How to analyse a clinical trial
Reviewed and revised 26 August 2015
OVERVIEW
- clinicians must be able to critically appraise clinical trials to determine their internal validity
- trials should adhere to the CONSORT statement (CONsolidated Standards of Reporting Trials)
- appraisal involves sequential pertinent information assessment
ASSESSMENT
Title
- should include blinding, randomisation and primary end point analysed
Abstract
- clear, transparent with accurate record of conduct and findings.
- objective
- trial design
- methods: participants, interventions, primary endpoints, randomization, blinding
- results: number randomized in each group, number analysed, result for each group and precision, adverse events or side effects.
- conclusion: general interpretation
- registration
- funding
Introduction
- scientific background and rationale for study
- discuss any current data and reason for equipoise
- present specific objectives or hypotheses
Methods
- describe trial design: parallel, multi-arm parallel, crossover, cluster
- type of randomisation
- allocation ratio
- eligibility criteria with reasons
- setting and location where data collected
- intervention with sufficient detail to allow replication (how and when administered)
- outcomes: primary and secondary (how and when assessed)
- changes to trial outcomes after commencement with reasons
- sample size calculation
- interim analyses and stopping triggers
- randomization: technique, type, allocation concealment mechanism, implemenation
- blinding
- similarity of intervention
- statistical methods for outcome assessment
- additional analyses (sub-group and adjusted analyses)
Flow diagram and reasons (CONSORT diagram)
- assessed for eligibility
- underwent randomization
- losses and exclusion
- assessed for primary outcome
Results
- recruitment and follow up
- reasons for stopping trial early
- base line data
- numbers analysed
- outcomes: primary and secondary with confidence intervals
- absolute and relative effect sizes
- pre-specified and subgroup analyses
- harms in each group
- intention to treat
Discussion
- limitations
- bias
- imprecision
- generalisability (external validity)
- interpretation of results
- balance of benefits and harms
- consideration and comparison of other relevant evidence
Other information
- registration number
- name of trial registry
- full trial protocol
- funding and other support
References and Links
LITFL
- CCC — How to conduct a clinical trial
- CCC — Early stopping of clinical trial
- CCC — How to analyse a clinical trial
Journal articles
- Ospina-Tascón GA, Büchele GL, Vincent JL. Multicenter, randomized, controlled trials evaluating mortality in intensive care: doomed to fail? Crit Care Med. 2008 Apr;36(4):1311-22. PMID: 18379260.
FOAM and web resources
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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