A5V4d

Feverish illness in children
these studies of children with FWS. The levels of specificity and sensitivity from the most recent study
are used as baseline parameters for the model.
Table 11.7 Source of effectiveness data from the existing published studies
254
CRP PCT Source
Sensitivity 0.79 0.93 Galetto-Lacour et al. (2003) 178
Specificity 0.79 0.74
Sensitivity 0.89 0.93 Lacour et al. (2001) 245
Specificity 0.75 0.78
CRP C-reactive protein, PCT procalcitonin
Prevalence of SBI for children with fever without localising signs is a key parameter of the model.
However, no accurate prevalence data for the UK could be identified. Therefore, an estimate of 5%
was used in the first instance based on GDG expert opinion, which is a strong assumption of the
analysis. Table 11.8 summarises all the clinical data used as baseline parameters in the model.
Table 11.8 Baseline parameters for the effectiveness data
CRP PCT Source
Prevalence 0.05 0.05 GDG expert opinion
Sensitivity 0.79 0.93 Galetto-Lacour et al. (2003) 178
Specificity 0.79 0.74
CRP C-reactive protein, PCT procalcitonin
Costs
The perspective adopted by the economic analysis was that of the NHS, and prices are for 2006. The
cost of the test included the cost per investigation only. It was assumed that the price of the
investigation reflects the cost of reagents and the cost of labour as well. The cost of CRP could be
identified by the GDG members from their local services. However, the cost of PCT was more difficult
to estimate since a published price, including all associated costs, could not be identified from the
sources available. One GDG member provided the price for a PCT assay. Table 11.9 shows the cost
of each type of investigation and the source of the cost data. The potential cost of SBI treatment is not
included in the analysis.
Table 11.9 Baseline parameters for the cost data
CRP PCT Source
Cost per investigation £1.50 £9.00 GDG
CRP C-reactive protein, PCT procalcitonin
Results
A cohort of 1000 febrile children without localising signs for each type of investigation was assumed.
The results of the economic analysis are presented as cost per correct diagnosis. Using baseline
data, CRP appears to be a significantly less costly and possibly more accurate diagnostic test than
PCT in terms of correctly diagnosed cases (Table 11.10). Taking into account only the levels of
sensitivity, PCT is a better diagnostic test than CRP as it manages to capture more SBI (more true
positives). However, PCT may have a lower level of specificity than CRP which means that PCT
identifies fewer true negative results than CRP. Also, the decrease in the correctly diagnosed cases
having no SBI is higher than the increase in the correctly diagnosed cases having SBI and for this
reason the final number of correctly diagnosed cases is lower for PCT than CRP.