OnCo
termsTerm

Blinding (double-blind, open-label, placebo-controlled)

aka double-blind, double blind, double-blinded, blinded, open-label, open label, unblinded, placebo-controlled, placebo-controlled trial, matching placebo, single-blind, investigator-blinded, assessor-blinded, blinded assessment, blinded independent review, unblinding

Whether patients and doctors know which treatment is being given. Double-blind: neither knows (a placebo hides it). Open-label: both do, unavoidable for surgery or radiotherapy but a source of bias when judging progression and symptoms.

Blinding protects subjective outcomes (progression on scans, symptom scores, decisions to stop or switch) from expectation bias. Many oncology trials are open-label because the comparators differ in route or schedule; they compensate with blinded independent central review of imaging and hard endpoints such as overall survival. Placebo-controlled designs are standard for maintenance and adjuvant trials (adding a pill or nothing). Unblinding at interim analysis, or effective unblinding through side effects (alopecia, rash), can compromise a trial, and open-label designs tend to show larger investigator-assessed PFS effects than blinded review.

Category
Trials & regulation

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