3. Extracting Data From Articles

 Read the collected articles to understand the background and key points, and highlight the relevant findings that answer your query.

Establish:

• Paper type – systematic review, randomised controlled trial etc
  
• Does the paper meet your inclusion / exclusion strategy? – for example, dated information, adults not children
  
• What is the clinical question the paper addresses?
  
• Patient numbers
  
• Key results and outcomes – actual figures are useful here
  
• P values and confidence intervals – what statistical tests have been performed?
  
• Assess the methodology (see below)
  
• GRADE the level of evidence (to follow)

Assessing the Methodology

The methodology of the paper must be considered before papers are included. The strategies differ slightly between systematic reviews and randomised controlled trials.

Quality criteria for systematic studies

• Were the questions and methods clearly stated?
• Was the search method comprehensive and the methodology described?
• Were explicit methods used to determine which studies were included in the review?
• Was the methodological quality of primary studies assessed?
• Was the selection and assessment of primary studies reproducible and free from bias?
• Were differences in individual study results adequately explained?
• Were the results of primary studies combined appropriately?
• Were the reviewers' conclusions supported by data cited?

• Were the setting and study patients clearly described?
• Was assignment randomised and similarity between groups documented?
• Was allocation to study groups adequately concealed from patients and investigators, including blind assessment of outcome?
• Were all clinically relevant outcomes reported?
• Were > 80% of patients who entered the study accounted for at its conclusion?
• Were they analysed in the groups to which they were randomised (intention to treat)?
• Were both statistical and clinical significance considered?

• Were the recruitment setting, diagnostic criteria, disease severity, co-morbidity and demographic details documented?
• Was the referral pattern described?
• Referral or diagnostics access bias avoided?
• Was an adequate follow up rate achieved?
• Were > 80% patients entered accounted for in results and clinical status known?
• Were objective outcome criteria developed and used?
• Was outcome assessment blind?
• Was adjustment for extraneous prognostic factors carried out?

» Part 4: Evaluating the evidence

» Back to reviewer's toolkit