EBVM Toolkit 6: controlled trial checklist

Introduction

Critical appraisal is a process which is used to help you identify the strengths and weakness of a research paper.  Understanding how appropriate the study design is for the question you are seeking to answer, how well the study was carried out, and how good the reporting in the paper is helps you to assess whether the paper is likely to provide reliable evidence.  

This page is designed to help you appraise the report of a controlled trial.  Answering the questions will help you to reflect on how valid the results might be, how well reported they are and whether they are applicable to your local circumstances.

Controlled trial checklist

For each question think about whether the answer is yes, no or not sure and what your reasoning is for that answer.

1. Did the trial address a clearly focused issue?

Think about whether there is there a clear question. Can you identify the PICO?

2. Was the assignment of animals to treatments randomised?

Look for the term randomised and for details of how the randomisation was achieved. Remember that controlled trials will not all be randomised.

3. Were all of the animals who entered the trial properly accounted for at its conclusion?

Was follow up complete? Were animals analysed in the groups to which they were allocated?

4. Were animals and study personnel ‘blind’ to treatment including any study personnel who assessed outcomes?

Look for the terms blinding, double blind, or masking. For animal studies this may be less important for the animals but could be significant when for example an injection is compared to an oral product. In this case a so-called double-dummy design is ideal where animals receive both an injection and an oral product, one being active and the other placebo.

5. Were the groups similar at the start of the trial?

Important issues include age, severity of the condition, species, breed, possibly gender.

6. Aside from the experimental intervention, were the groups treated equally?

Is there any suggestion that the groups received different treatment other than what was planned?

7. How large was the treatment effect?

What outcomes were measured?

8. How precise was the estimate of the treatment effect?

Look for confidence intervals.

9. Can the results be applied to your practice?

Are the animals similar to your population? Does your setting differ significantly?

10. Were all clinically important outcomes considered?

Were the outcomes the ones you would choose? If not the trial may be less valuable.

11. Are the benefits worth the harms and costs?

This probably won’t be in the trial but a rough evaluation should be done to help you decide if you want to use this intervention in practice.

Try it out yourself

You could use the following paper to try out the questions:

Suputtamongkol, Y, et al. (2011) Efficacy and safety of single and double doses of ivermectin versus 7-day high dose albendazole for chronic strongyloidiasis. PLoS Neglected Tropical Diseases, 5(5):e1044. DOI: https://doi.org/10.1371/journal.pntd.0001044