School of Population Health


2013 Evidence based practice and critical appraisal


Presentations and papers

In this section we provide a series of downloadable presentations on the EPIQ approach to evidence-based practice and critical appraisal and a paper we have published on the GATE approach to critical appraisal. 

Critically appraised topics (CATs) checklists for quantitative studies (updated February 2013):

In this section we provide updated (2013) versions of our CAT checklists. The previous versions can be found on the 2011 page.

The new GATE CAT forms are now presented as MS Word documents rather than MS Excel documents, however the original calculator in the Excel version has been retained as a 1-page GATE Calculator. Each GATE CAT (MS Word) has an accompanying GATE calculator (MS Excel). We are also developing 1-page GATE CATs as writeable pdfs for rapid critical appraisals. To date we have completed one for RCTs/Cohort/Cross-sectional Studies and one for Diagnostic test Accuracy Studies.

GATE CATs and GATE calculators are designed to enable users to model the five steps of evidence-based practice and the electronic forms make it easy to keep a record of the process. Users fill in the yellow-coloured fields of the CATs. Most of yellow fields have prompt questions that should be deleted after addressing the questions. The format of each GATE CAT is as follows:

  • Page 1 documents the clinical /practice scenario, the question asked (Step 1) and the search strategy and search results (Step 2).
  • Page 2 documents the first part of critical appraisal (Step 3a) which involves hanging the study on the GATE frame. The accompanying GATE Calculators should be completed with Page 2 of the GATE CAT. If you key the main study numbers into the GATE calculator, it automatically calculates the relevant outputs including: risk, risk ratios, risk differences and NNTs, sensitivity, specificity as well as 95% confidence intervals for all estimates (note: the systematic review checklist does not include a calculator).
  • Pages 3-5 document the second part of critical appraisal (Step 3b) which is to assess the quality of the study (internal & external validity, precision and power).
  • Page 6 documents the integration and application of evidence (Step 4) and personal and clinical audit (Step 5).

1. Evidence about Interventions (from RCTs, Cohort & Cross-sectional Studies)

  • GATE CAT for Intervention Studies: this MS Word form is designed for using evidence from RCTs and non-randomised cohort and cross-sectional studies to inform questions about the effectiveness of interventions.
  • GATE Calculator for Intervention Studies: this MS Excel form is designed to accompany the GATE CAT for Intervention Studies.
  • GATE-lite for Intervention Studies: the writeable pdf is designed as a 1-page form that combines the GATE CAT and GATE Calculator. It is often necessary to use the results from the GATE calculator to complete GATE-lite if the paper being appraised does not include all the relevant results.

2. Evidence about Diagnostic Test Accuracy

  • GATE CAT for Diagnostic Test Accuracy Studies: this MS Word form is designed for using evidence from cross-sectional studies to inform questions about the accuracy of diagnostic tests.
  • GATE Calculator for Diagnostic Test Accuracy Studies: this MS Excel form is designed to accompany the GATE CAT for Diagnostic Test Accuracy Studies. The form now includes a Likelihood Ratio nomogram linked the the GATE Calculator. The default display on the nomogram is generated from the numbers entered into the GATE calculator, however is also possible to modify the pre-test probability (and the LRs if appropriate) to illustrate the impact of applying the test in different populations.
  • GATE-lite for Diagnostic Test Accuracy Studies: the writeable pdf is designed as a 2-page form (plus a glossary) that combines the GATE CAT and GATE Calculator. It is often necessary to use the results from the GATE calculator to complete GATE-lite if the paper being appraised does not include all the relevant results. The second page of this GATE-lite (after the glossary) is a LR nomogram that really helps users to make sense of the results from diagnostic studies.

3. Evidence about Risk Factors & Prognosis (from Cohort & Cross-sectional Studies)

  • GATE CAT for Risk Factor or Prognostic Studies: this MS Word form is designed for using evidence from cohort and cross-sectional studies to inform questions about the effects of risk factors or the power of prognostic markers.
  • GATE Calculator for Risk Factor or Prognostic Studies: this MS Excel form is designed to accompany the GATE CAT for Risk Factor or Prognostic Studies.
  • GATE-lite for Risk Factor or Prognostic Studies: the writeable pdf is designed as a 1-page form that combines the GATE CAT and GATE Calculator. It is often necessary to use the results from the GATE calculator to complete GATE-lite if the paper being appraised does not include all the relevant results. The GATE-lite for intervention studies can also be used for risk factor and prognostic studies.

4. Evidence from Case-Control Studies

Case-control studies are used to investigate questions about interventions, risk factors and prognosis. However they are sufficiently different from other study designs to warrant a separate CAT and calculator.

5. Evidence from Systematic Reviews

The GATE CAT for Systematic Reviews has been designed for appraising reviews of intervention studies, whatever the type of study. There is no GATE calculator or GATE-lite for Systematic Reviews. The CAT uses a simple framework 'FAITH' that was designed by Rod Jackson from the EPIQ team to help with the appraisal.