Further research is needed involving a larger sample of Trusts and Schools of Nursing to replicate the results of this study and to compare methods of the assessment of performance in terms of competency in practice on qualification.
A number of limitations are also acknowledged: these include under-representation in the sample of Trusts from the Midlands region and AMHS.
Even if a larger sample of trusts and cases was taken, it would be unlikely to reveal a clinically important association, even if it achieved statistical significance.
As such, they knew that the sample of trusts had been stratified according to HSMR and could easily have found out the HSMRs for the trusts they were studying.
We determined that, based on an avoidable death proportion of 5% (SD 2%), 6 a sample of 34 trusts and 100 cases per trust would have 80% power to detect a regression coefficient of 1.4 (that is, a 1.4 percentage point increase in avoidable death proportion for a 10 point increase in SMR).
19 Thirty-one NHS trusts representing 46 hospitals were selected for participation from a random sample of NHS trusts in England stratified by geographic area, size and teaching status.
However, a recent NHS Liaison report on agency staff found in their sample of 46 trusts, about 140 agencies were used (half of which were for medical staff).
We feel it is reasonable to conclude that, in the sample of NHS trusts examined, the NICE guideline had only a small effect on clinical practice.
The main limitation of the present study is that, although in-depth qualitative data was collected, this was necessarily dependent on the views of selected senior staff in a relatively small sample of hospital trusts.
Questionnaire-based survey of all English NHS acute and mental health hospital settings, supplemented by semi-structured telephone interviews with 22 respondents and direct observation at a sample of 15 Trusts (22 different sites).
