Published: 12/12/2001, Volume II2, No. 5835 Page 23

We read with interest your article, 'Link response time to survival says 'maverick'', (news, page 6, 28 November) as the authors of the cited South East ambulance clinical audit group study.

Contrary to the assertion made by Staffordshire Ambulance Service trust chief executive Roger Thayne, and reported in HSJ, our study did not conclude that '6,000 lives would be saved if trusts across England matched the performance of Staffordshire Ambulance Service trust'.

Mr Thayne has been so focused on making his point about linking ambulance response times and health outcomes that he has failed to draw proper conclusions from our audit.

SEACAG was established to promote evidence-based practice and has already demonstrated this ethos in previous collaborative audits. While SEACAG agrees with Mr Thayne's contention that performance in ambulance services should be linked to health outcomes, we fundamentally disagree with the comparisons being made between our cardiac arrest audit data and the cardiac arrest data from his trust for these reasons:

nIt is invalid to draw conclusions from two different audits conducted at different times, with different inclusion criteria. The study populations also differ.

nSEACAG reports strictly against the internationally recognised methodology of the 'Utstein style'. Staffordshire has never been transparent about its methodology.

nSEACAG reports survival as discharge from hospital while Staffordshire reports survival as return of spontaneous circulation. This is a measure widely condemned as an nMr Thayne links his conclusions to the recently implemented ambulance service response times. The SEACAG audit was conducted in advance of these being introduced and it is therefore not appropriate to make such comparisons.

Mr Thayne neglects to mention that work is already underway, led by the joint royal colleges ambulance liaison committee and the Ambulance Service Association, on the development of a consensus data set and definitions for cardiac arrests. All trusts will then be in a position to audit like data with like, with confidence that any conclusions drawn will be robust enough to produce a national cardiac arrest outcome audit.

Lucy Evans South East ambulance clinical audit group