Financial impact of a novel pre-eclampsia diagnostic test versus standard practice: a decision-analytic modeling analysis from a UK healthcare payer perspective

Figures & data

Figure 1.  Clinical overview of the budget impact model. *Per pre-eclampsia community guidelines, PE cannot be diagnosed before week 20³. PE, pre-eclampsia.

Figure 2.  Distribution of the patient population in the model: standard practice vs. novel pre-eclampsia test. PE, pre-eclampsia.

Table 1.  Summary of clinical model inputs.

Model parameter	Default value	Data sources
Inputs for standard practice and novel pre-eclampsia test scenarios
Cohort size (i.e., number of pregnant women)	1,000	Assumption
Patients with risk factors indicative of pre-eclampsia in the UK	15%	UK interviews
Overall pre-eclampsia incidence in the UK	4.03%	Bhattacharya et al., 20054
Proportions
Mild pre-eclampsia	93.6%	Bhattacharya et al., 20054
Severe pre-eclampsia	4.75%	Bhattacharya et al., 20054
Eclampsia	1.65%	Bhattacharya et al., 20054
Maternal death due to pre-eclampsia complications	0%	Bhattacharya et al., 20054
Incidence of pre-eclampsia among patients with risk factors	0.60%	Calculated as product of percentage of patients with risk factors in the UK and overall incidence of pre-eclampsia in the UK (i.e., 15% × 4.03% = 0.60%)
Incidence of pre-eclampsia among patients without risk factors	3.43%	Calculated as product of percentage of patients without risk factors in the UK and overall incidence of pre-eclampsia in the UK (i.e., 85% × 4.03% = 3.43%)
Inputs specific to each of the scenarios
Pre-eclampsia test sensitivity and specificity
For standard practice scenario
Sensitivity in patients with risk factors	46%	Meads et al., 200814; pooled average of various sensitivity and specificity estimates of current pre-eclampsia tests
Specificity in patients with risk factors	83%
Sensitivity in patients without risk factors	46%
Specificity in patients without risk factors	83%
For novel pre-eclampsia test scenario
Sensitivity in patients with risk factors	82%	Verlohren et al., 201013
Specificity in patients with risk factors	95%
Sensitivity in patients without risk factors	82%
Specificity in patients without risk factors	95%
Proportional distribution of pre-eclampsia patient population according to diagnostic success
Standard practice scenario
TP in patients with risk factors		Calculated according to test-specific sensitivity and specificity values reported above
FP in patients with risk factors	0.28%
FN in patients with risk factors	2.45%
TN in patients with risk factors	0.33%
TP in patients without risk factors	11.95%
FP in patients without risk factors	1.58%
FN in patients without risk factors	13.87%
TN in patients without risk factors	1.85%
Novel pre-eclampsia test scenario	67.71%
TP in patients with risk factors	0.50%	Calculated according to test-specific sensitivity and specificity values reported above
FP in patients with risk factors	0.72%
FN in patients with risk factors	0.11%
TN in patients with risk factors	13.68%
TP in patients without risk factors	2.81%
FP in patients without risk factors	4.08%
FN in patients without risk factors	0.62%
TN in patients without risk factors	77.50%

TP, true positive; FP, false positive; FN, false negative; TN, true negative.

Table 2.  Summary of economic inputs.

Model parameter	Default value	Data sources
Inputs for standard practice and novel pre-eclampsia test scenarios
PE assessment costs between booking and week 20		National Health Service tariffs, 2008–200916; Mulhaven Medical Laboratory, 200917; Meads et al., 200814; UK interviews
Patients with pre-eclampsia risk factors	£2,265.80
Patients without pre-eclampsia risk factors	£615.25
Drug costs (between weeks 20 and 40 of gestation)		British National Formulary, 200915; UK interviews
Mild pre-eclampsia	£28.25
Severe pre-eclampsia	£127.30
Eclampsia	£163.19
Maternal death due to pre-eclampsia complications	£0
Additional aspirin therapy cost for patients with pre-eclampsia risk factors	£2.74
Pre-eclampsia management costs, by diagnostic success (between weeks 20 and 40 of gestation)
TP with mild pre-eclampsia	£9,576.25	National Health Service tariffs, 2008--200916; Mulhaven Medical Laboratory, 200917; Meads et al., 200814; Murphy et al., 200018; UK interviews
TP with severe pre-eclampsia	£14,545.49
TP with eclampsia	£21,340.12
TP with maternal death due to pre-eclampsia complications	£0
FP with pre-eclampsia risk factors	£9,576.25
FN with mild pre-eclampsia	£4,480.38
FN with severe pre-eclampsia	£11,308.87
FN with eclampsia	£17,122.77
FN with maternal death due to pre-eclampsia complications	£0
TN with pre-eclampsia risk factors	£0
Inputs specific to novel pre-eclampsia test scenario
Cost of novel pre-eclampsia test
Per test (for patients with initial positive test result)	£31.13	Roche Diagnostics Ltd, data on file, 2009; 52 CHF converted to UK pounds; exchange rate = 0.59849 as of 14 May 2009
All testing (for patients with initial negative test result)	£93.39	Lapaire et al., 201019, Levine et al., 200420; test repeated every 6 weeks on pregnant patients with negative result (i.e., £31.13 × 3 = £93.39)

TP, true positive; FP, false positive; FN, false negative; TN, true negative

Figure 3.  Shift in patient population by pre-eclampsia diagnosis. PE, pre-eclampsia.

Table 3.  Comparison of total costs in the two scenarios – standard practice and novel pre-eclampsia test.

Cost source	Standard practice	Novel pre- eclampsia test	Budget impact*		Comment
			Cohort (1,000)	Per-patient†
True positive	£202,154	£361,389	£159,236	£159	Cost increase due to a greater number of correct diagnoses, and a greater number of pre-eclampsia patients properly treated
True negative	£687,617	£872,177	£184,560	£185	Cost increase due to a greater number of correct diagnoses
False positive	£1,707,802	£503,789	−£1,204,014	−£1,204	Cost reduction from avoiding treating ‘pre-eclampsia patients’ unnecessarily
False negative	£128,652	£43,561	−£85,090	−£85	Reduction in cost due to timely management of pre-eclampsia
Total	£2,726,224	£1,780,916	−£945,309	−£945	Total and net budget impact and cost savings

*Negative values represent cost savings.

†Per pregnant woman, regardless of pre-eclampsia status.

Figure 4.  Budget impact of novel pre-eclampsia test in three screening scenarios: a comparison. PE, pre-eclampsia.

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