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PubMed1994

Rationale for systematic reviews.

Systematic literature reviews including meta-analyses are invaluable scientific activities. The rationale for such reviews is well established. Health care providers, researchers, and policy makers are inundated with unmanageable amounts of information; they need systematic reviews to efficiently integrate existing information and provide data for rational decision making. Systematic reviews establish whether scientific findings are consistent and can be generalised across populations, settings, and treatment variations, or whether findings vary significantly by particular subsets. Meta-analyses in particular can increase power and precision of estimates of treatment effects and exposure risks. Finally, explicit methods used in systematic reviews limit bias and, hopefully, will improve reliability and accuracy of conclusions.

Meta-Analysis as Topic↗

PubMed2003

Designing a quality improvement intervention: a systematic approach.

Most quality improvement or change management interventions are currently designed intuitively and their results are often disappointing. While improving the effectiveness of interventions requires systematic development, no specific methodology for composing intervention strategies and programmes is available. This paper describes the methodology of systematically designing quality of care improvement interventions, including problem analysis, intervention design and pretests. Several theories on quality improvement and change management are integrated and valuable materials from health promotion are added. One method of health promotion-intervention mapping-is introduced and applied. It describes the translation of knowledge about barriers to and facilitators of change into a concrete intervention programme. Systematic development of interventions, although time consuming, appears to be worthwhile. Decisions that have to be made during the design process of a quality improvement intervention are visualised, allowing them to serve as a starting point for a systematic evaluation of the intervention.

Decision Making, Organizational↗

PubMedDate not supplied

Delirium: effectiveness of systematic interventions.

The purpose of this paper was to review evidence related to the effectiveness of systematic interventions in preventing or detecting and treating delirium. The review process involved a systematic search of the literature on each topic, assessment of the validity of the studies retrieved and examination of their results. The literature search identified 10 studies on prevention and 7 studies on detection and treatment. A broad spectrum of systematic interventions appeared to be modestly effective in preventing delirium in young and old surgical patients but not elderly medical patients. Systematic detection and treatment programs and special nursing care appeared to add large benefits to traditional medical care in young and old surgical patients and modest benefits in elderly medical patients; however, it seemed that the more precise the target of the detection and treatment program, the greater the benefit.

Clinical Protocols↗

PubMed2003

How objective are systematic reviews? Differences between reviews on complementary medicine.

Systematic reviews are considered the most reliable tool to summarize existing evidence. To determine whether reviews that address the same questions can produce different answers we examined systematic reviews of herbal medicine, homeopathy, and acupuncture taken from a previously established database. Information on literature searching, inclusion criteria, selection process, quality assessment, data extraction, methods to summarize primary studies, number of included studies, results and conclusions was compared qualitatively. Seventeen topics (eight on acupuncture, six on herbal medicines, three on homeopathy) had been addressed by 2-5 systematic reviews each. The number of primary studies in the reviews varied greatly within most topics. The most obvious reason for discrepancies between the samples was different inclusion criteria (in thirteen topics). Methods of literature searching may have contributed with some topics but the equivalence of the searches was difficult to assess. Differences were frequently observed in other methodological aspects, in results and in conclusions. This analysis shows that, at least in the three areas examined, systematic reviews often differ considerably. Readers should be aware that apparently minor decisions in the review process can have major impact.

Clinical Trials as Topic↗

PubMed2002

Ultrasonic error compensation method to correct instrumental and systematic errors in volumetric flow measurements: a theoretical study.

A computational model has been developed to observe the effects of several instrumental parameters and systematic error sources on ultrasonic volumetric flow measurements in vessels using an error compensation method proposed previously by the authors. The effects of two essential instrumental parameters, the gate length and pulse duration, on two intermediate flow results and an optimal correction factor as a function of the beam width-to-vessel diameter ratio (BWR) have been studied under steady flow conditions. The corrected flow results under typical combinations of those parameters show that by proper selection of a correction factor, the proposed method can compensate for those systematic errors. If the estimated BWR is within +/- 0.1 of the actual BWR value, the systematic error can be limited to within 6.5%. The study also shows that the compensation method can effectively reduce the errors caused by other systematic error sources such as the system sensitivity and high-pass filter function, as well as misalignment of the ultrasound beam from the center of the vessel.

Blood Flow Velocity↗

PubMed2005

Statistical analysis of systematic errors in high-throughput screening.

High-throughput screening (HTS) is an efficient technology for drug discovery. It allows for screening of more than 100,000 compounds a day per screen and requires effective procedures for quality control. The authors have developed a method for evaluating a background surface of an HTS assay; it can be used to correct raw HTS data. This correction is necessary to take into account systematic errors that may affect the procedure of hit selection. The described method allows one to analyze experimental HTS data and determine trends and local fluctuations of the corresponding background surfaces. For an assay with a large number of plates, the deviations of the background surface from a plane are caused by systematic errors. Their influence can be minimized by the subtraction of the systematic background from the raw data. Two experimental HTS assays from the ChemBank database are examined in this article. The systematic error present in these data was estimated and removed from them. It enabled the authors to correct the hit selection procedure for both assays.

Algorithms↗

PubMed2002

Conducting systematic reviews of diagnostic studies: didactic guidelines.

BACKGROUND: Although guidelines for critical appraisal of diagnostic research and meta-analyses have already been published, these may be difficult to understand for clinical researchers or do not provide enough detailed information. METHODS: Development of guidelines based on a systematic review of the evidence in reports of systematic searches of the literature for diagnostic research, of methodological criteria to evaluate diagnostic research, of methods for statistical pooling of data on diagnostic accuracy, and of methods for exploring heterogeneity. RESULTS: Guidelines for conducting diagnostic systematic reviews are presented in a stepwise fashion and are followed by comments providing further information. Examples are given using the results of two systematic reviews on the accuracy of the urine dipstick in the diagnosis of urinary tract infections, and on the accuracy of the straight-leg-raising test in the diagnosis of intervertebral disc hernia.

Diagnostic Techniques and Procedures↗

PubMed2003

The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews.

BACKGROUND: In the era of evidence based medicine, with systematic reviews as its cornerstone, adequate quality assessment tools should be available. There is currently a lack of a systematically developed and evaluated tool for the assessment of diagnostic accuracy studies. The aim of this project was to combine empirical evidence and expert opinion in a formal consensus method to develop a tool to be used in systematic reviews to assess the quality of primary studies of diagnostic accuracy. METHODS: We conducted a Delphi procedure to develop the quality assessment tool by refining an initial list of items. Members of the Delphi panel were experts in the area of diagnostic research. The results of three previously conducted reviews of the diagnostic literature were used to generate a list of potential items for inclusion in the tool and to provide an evidence base upon which to develop the tool. RESULTS: A total of nine experts in the field of diagnostics took part in the Delphi procedure. The Delphi procedure consisted of four rounds, after which agreement was reached on the items to be included in the tool which we have called QUADAS. The initial list of 28 items was reduced to fourteen items in the final tool. Items included covered patient spectrum, reference standard, disease progression bias, verification bias, review bias, clinical review bias, incorporation bias, test execution, study withdrawals, and indeterminate results. The QUADAS tool is presented together with guidelines for scoring each of the items included in the tool. CONCLUSIONS: This project has produced an evidence based quality assessment tool to be used in systematic reviews of diagnostic accuracy studies. Further work to determine the usability and validity of the tool continues.

Bias↗

PubMed2006

Economics methods in Cochrane systematic reviews of health promotion and public health related interventions.

BACKGROUND: Provision of evidence on costs alongside evidence on the effects of interventions can enhance the relevance of systematic reviews to decision-making. However, patterns of use of economics methods alongside systematic review remain unclear. Reviews of evidence on the effects of interventions are published by both the Cochrane and Campbell Collaborations. Although it is not a requirement that Cochrane or Campbell Reviews should consider economic aspects of interventions, many do. This study aims to explore and describe approaches to incorporating economics methods in a selection of Cochrane systematic reviews in the area of health promotion and public health, to help inform development of methodological guidance on economics for reviewers. METHODS: The Cochrane Database of Systematic Reviews was searched using a search strategy for potential economic evaluation studies. We included current Cochrane reviews and review protocols retrieved using the search that are also identified as relevant to health promotion or public health topics. A reviewer extracted data which describe the economics components of included reviews. Extracted data were summarised in tables and analysed qualitatively. RESULTS: Twenty-one completed Cochrane reviews and seven review protocols met inclusion criteria. None incorporate formal economic evaluation methods. Ten completed reviews explicitly aim to incorporate economics studies and data. There is a lack of transparent reporting of methods underpinning the incorporation of economics studies and data. Some reviews are likely to exclude useful economics studies and data due to a failure to incorporate search strategies tailored to the retrieval of such data or use of key specialist databases, and application of inclusion criteria designed for effectiveness studies. CONCLUSION: There is a need for consistency and transparency in the reporting and conduct of the economics components of Cochrane reviews, as well as regular dialogue between Cochrane reviewers and economists to develop increased capacity for economic analyses alongside such reviews. Use of applicable economics methods in Cochrane reviews can help provide the international context within which economics data can be interpreted and assessed as a preliminary to full economic evaluation.

Clinical Protocols↗

PubMed2002

Systematic reviews in rehabilitation for stroke: issues and approaches to addressing them.

OBJECTIVES: To describe the problems encountered when undertaking systematic reviews of rehabilitation and to give advice to reviewers about ways of addressing these issues. BACKGROUND: Evidence-based practice has become established as a way of linking clinical practice with research evidence. The most robust evidence is usually considered to be that from randomized controlled trials, and from systematic reviews of these trials. However, most reviews have focused on drug and surgical interventions, and few reviews have been produced in the field of rehabilitation. This may be due to the unique difficulties that are posed by reviews in this area. EXPERIENCE OF SYSTEMATIC REVIEWS IN APHASIA: We describe the challenges that occurred when carrying out systematic reviews of speech and language therapy for aphasia following stroke, and of ways to deliver rehabilitation services to people who have suffered a stroke. Issues arose at all stages of the reviews and included: using expertise; planning the review; defining the health care problem, patients, outcomes and interventions of interest; searching for, interpreting and synthesizing the results of the studies identified; and deriving implications from the review. Suggestions made to address these challenges include: developing a suitable team of reviewers; using inclusive and broad criteria for inclusion of trials to a review; developing appropriate search strategies; and using caution in arriving at conclusions. It is important to be explicit about decisions made during the review process concerning how to handle the challenges. Practical advice about carrying out reviews in the field of stroke rehabilitation is likely to be helpful to reviewers of other rehabilitative interventions. There are likely to be relatively few studies available for such reviews, and limitations in drawing specific practical conclusions. Such undertakings are, however, useful in setting the agenda for further research.

Humans↗

PubMed2005

Evidence of the efficacy of occupational therapy in different conditions: an overview of systematic reviews.

OBJECTIVE: To summarize the research evidence available from systematic reviews of the efficacy of occupational therapy (OT) for practitioners, researchers, purchasing organizations and policy-makers. DATA SOURCE: The search for systematic reviews was conducted in PubMed and the Cochrane Library (October 2004). METHODS: The reviews included were those that utilized a systematic search for evidence with regard to OT for specific patient groups. Data were summarized for patient group, interventions, outcome domains, type of study designs included, method of data synthesis and conclusions. RESULTS: Fourteen systematic reviews were included. Three reviews related to rheumatoid arthritis, four reviewed stroke and four focused on elderly people. Reviews of Parkinson's disease, multiple sclerosis, Huntington's disease, cerebral palsy and mental illnesses were also identified. The reviews of rheumatoid arthritis, stroke and elderly people showed evidence of the efficacy of OT in increasing functional abilities. Positive results were presented for quality of life and social participation in elderly people and stroke respectively. The efficacy of OT in all other patient groups is unknown due to insufficient evidence. CONCLUSION: This summary shows that elderly people and people with stroke or rheumatoid arthritis can expect to benefit from comprehensive OT. Evidence of the efficacy of specific interventions is sparse and should be addressed in future research. The evidence that does exist should be incorporated into OT practice.

Aged↗

PubMed2006

Uncertainty about nest position influences systematic search strategies in desert ants.

Foraging desert ants return to their starting point, the nest, by means of path integration. If the path-integration vector has been run off but the nest has not yet been reached, the ants engage in systematic search behavior. This behavior results in a system of search loops of ever increasing size and finally leads to a search density profile peaking at the location where the path integration system has been reset to zero. In this study we investigate whether this systematic search behavior is adapted to the uncertainty resulting from the preceding foraging run. We show first that the longer the distances of the foraging excursions, the larger the errors occurring during path integration, and second that the ants adapt their systematic search strategy to their increasing uncertainty by extending their search pattern. Hence, the density of the systematic search pattern is correlated with the ants' confidence in their path integrator. This confidence decreases with increasing foraging distances.

Animals↗

PubMedDate not supplied

Evidence of evidence-based health policy: the politics of systematic reviews in coverage decisions.

U.S. policymakers are making greater use of findings from systematic reviews, the principal product of the discipline of research synthesis. This paper summarizes the methodology and availability of systematic reviews and the brief history of their introduction to policymakers in the public and private sectors and health professionals in the United States. Then, as a case study, the paper describes how officials in a consortium of states are using systematic reviews to inform decisions about coverage for pharmaceuticals. Finally, it explores the prospects for wider use of systematic reviews by policymakers.

Decision Making↗

PubMed2004

Retroposon mapping in molecular systematics.

Advances in genome sciences are demonstrating the dynamic nature of noncoding DNA regions, which are comprised largely of repetitive elements with no apparent function. Retroposons are one class of mobile genetic elements that amplify and move about the genome via a copy-and-paste mechanism that employs an RNA intermediate. Short and long interspersed elements (SINEs and LINEs, respectively) are types of retroposons of particular interest because of their active role in shaping the architecture of genomes and their diagnostic value as evolutionary markers for studies of phylogeny and population biology. Although the use of SINEs and LINEs for molecular systematic studies is proliferating, a comprehensive laboratory protocol that explicitly outlines how to isolate and characterize retroposons for systematic studies in a detailed, step-by-step fashion has been lacking. The present chapter addresses this gap in the literature by focusing on the strategy for isolating new SINEs from a genomic library, the screening process, the sequencing and characterization of clones into subfamilies, quantification of copy number in host taxa, and the critical diagnosis of phylogenetically informative SINE and LINE insertion patterns. Practical limits to the method are discussed in relation to sampling design, systematic character theory, and the empirical distribution of elements observed in eukaryotic lineages. Major steps in the experimental process are illustrated with case examples from a diversity of taxonomic groups and by published results in the molecular biology and systematics literature.

Animals↗

PubMed2001

Models for combining random and systematic errors. assumptions and consequences for different models.

A series of models for handling and combining systematic and random variations/errors are investigated in order to characterize the different models according to their purpose, their application, and discuss their flaws with regard to their assumptions. The following models are considered 1. linear model, where the random and systematic elements are combined according to a linear concept (TE = absolute value(bias) + z x sigma), where TE is total error, bias is the systematic error component, sigma is the random error component (standard deviation or coefficient of variation) and z is the probability factor; 2. squared model with two sub-models of which one is the classical statistical variance model and the other is the GUM (Guide to Uncertainty in Measurements) model for estimating uncertainty of a measurement; 3. combined model developed for the estimation of analytical quality specifications according to the clinical consequences (clinical outcome) of errors. The consequences of these models are investigated by calculation of the functions of transformation of bias into imprecision according to the assumptions and model calculations. As expected, the functions turn out to be rather different with considerable consequences for these types of transformations. It is concluded that there are at least three models for combining systematic and random variation/errors, each created for its own specific purpose, with its own assumptions and resulting in considerably different results. These models should be used according to their purposes.

Algorithms↗

PubMed2004

Distance-restrained docking of rifampicin and rifamycin SV to RNA polymerase using systematic FRET measurements: developing benchmarks of model quality and reliability.

We are developing distance-restrained docking strategies for modeling macromolecular complexes that combine available high-resolution structures of the components and intercomponent distance restraints derived from systematic fluorescence resonance energy transfer (FRET) measurements. In this article, we consider the problem of docking small-molecule ligands within macromolecular complexes. Using simulated FRET data, we have generated a series of benchmarks that permit estimation of model accuracy based on the quantity and quality of FRET-derived distance restraints, including the number, random error, systematic error, distance distribution, and radial distribution of FRET-derived distance restraints. We find that expected model accuracy is 10 A or better for models based on: i), > or =20 restraints with up to 15% random error and no systematic error, or ii), > or =20 restraints with up to 15% random error, up to 10% systematic error, and a symmetric radial distribution of restraints. Model accuracies can be improved to 5 A or better by increasing the number of restraints to > or =40 and/or by optimizing the distance distribution of restraints. Using experimental FRET data, we have defined the positions of the binding sites within bacterial RNA polymerase of the small-molecule inhibitors rifampicin (Rif) and rifamycin SV (Rif SV). The inferred binding sites for Rif and Rif SV were located with accuracies of, respectively, 7 and 10 A relative to the crystallographically defined binding site for Rif. These accuracies agree with expectations from the benchmark simulations and suffice to indicate that the binding sites for Rif and Rif SV are located within the RNA polymerase active-center cleft, overlapping the binding site for the RNA-DNA hybrid.

Binding Sites↗

PubMedDate not supplied

Systematic reviews on leptospirosis.

OBJECTIVES: To find the existing clinical evidence on interventions for leptospirosis. The objective is to evaluate the effectiveness and safety of any intervention on leptospirosis through systematic reviews of randomized controlled trials (RCTs). DATA SOURCE: The sources of studies used (where there were no limitations concerning language, date, or other restrictions) were: EMBASE, LILACS, MEDLINE, the Cochrane Controlled Clinical Trials Database, and the Cochrane Hepato-Biliary Group Randomized Trials register. SELECTION OF STUDIES TYPE OF STUDY: All systematic reviews of randomized controlled trials. PARTICIPANTS: patients with clinical and/or laboratorial diagnosis of leptospirosis, and subjects potencially exposed to leptospirosis as defined by the authors INTERVENTIONS: any intervention for leptospirosis (as antibiotics or vaccines for prevention or treatment). DATA COLLECTION: The assessment will be independently made by the reviewers and cross-checked. The external validity was assessed by analysis of: studies, interventions, and outcomes. DATA SYNTHESIS: Located 163 studies using the search strategy described above, at the electronic databases above. Only 2 hits were selected, which are protocols of systematic reviews of Cochrane Collaboration, and not full reviews. One of the protocols evaluates antibiotics for treatment, and the other evaluates antibiotics for prevention of leptospirosis. CONCLUSIONS: There were not complete systematic reviews on interventions for leptospirosis. Any interventions for leptospirosis, such as prevention and treatment remains unclear for guidelines and practice.

Databases, Bibliographic↗

PubMed1988

Identifying reinforcers for persons with profound handicaps: staff opinion versus systematic assessment of preferences.

We evaluated a systematic means of determining stimulus preferences among seven profoundly handicapped persons. Preferences were determined by observing student approach responses to individual stimuli. Results indicated that there were differential stimulus preferences across the multiply handicapped participants. However, results of the systematic assessment did not coincide with the results of a more traditional, caregiver-opinion method of assessing student preferences. A second experiment was then conducted with five participants to evaluate whether stimuli that were assessed to consistently represent preferences would function as reinforcers in skill training programs. Results indicated that stimuli that were systematically assessed to represent student preferences typically functioned as reinforcers when applied contingently. However, preferred stimuli as reflected by caregiver opinion did not function as reinforcers unless those stimuli were also preferred on the systematic assessment. Results are discussed in terms of assisting profoundly handicapped persons by (a) improving the effectiveness of training programs by increasing the likelihood of using stimuli that have reinforcing value and (b) increasing the overall quality of life by providing preferred stimuli in the routine living environment.

Adolescent↗