--- title: "Blinding and Masking, Definition | MedTech Terms" description: "Procedures that hide treatment assignment from patients, investigators, or assessors to reduce bias. Plain-English Clinical & Trials definition for MedTech team" lang: en json-ld: | { "@context": "https://schema.org", "@graph": [ { "@type": "DefinedTerm", "@id": "https://medtechterms.com/terms/blinding#term", "name": "Blinding and Masking", "description": "Single-, double-, and triple-blinding apply progressively to patients, investigators, and outcome assessors. 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[Home](/) 2. / 3. [Terms](/terms) 4. / 5. [Clinical & Trials](/terms?cat=Clinical%20%26%20Trials) 6. / 7. Blinding and Masking [All terms](/terms) Clinical & Trials [Clinical Evidence](/ecosystems/clinical-evidence) # Blinding and Masking Procedures that hide treatment assignment from patients, investigators, or assessors to reduce bias. Reviewed by [Christian Espinosa, Founder, Blue Goat Cyber](/authors/christian-espinosa) Last reviewed May 5, 2026 ## Definition Single-, double-, and triple-blinding apply progressively to patients, investigators, and outcome assessors. Device trials often achieve only assessor-blinding due to the visible nature of devices/procedures. What the regulation says Blinding and masking are critical study design elements emphasized by regulatory bodies like the FDA in their guidance on clinical trials for medical devices, particularly to minimize bias. The EU [MDR](/terms/mdr-reporting), in Annex I, Section 21.2, also stresses the importance of appropriate statistical methods and study design to ensure the scientific validity and reliability of clinical data. These practices aim to ensure objectivity in assessing treatment effects and patient outcomes. ## What this means in practice Independent core labs and blinded adjudication committees are standard mitigations for device trials where full blinding is impossible. ## Examples - A clinical trial for a novel implantable glucose monitor might blind the patients to whether they received the active device or a similar-looking placebo device that does not provide glucose readings. - In a study evaluating a surgical robot, the surgeons and patients may not be blind, but the outcome assessors evaluating post-operative complications and recovery time can be blinded to the treatment arm. - A study comparing two different drug-eluting stents might anonymize the stent type in patient records and blind the radiologists interpreting follow-up angiograms to stent assignment. Common pitfalls - • Failure to document the rationale for the chosen blinding level can lead to regulatory scrutiny. - • Inadequate blinding procedures can compromise the scientific validity of clinical trial results, leading to questions from regulatory authorities. - • Assuming that device trials cannot be blinded at all, rather than seeking opportunities for partial blinding, is a common pitfall. - • Not accounting for potential unblinding events and having a plan to address them can undermine study integrity. ## Frequently asked questions Why is blinding often challenging in MedTech clinical trials? Blinding is challenging due to the visible nature of devices, the need for clinician interaction during procedures, and the distinct characteristics of device interventions compared to pharmaceutical products. What is the primary goal of blinding in clinical trials? Are there different levels of blinding? How can blinding be maintained when a device is clearly visible? ## Related terms Grouped by theme ### Editor's picks · Hand-selected related concepts [ Clinical & Trials Sham Control Placebo-equivalent for device trials - a non-therapeutic procedure that mimics the investigational intervention. ](/terms/sham-control) ### More in Clinical & Trials · Same category [ Clinical & Trials Adaptive Trial Design Trial design that pre-specifies opportunities to modify aspects (sample size, arms, endpoints) based on interim data. ](/terms/adaptive-trial)[ Clinical & Trials Adverse Event(AE) Any untoward medical occurrence in a subject, whether or not related to the device. ](/terms/adverse-event)[ Clinical & Trials ALCOA+ Data integrity principles: Attributable, Legible, Contemporaneous, Original, Accurate (plus Complete, Consistent, Enduring, Available). ](/terms/alcoa-plus)[ Clinical & Trials Analytical Sensitivity An IVD's ability to detect small quantities of an analyte. ](/terms/analytical-sensitivity) Cited by Where this term appears across MedTech Terms. Ecosystems (1) - [Clinical Evidence](/ecosystems/clinical-evidence) ## Primary references 3 sources Link health: 3 verified · last checked 2026-06-20 ICH· 2 ISO· 1 1. [1 ICH E9 Verified ICH · ich.org ](https://www.ich.org/) 2. [2 ICH Guidelines Verified ICH · ich.org ](https://www.ich.org/page/ich-guidelines) 3. [3 ISO 14155 Standard Page Verified ISO · iso.org ](https://www.iso.org/standard/71690.html) Inline markers like \[1\] jump to the matching reference above. Sponsor note ### Clinical evidence intersecting with device security? We support clinical-stage MedTech teams whose investigational devices touch patient data or hospital networks. [Book a 30-minute discovery session](https://go.bluegoatcyber.com/meetings/blue-goat-cyber/discovery-session) - No obligation - Expert-led from minute one - NDA available on request MedTech Terms is a community resource sponsored by [Blue Goat Cyber](https://bluegoatcyber.com). Definitions are independent of any vendor. On this term Category Clinical & Trials Sources 3 Updated 5/5/2026 [Compare with another term](/compare?a=blinding) Learn in 60 seconds Card Lesson Quiz Procedures that hide treatment assignment from patients, investigators, or assessors to reduce bias. - · Independent core labs and blinded adjudication committees are standard mitigations for device trials where full blinding is impossible. - · Device trials often achieve only assessor-blinding due to the visible nature of devices/procedures. Remember this Watch out: Failure to document the rationale for the chosen blinding level can lead to regulatory scrutiny. Related terms - [Sham Control ](/terms/sham-control) You may also need Auto-suggested from Clinical & Trials and shared keywords. - [Intent-to-Treat vs Per-Protocol(ITT / PP) ](/terms/itt-pp) - [Sample Size and Statistical Power ](/terms/sample-size-power) - [Bayesian Trial Design ](/terms/bayesian-trial) - [Pragmatic Trial ](/terms/pragmatic-trial) - [Propensity Score Methods ](/terms/propensity-score) - [Real-World Data(RWD) ](/terms/rwd) [All Clinical & Trials terms](/terms?cat=Clinical%20%26%20Trials) From the Blue Goat network Related resources and services on this topic. - [ MedTech Launchpad MedTech funding rounds, accelerators, and launch resources. ](https://medtechlaunchguide.com) MedTech Terms An authoritative, plain-language reference for the regulatory, quality, cybersecurity, and software terms that shape modern medical devices. 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