Table 1

Breakdown of key considerations used to determine IDEAL stage

Characteristics of reportsKey issues addressed and content itemsKey milestones for stage completion
Idea (1)One or very few reports
Appears to be the earliest or near earliest report
Only case reports or very small case series
States that this is first use in humans
Detailed technical description
Reports an intervention not previously used in human
Development (2a)Small number of reports
Reports from one or a few centres
All reports have small number of patients
Nearly all reports are case
Safety of procedure
Short-term outcomes
Discusses indications
Discusses technical detail and may describe modifications
Content and nature of reports suggest intervention technique has reached stability
Exploration (2b)Increasing number of
Patients per report
Centres involved
Some prospective collaborative studies (registries, audits, databases)
Discusses procedural quality
Discusses learning curves
Comparison of outcomes with standard treatment
Calls for an RCT to be done
Reports suggest that consensus has been reached on optimal technique, indications and outcome measures
Assessment (3)Reports of multicentre RCTs
Quasi-experimental designs
Stepped-wedge designs
Case-matching studies
Analysis of large data sets with risk adjustment
Compares procedure with standard treatmentReports document a high-quality RCT or other valid experimental comparison of the intervention compared with the current standard of care
Long-term (4)Long-term cohort studies
Retrospective case series
Registries and databases
Analyses of large administrative data sets
No recent RCTs
Reports long-term outcomes
Identifies rare outcomes
May analyse risk or prognostic factors
May report on changing indications
Ongoing reports of
Late or rare outcomes
Which patients benefit most
Whether indications are changing
Variation in performance
  • RCT, randomised controlled trial.