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Systematic Reviews.

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Presentation on theme: "Systematic Reviews."— Presentation transcript:

1 Systematic Reviews

2 What is systematic review?
- Well documented of intervention research Scientific methodology reduced systematic errors (biases) reduced random errors (by chance) - Provide more objective, comprehensive view


4 Why are systematic reviews important?
1. Health personnel need updated information 2. Textbooks are out of date 3. Too much information (good and bad) 4. Journals are disorganized and limited 5. Knowledge and performance deteriorate

5 Advantages of systematic reviews
Inform clinical decision making - provide strong evidence regarding benefits or harms of a particular intervention Highlight area requiring further primary research

6 What’s different about a systematic review?
designed to minimise bias explicit and reproducible methodology regularly updated (Cochrane) aim to be comprehensive and reliable Traditional methodology not transparent different reviewers reach conclusions become out of date may not be comprehensive or accurate

7 Key features of a systematic review
clearly stated objectives pre-defined eligibility criteria explicit, reproducible methodology a systematic research an assessment of the validity of the findings of the included studies systematic presentation and synthesis of the findings of the included studies

8 Research synthesis Systemic reviews ± Meta-analysis

9 Step in conducting a research synthesis
Formulate review question Define inclusion and exclusion criteria (studies, participants and outcomes) Locate studies Select studies Assess study quality Extract data Analyze and present results Interpret results

10 Question: specify a clearly focus
Population (group to whom the intervention will apply) Intervention (the therapy, treatment or preventive policy to be carried out) Comparison (what will the intervention be compared against; alternative intervention vs. placebo or no intervention Outcomes (what to measure, what is important)

11 Example comparison To assess the effectiveness of interventions (which may include placebo or no treatment) for the treatment of oral mucositis, or its associated pain, for patients with cancer receiving chemotherapy and/or radiotherapy population intervention Outcomes: mucosotis at different levels of severity, oral pain scores, amount of analgesia, stay in hospital (days), cost of oral care etc. Study design: only randomized, controlled trials were eligible for the review

12 Quality Bias selection bias (non random differences between the people) attrition bias (more participants drop out of one arm of experiment) performance bias (those receiving intervention are aware) detection bias (assessing outcomes are aware)


14 Search strategy several electronic databases (including the Cochrane Library) check through the reference lists of included studies relevant reviews letter to relevant pharmaceutical companies experts in the field asking about unpublished or ongoing work hand searching of relevant journals or conference abstracts translation of foreign-language articles

15 Quality assessment Data extraction Undertaken independently by two reviewers

16 Quality of Evidence Ia. Research synthesis of randomized controlled trial (RCT) Ib. At least one properly designed RCT IIa. At least one well designed controlled without randomization IIb. At least one well-designed cohort study III. Evidence obtained from case control or descriptive studies IV. Opinion of respected

17 Critically appraising review
What are the review’s objectives? Well defined questions (population, intervention/control, outcomes) How comprehensive was the search strategy? Effort to search What were the inclusion/exclusion criteria? Clearly stated and appropriate How was the validity of the primary studies assessed? How were data extracted from the primary studies? Are the characteristics of the included studies clearly displayed? A table showing the study characteristics of each included primary study Does the review examine difference/similarities between the included studies and their results? Check heterogeneity between studies What the synthesis of the data carried out appropriately? Whether the data pooled qualitatively or statistically Were the results interpreted appropriately? Any conclusions, implications for research or practice should follow on logically from the results.

18 Where can find systematic review?
The Cochrane Database of Systematic Reviews (CDSR) The Database of Abstracts of Reviews of Effectiveness (DARE) produced by the NHS Centre for Reviews and Dissemination (CRD)



















37 How to prepare Cochrane protocol

38 Rationale for protocols
Minimize the potential for bias in the review process Promotes transparency of methods and processes Reduces the potential for duplication Allows peer review of the planned methods Protocols for Cochrane reviews are published before the completed systematic review in the Cochrane Database of Systematic Reviews (CDSR)

39 Format of a Cochrane review
Easy to find the results of research assess the validity, applicability and implications of those results. Guide the review authors to report their work explicitly and concisely and minimizing the effort required. Facilitate the electronic publication and maintenance of reviews.

40 Sections of a protocol for a Cochrane review
Title Protocol information Authors Contact person Dates What’ new History Background: Description of the condition, intervention, why it’s important to do this review Objectives Methods: criteria to select studies, search methods for identification of studies, data collection and analysis

41 Sections of a protocol for a Cochrane review
Acknowledgements References Tables and figures Additional tables Figures

42 Sections of a Cochrane review
Title Review information - Authors - Contact person - Dates - What’ new - History Abstract Background Objectives Search strategy Data collection and analysis Results Author’s conclusion Plain language summary Plain language title Summary text

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