ITT preserves randomization and is the primary analysis for superiority trials. Per-Protocol analyses are typically supportive - and primary in non-inferiority trials, where ITT can bias toward 'no difference'. ITT analyzes all randomized subjects in their assigned group, whatever happened next, while per-protocol excludes subjects with major protocol deviations. Modified ITT variants, such as subjects who received the device, are common in device trials and must be defined in advance. The ICH E9(R1) estimand framework now encourages sponsors to state exactly which treatment effect they are estimating.

Why it matters

Non-inferiority device trials require pre-specified analysis populations and consistent ITT/PP results; mismatch is a frequent reason for FDA panel debate.

Common pitfalls

•Misinterpreting an ITT analysis that shows no significant difference as a definitive lack of treatment effect, when a PP analysis might reveal otherwise.
•Failing to pre-specify the analysis populations for both ITT and PP analyses in the clinical trial protocol.
•Not adequately addressing discrepancies between ITT and PP results in regulatory submissions, leading to questions or objections from regulatory bodies.
•Applying ITT analysis as the primary endpoint in a non-inferiority trial without careful consideration of its potential to bias the results toward equivalence.
•Excluding participants from the ITT analysis who dropped out or did not adhere to the protocol, thereby compromising the integrity of randomization.

Sources

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Why compare MedTech terms side by side?

MedTech terminology is full of pairs that look interchangeable but carry very different regulatory, clinical, and commercial consequences. Picking the wrong framework, pathway, or standard early in a project can add months to a submission, invalidate clinical evidence, or trigger an audit finding. Side-by-side comparison is the fastest way to surface those differences before they become costly mistakes.

Each comparison on this page pulls from the same vendor-neutral, sourced definitions used throughout the MedTech Terms glossary. You see the one-line summary, the formal definition, why it matters in practice, common pitfalls, and the primary sources (FDA guidance, EU MDR/IVDR articles, ISO/IEC standards, MDCG documents, IMDRF principles) that back each entry. That makes the comparison defensible in regulatory strategy memos, design reviews, and submission narratives.

Common comparison patterns

Regulatory pathway choice - 510(k) vs PMA, 510(k) vs De Novo, Abbreviated vs Special 510(k).
Quality systems - QSR vs ISO 13485, QMSR vs QSR.
Software classification - SaMD vs SiMD, Locked vs adaptive AI.
EU frameworks - MDR vs IVDR, CE Mark vs UKCA.
Cybersecurity artifacts - SPDX vs CycloneDX SBOM, CVE vs CVSS.
Post-market actions - Recall vs field action, Removal vs correction.

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MedTech Terms is a vendor-neutral community resource sponsored by Blue Goat Cyber. Definitions are written for educational use and are not legal or regulatory advice.