Intended for healthcare professionals

Endgames Statistical Question

Survival (time to event) data: median survival times

BMJ 2011; 343 doi: (Published 10 August 2011) Cite this as: BMJ 2011;343:d4890
  1. Philip Sedgwick, senior lecturer in medical statistics1,
  2. Katherine Joekes, lecturer in clinical communication1
  1. 1Section of Medical and Healthcare Education, St George’s, University of London, Tooting, London, UK
  1. Correspondence to: P Sedgwick p.sedgwick{at}

A meta-analysis investigated the effects of palliative chemotherapy in patients with locally advanced or metastatic colorectal cancer. Randomised controlled trials that compared palliative chemotherapy with supportive care were included. Seven trials with a common study period of 24 months were identified, providing individual data on a total of 866 patients. Outcome measures included the length of time until death after starting treatment. The Kaplan-Meier survival curves for the length of time until death for the treatments of palliative chemotherapy and supportive care were presented (figure). The median survival time was estimated to be 8.0 months in the supportive care group and 11.7 months in the chemotherapy group.1

Kaplan­Meier survival curves of overall survival for the chemotherapy and supportive care treatment groups. The number of events (total deaths in each group) are indicated. The median survival time for each treatment group is the length of time corresponding to the probability of 0.51 …

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