Aanesthetic Agents for Day Surgery - NIHR Health Technology ...

Background
Semi-fixed costs account for resource use that
remains unchanged over a range of output,
but given sufficient changes in activity the costs
increase or decrease. Staff costs are the principal
component of semi-fixed costs for healthcare
interventions. There was no available information
on the resource use associated with the staff
involved during the day procedure, but the type
of surgical intervention and NHS trust study site
was assumed to have an impact on the number
and skill mix of the staff involved. There was no
evidence to suggest that there would be differences
in semi-fixed costs between the surgical groups or
study sites included in the main study. A substudy
was required to provide information on dayprocedure
staff deployment and skill mix to
calculate the associated resource use and semifixed
costs for each surgical group and study site.
This substudy is referred to hereafter as the staff
resource use study.
The aim of the staff resource use study was to
provide information on staff deployment and
skill mix during the day-surgery episode for each
surgical group and study site included in the
main study.
The objectives of the staff resource use study
were to:
• confirm the stages and tasks that comprise a
day-surgery episode
• identify the type and grade of NHS staff present
at each stage of the day-surgery episode
• quantify the length of time each grade of
NHS staff takes to complete each task during
the stages of a day-surgery episode for the
surgical groups and study sites included in
the main study.
Method
Structured face-to-face interviews with NHS staff
were used to confirm the tasks that a day-surgery
episode comprises. Direct non-participant
observation was selected as the preferred method
to determine staff resource use. Subjective
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Appendix 19
Calculating semi-fixed costs
Health Technology Assessment 2002; Vol. 6: No. 30
evaluation, self-reporting and collecting
productivity data were alternative methods, but
these do not have the advantage of being able
to carefully describe and record the work of the
person under observation 248 and may be subject
to the potential bias of subjective, inexact or
inaccurate recording. 249 Non-participant observation
was used to collect data on staff resource
use in the anaesthetic room and operating theatre.
It was costly and impractical to observe directly
the entire day-surgery episode and face-to-face
interviews were used to collect NHS staff members’
subjective estimates of resource use associated
with the process of admitting and discharging,
transferring between the theatre and the ward
and monitoring postoperatively in recovery
and on the ward.
The perspective of the staff resource use study
was consistent with that of the empirical study
and included costs accruing to the NHS staff
resources. The staff resource use study started
when the patient arrived at the hospital ward for
their planned admission and ended when the
patient was discharged from the care of the
relevant NHS trust and left the hospital ward.
Staff resource use at the preoperative clinic
was excluded.
The type of NHS staff (e.g. surgeon, nurse),
grade of NHS staff (e.g. consultant, grade E)
and time spent working in the anaesthetic room
and operating theatre were noted for each patient
included in the staff resource use study sample.
The unit costs (average salary per minute, including
employer’s contributions) for the relevant
type and grade of NHS staff (see appendix 20)
were then multiplied by their working time to
calculate the total semi-fixed cost for each patient.
The time spent in the anaesthetic room and
operating theatre was recorded as part of the
main study.
Study population
The target study population was composed of
those patients who had been admitted to a ward,
or unit, for day surgery in the main study NHS
trust sites. The surgical groups matched those
in the main study:
223