In reply: To a carpenter, everything looks like a nail, and to a stroke thrombolysis sceptic, every study seems to confirm their opinion. A result cannot be “clinically important” yet statistically not so. We found no difference in symptomatic intracranial haemorrhage rates between our study and others using the same definition. The most widely accepted estimates of the true number needed to harm (for functional outcome at 3 months, following treatment within 3 hours) is about 30, as opposed to a number needed to benefit of around three.1
The full article is accessible to AMA members and paid subscribers. Login to read more or purchase a subscription now.
Please note: institutional and Research4Life access to the MJA is now provided through Wiley Online Library.
- 1 Royal Adelaide Hospital, Adelaide, SA.
- 2 Queen Elizabeth Hospital, Adelaide, SA.
- 3 Comprehensive Stroke Centre, Flinders Medical Centre, Adelaide, SA.
- 1. Saver JL. Number needed to treat estimates incorporating effects over the entire range of clinical outcomes: novel derivation method and application to thrombolytic therapy for acute stroke. Arch Neurol 2004; 61: 1066-1070.<eMJA full text>
- 2. Mishra NK, Ahmed N, Andersen G, et al. Thrombolysis in very elderly people: controlled comparison of SITS International Stroke Thrombolysis Registry and Virtual International Stroke Trials Archive. BMJ 2010; 341: c6046.
- 3. Lees KR, Bluhmki E, von Kummer R, et al. Time to treatment with intravenous alteplase and outcome in stroke: an updated pooled analysis of ECASS, ATLANTIS, NINDS, and EPITHET trials. Lancet 2010; 375: 1695-1703.
- 4. Wardlaw JM, Murray V, Berge E, Del Zoppo GJ. Thrombolysis for acute ischaemic stroke. Cochrane Database Syst Rev 2009; (4): CD000213.