relatively little difference between these countries in the proportion of reported studies employing these designs. The American College of Surgeons initiative has yet to make an impact.

Biomedical Research↗
PubMed2001

The required number of treatment imaging days for an effective off-line correction of systematic errors in conformal radiotherapy of prostate cancer--a radiobiological analysis.

BACKGROUND AND PURPOSE: To use radiobiological modelling to estimate the number of initial days of treatment imaging required to gain most of the benefit from off-line correction of systematic errors in the conformal radiation therapy of prostate cancer. MATERIALS AND METHODS: Treatment plans based on the anatomical information of a representative patient were generated assuming that the patient is treated with a multi leaf collimator (MLC) four-field technique and a total isocentre dose of 72 Gy delivered in 36 daily fractions. Target position variations between fractions were simulated from standard deviations of measured data found in the literature. Off-line correction of systematic errors was assumed to be performed only once based on the measured errors during the initial days of treatment. The tumour control probability (TCP) was calculated using the Webb and Nahum model. RESULTS: Simulation of daily variations in the target position predicted a marked reduction in TCP if the planning target volume (PTV) margin was smaller than 4 mm (TCP decreased by 3.4% for 2 mm margin). The systematic components of target position variations had greater effect on the TCP than the random components. Off-line correction of estimated systematic errors reduced the decrease in TCP due to target daily displacements, nevertheless, the resulting TCP levels for small margins were still less than the TCP level obtained with the use of an adequate PTV margin of approximately 10 mm. The magnitude of gain in TCP expected from the correction depended on the number of treatment imaging days used for the correction and the PTV margin applied. Gains of 2.5% in TCP were estimated from correction of systematic errors performed after 6 initial days of treatment imaging for a 2 mm PTV margin. The effect of various possible magnitudes of systematic and random components on the gain in TCP expected from correction and on the number of imaging days required was also investigated. CONCLUSIONS: Daily variations of target position markedly reduced the TCP if small margins were used. Off-line correction of systematic errors can only partly compensate for these TCP reductions. The adequate number of treatment imaging days required for systematic error correction depends on the magnitude of the random component compared with the systematic component, and on the size of PTV margin used. For random components equal to or smaller than the systematic component, 3 consecutive treatment imaging days are estimated to be sufficient to gain most of the benefit from correction for current clinically used margins (6-10 mm); otherwise more days are required.

Humans↗
PubMed2003

Systematic reviews: a cross-sectional study of location and citation counts.

BACKGROUND: Systematic reviews summarize all pertinent evidence on a defined health question. They help clinical scientists to direct their research and clinicians to keep updated. Our objective was to determine the extent to which systematic reviews are clustered in a large collection of clinical journals and whether review type (narrative or systematic) affects citation counts. METHODS: We used hand searches of 170 clinical journals in the fields of general internal medicine, primary medical care, nursing, and mental health to identify review articles (year 2000). We defined 'review' as any full text article that was bannered as a review, overview, or meta-analysis in the title or in a section heading, or that indicated in the text that the intention of the authors was to review or summarize the literature on a particular topic. We obtained citation counts for review articles in the five journals that published the most systematic reviews. RESULTS: 11% of the journals concentrated 80% of all systematic reviews. Impact factors were weakly correlated with the publication of systematic reviews (R2 = 0.075, P = 0.0035). There were more citations for systematic reviews (median 26.5, IQR 12 - 56.5) than for narrative reviews (8, 20, P <.0001 for the difference). Systematic reviews had twice as many citations as narrative reviews published in the same journal (95% confidence interval 1.5 - 2.7). CONCLUSIONS: A few clinical journals published most systematic reviews. Authors cited systematic reviews more often than narrative reviews, an indirect endorsement of the 'hierarchy of evidence'.

Bibliometrics↗
PubMed2024

A research synthesis of humans, animals, and environmental compartments exposed to PFAS: A systematic evidence map and bibliometric analysis of secondary literature.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are a class of widely used anthropogenic chemicals. Concerns regarding their persistence and potential adverse effects have led to multiple secondary research publications. Here, we aim to assess the resulting evidence base in the systematic secondary literature by examining research gaps, evaluating the quality of reviews, and exploring interdisciplinary connections. METHODS: This study employed a systematic evidence-mapping approach to assess the secondary literature on the biological, environmental, and medical aspects of exposure to 35 fluorinated compounds. The inclusion criteria encompassed systematic reviews published in peer-reviewed journals, pre-prints, and theses. Comprehensive searches across electronic databases and grey literature identified relevant reviews. Data extraction and synthesis involved mapping literature content and narrative descriptions. We employed a modified version of the AMSTAR2 checklist to evaluate the methodological rigour of the reviews. A bibliometric data analysis uncovered patterns and trends in the academic literature. A research protocol for this study was previously pre-registered (osf.io/2tpn8) and published (Vendl et al., Environment International 158 (2022) 106973). The database is freely accessible through the interactive and user-friendly web application of this systematic evidence map at https://hi-this-is-lorenzo.shinyapps.io/PFAS_SEM_Shiny_App/. RESULTS: Our map includes a total of 175 systematic reviews. Over the years, there has been a steady increase in the annual number of publications, with a notable surge in 2021. Most reviews focused on human exposure, whereas environmental and animal-related reviews were fewer and often lacked a rigorous systematic approach to literature search and screening. Review outcomes were predominantly associated with human health, particularly with reproductive and children's developmental health. Animal reviews primarily focused on studies conducted in controlled laboratory settings, and wildlife reviews were characterised by an over-representation of birds and fish species. Recent reviews increasingly incorporated quantitative synthesis methodologies. The methodological strengths of the reviews included detailed descriptions of study selection processes and disclosure of potential conflicts of interest. However, weaknesses were observed in the critical lack of detail in reporting methods. A bibliometric analysis revealed that the most productive authors collaborate within their own country, leading to limited and clustered international collaborations. CONCLUSIONS: In this overview of the available systematic secondary literature, we map literature content, assess reviews' methodological quality, highlight data gaps, and draw research network clusters. We aim to facilitate literature reviews, guide future research initiatives, and enhance opportunities for cross-country collaboration. Furthermore, we discuss how this systematic evidence map and its publicly available database benefit scientists, regulatory agencies, and other stakeholders by providing access to current systematic secondary literature on PFAS exposure.

Bibliometrics↗