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OS Data Maturity — SCE Medical Oncology MCQ

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HardClinical Trials & StatisticsOS Data MaturitySCE Medical Oncology

A group-sequential oncology trial planned its final overall-survival analysis after 500 deaths. At the data cut-off, 200 deaths have occurred and the report calls OS “40% mature”. What does that statement mean?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Forty percent of the target OS events have occurred, so this remains a relatively imprecise interim estimate

Explanation lettering: D = shown as A · E = shown as C · A = shown as D · C = shown as E

A is correct. Event-driven maturity is the observed proportion of the prespecified event target: 200 divided by 500 is 40%. It is not necessarily the proportion of participants who have died, elapsed calendar time or accumulated person-time. B ignores the protocol denominator. C confuses follow-up duration with event information and makes an invalid claim about censoring. D neither defines maturity nor proves proportional hazards. E counts analyses rather than deaths and ignores increasing precision. Statistical conclusions must follow the prespecified interim boundaries and multiplicity plan; there is no universal percentage at which every OS result becomes definitive.

Reference: EMA ICH E9 statistical principles for clinical trials: https://www.ema.europa.eu/en/ich-e9-statistical-principles-clinical-trials-scientific-guideline