What is it? Why is it important?

Study outcomes/endpoints are variables measured during the conduct of a study to address different aspects of a research question(s).

  • The primary outcome – used to determine whether an intervention has the intended effect
  • Other or not-primary outcomes believed to be informative, but not directly used to answer the main research question

 

Not-primary outcomes/endpoints are generally named

  • Secondary: are additional variables monitored during study conduct with the aim to support the interpretation of the primary outcome/endpoint
  • Safety: are adverse events or negative effects experienced by participants during study conduct. These outcomes are crucial to evaluate the safety and tolerability of an intervention
  • Exploratory: include measurements researchers believe to be informative to generate hypotheses or explore potential effects; they are usually less definitive than secondary outcomes/endpoints

More

Safety outcomes can include a wide range of effects, from mild discomfort or side effects to severe complications or even death. Common safety outcomes assessed in clinical studies may notably include Serious adverse events (SAEs), Adverse events (AEs), Adverse drug reactions (ADRs).

What do I need to do?

As a SP-INV:

  • Define the study primary and not-primary outcome(s)/endpoint(s) during the concept phase of your study (e.g. at the time when selecting your study design)
  • Ensure outcome(s)/endpoint(s) match with the research question.

 

Keep in mind that the study is powered to detect a clinically meaningful effect on the primary endpoint, but may not have sufficient statistical power to detect differences in other endpoints. Therefore:

  • Analyses of secondary outcomes should be interpreted with caution, as they are primarily supportive or exploratory rather than confirmatory
  • Effect estimates and their confidence intervals may be more informative and appropriate than formal statistical significance testing based on p-values

Where can I get help?

Your local Research Support Centre↧ can assist you with experienced staff regarding this topic

  • Basel, Departement Klinische Forschung (DKF), dkf.unibas.ch

  • Lugano, Clinical Trials Unit (CTU-EOC), ctueoc.ch

  • Bern, Department of Clinical Research (DCR), dcr.unibe.ch

  • Geneva, Clinical Research Center (CRC), crc.hug.ch

  • Lausanne, Clinical Research Center (CRC), chuv.ch

  • St. Gallen, Clinical Trials Unit (CTU), h-och.ch

  • Zürich, Clinical Trials Center (CTC), usz.ch

Useful External Links

COMET initiative - to standardize outcomes for clinical trials

References

ICH GCP E6(R3) – see in particular guidelines

  • Principles of ICH GCP Nr. 8.2 The scientific objective of a study should be clear
  • 3.9.8 Endpoint assessment
  • 3.11.4 / 3.11.4.3 Monitoring of trial endpoints
  • Appendix B. 4 Trial design - 4.1 Primary / secondary endpoints statement

ICH Topic E8(R1) General considerations for clinical studies - see in particular

  • 5.5 Methods to reduce bias

ICH Topic E9(R1) Statistical Principles for Clinical Trials – see in particular

  • 2.2.2 Primary and secondary variables
  • 2.2.4 Global assessment variables
  • 2.2.5 Multiple Primary Variables
  • 2.2.7 Categorised variables
Abbreviations
  • ICH – International Council for Harmonisation
  • ICH-GCP – International Council for Harmonisation - Good Clinical Practice
  • SP-INV – Sponsor Investigator
Basic ↦ Statistic Methodology ↦ Research Question ↦ Outcome Endpoint Description
Study
Basic

Provides some background knowledge and basic definitions

Basic Monitoring
Concept

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Statistic Methodology
Concept Drug or Device
Development

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Drug or Device
Set-Up

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Ethics and Laws
Set-Up Statistic Methodology
Set-Up Quality and Risk
Set-Up Drug or Device
Conduct

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Statistic Methodology
Conduct Drug or Device
Completion

Starts with last study visit completed

Ends after study publication and archiving

Completion Drug or Device
Current Path (click to copy): Basic ↦ Statistic Methodology ↦ Research Question ↦ Outcome Endpoint Description