Volume 194 - Issue 8
A population-based study of thrombolysis for acute stroke in South Australia
Authors: Tim Kleinig, James M Leyden, Andrew Lee and Jim Jannes
Med J Aust 2011; 194 (8): 431-432. || doi: 10.5694/j.1326-5377.2011.tb03050.x
Published online: 18 April 2011
Published online: 18 April 2011
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
Our study does not suggest that thrombolysis increases mortality. Mortality cannot be compared between different populations, with different aetiology and severity.
We have demonstrated a large number of relative “protocol violations” according to 2007 guidelines, the most common of which was that the patient was older than 80 years, but there is robust evidence that thrombolysis is safe and effective in this cohort.2
The benefit of a therapy cannot be assessed by a tally of “positive” and “negative” trials. A recent meta-analysis of all tissue plasminogen activator trials (seven trials, 2199 patients),3 and the relevant Cochrane review,4 confirm benefit in appropriate patients treated with tissue plasminogen activator within 4.5 hours. Stroke thrombolysis is effective. We must overcome the barriers to administering it frequently, safely and rapidly.
References
- 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>
- 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. 0_pgfId-2315998
- 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. 0_pgfId-2316006
- Wardlaw JM, Murray V, Berge E, Del Zoppo GJ. Thrombolysis for acute ischaemic stroke. Cochrane Database Syst Rev 2009; (4): CD000213. 0_CBBJGCJJ