Health and Diseases in Populations Lecture

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Questions and Answers

What is the main purpose of a forest plot?

To compare the quality of different studies

To calculate the odds ratio in a meta-analysis

To identify the sources of evidence in a study

To display the estimated results from multiple studies

What is the name of the organization that provides a critical summary of randomized controlled trials?

World Health Organization

Cochrane Organization (correct)

National Institute of Health

American Medical Association

What is a problem that can occur in meta-analysis?

Heterogeneity between studies

Variable quality of the studies

Publication bias in selection of studies

All of the above (correct)

What is the term for the graphical display of estimated results from multiple studies?

Forest plot Signup and view all the answers

What is the main objective of evidence-based healthcare?

To base healthcare services and interventions on best available evidence Signup and view all the answers

What is a characteristic of a systematic review?

Explicit assumptions and transparent methodology Signup and view all the answers

Who is the person who criticized the medical profession for not organizing a critical summary of randomized controlled trials?

Archie Cochrane Signup and view all the answers

What is the percentage of weight for the study with the odds ratio of 1.12 (1.04,1.21)?

72.9 Signup and view all the answers

What is the purpose of a meta-analysis?

To facilitate the synthesis of a large number of study results Signup and view all the answers

What is a limitation of expert reviews in healthcare decision-making?

They are biased, subjective, and not reproducible Signup and view all the answers

What is the term for a review of multiple studies that provides a comprehensive summary of the results?

Systematic review Signup and view all the answers

What is the overall odds ratio in the forest plot?

1.11 Signup and view all the answers

What is a key aspect of a systematic review?

It is an extremely credible source of evidence Signup and view all the answers

What is the purpose of a systematic literature search in a systematic review?

To identify all relevant studies on a specific topic Signup and view all the answers

What is the difference between a systematic review and a meta-analysis?

A systematic review is an overview of primary studies, while a meta-analysis is a quantitative synthesis of the results of two or more primary studies Signup and view all the answers

What is the purpose of decision analyses in healthcare?

To evaluate the harms and benefits of a healthcare intervention Signup and view all the answers

Study Notes

Healthcare Services and Interventions

Healthcare services and interventions should be based on the best available evidence
Best available evidence comes from rigorously conducted research, including:
- Primary research studies (e.g. RCT)
- Literature reviews
- Decision analyses (e.g. harms and benefits, cost-effectiveness)

Systematic Reviews

A systematic review is a credible source of evidence that:
- Asks a clearly focused question
- Has explicit statements about:
  - Types of study
  - Types of participants
  - Types of interventions
  - Types of outcome measures
- Uses a systematic literature search
- Selects and appraises materials
- Synthesizes results (possibly including a meta-analysis)
A systematic review is explicit, transparent, and reproducible

Meta-Analysis

A meta-analysis is a quantitative synthesis of the results of two or more primary studies that:
- Address the same hypothesis
- Use the same methodology
The purpose of a meta-analysis is to:
- Facilitate the synthesis of a large number of study results
- Systematically collate study results
- Reduce problems of interpretation due to variations in sampling
- Quantify effect sizes and their uncertainty as a pooled estimate

Forest Plot

A forest plot is a graphical display of estimated results from multiple scientific studies addressing the same question
It shows the overall results, along with the results of each individual study

Example of Meta-Analysis

A meta-analysis of RCTs of the effect of aspirin in preventing death after myocardial infarction
The results of 7 studies are combined to show the overall effect of aspirin on mortality

Problems in Meta-Analysis

Heterogeneity between studies
Variable quality of the studies
Publication bias in selection of studies

Sources of Evidence

Systematic reviews are a key source of evidence in healthcare
Archie Cochrane, a pioneer in evidence-based medicine, emphasized the importance of organizing and summarizing RCTs by specialty or subspecialty

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Description

Review evidence-based healthcare and the role of systematic reviews in clinical practice. Learn to interpret Forest plots and overcome common difficulties in systematic reviews.