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How real is intention-to-treat (ITT) analysis in non-interventional post authorization safety studies? We can do
Victor A Kiri1, Gilbert MacKenzie
1Peri-Approval, Clinical Research Services, PAREXEL International, Uxbridge, UK. Victor.Kiri@PAREXEL.com
Current Drug Safety
|May 16, 2009
Summary
Cohort studies using intention-to-treat (ITT) may misestimate drug effects. Alternative designs like nested case-control are explored for more accurate post-authorization safety studies.
Area of Science:
- Epidemiology
- Pharmacovigilance
- Biostatistics
Background:
- Cohort studies with intention-to-treat (ITT) analysis offer simplicity but may fail to capture time-varying treatment effects accurately.
- This can lead to exposure misclassification, under-estimation of effects, and irreproducible conclusions in real-world drug use scenarios.
- Accurate reflection of clinical practice is crucial for epidemiologic safety studies.
Purpose of the Study:
- To evaluate the limitations of intention-to-treat (ITT) in cohort studies for post-authorization safety evaluations.
- To present alternative study designs that may better reflect real-world drug use and mitigate biases.
- To provide an overview of advanced designs for prospective safety studies.
Main Methods:
- The study reviews the intention-to-treat (ITT) approach in cohort designs.
- It discusses the limitations of ITT, including potential for effect under-estimation and exposure misclassification.
- It introduces and overviews counter-matched nested case-control, case-crossover, case-in-time, case series, and case-cohort designs.
Main Results:
- Standard cohort ITT may not adequately estimate time-varying treatment effects, potentially leading to inaccurate safety conclusions.
- Nested case-control designs are considered an alternative but can introduce biases like confounding by indication.
- The presented alternative designs offer potential improvements for capturing real-world drug use in safety studies.
Conclusions:
- The intention-to-treat (ITT) approach in cohort studies may be inadequate for accurately assessing drug safety due to limitations in reflecting real-world drug use.
- Alternative designs, such as counter-matched nested case-control and case-crossover, are valuable for prospective post-authorization safety studies.
- These alternative designs aim to improve the accuracy and reproducibility of safety findings in pharmacovigilance.
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