Appraise the Evidence
Critical analysis is a way or examining the research to assess its validity and relevance. It is an essential step in making sense of the research evidence. You should ask the following questions:
Critical Appraisal Tools
Below is a list of critical appraisal tools used in evidence-based medicine:
The following terminology is important in critical appraisal and will be helpful to determine the validity of research. Additianal terms can be found in the Centre for Evidence Based Medicine Glossary
Whether a particular treatment or form of care that was demonstrated as effective in a trial could be expected to provide the same effect for an individual or group in a specific clinical or population setting
Any influence that may cause a distortion of results in a study and undermine validity. Bias may originate from various sources, such as allocation of patients, measurement, interpretation, publication, and review of data
|Confidence interval (CI)||
Confidence Interval (CI) is the interval within which the population parameter (the ‘true’ value) is expected to lie with a given degree of certainty, for example 95%
External validity is the degree to which the results of a clinical study can be applied to a setting other than the one studied.
The ability to reliably apply the results of a study to other populations, based on the characteristics of the subjects, size of the sample, the setting, and trustworthiness of the study
A method of analysis for randomized trials in which all patients randomly assigned to one of the treatment groups is analysed with that assigned group, regardless of whether or not they completed or received the treatment.
A study has internal validity if it is free from bias or systematic error and the results seen are due only to the intervention.
p value is the probability that a particular result would have happened by chance.
Ability to detect a difference between two experimental groups if a difference exists.
|Relative risk (RR)||
Relative Risk (RR) is the ratio of the probability of outcome in the treatment and control groups. This expresses the risk of the probable outcome in the treatment group relative to that in the control group.
The extent of the measurement of trustworthiness of the results.
Learn more about
Confidence Intervals & p values
Confidence Intervals and p values, published by Hayward Medical Communication
Numbers needed to treat
Numbers needed to treat, BMJ 2010; 341
How to calculate numbers needed to treat (YouTube 3:48)
How to calculate relative risk (YouTube 3:14)
Odds and odds ratios, BMJ 2013; 347
How to calculate an odds ratio (YouTube 3:17)
Intention to treat
Intention-to-treat analysis, BMJ 2013; 346
How to read a forest plot in a meta-analysis, BMJ 2015; 351
How to interpret a forest plot (YouTube 5:32)