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Auguste P, Barton P, Hyde C, et al. An Economic Evaluation of Positron Emission Tomography (PET) and Positron Emission Tomography/Computed Tomography (PET/CT) for the Diagnosis of Breast Cancer Recurrence. Southampton (UK): NIHR Journals Library; 2011 Apr. (Health Technology Assessment, No. 15.18.)

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An Economic Evaluation of Positron Emission Tomography (PET) and Positron Emission Tomography/Computed Tomography (PET/CT) for the Diagnosis of Breast Cancer Recurrence.

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Appendix 2Model-based assumptions

Appendix 2.1. Assumptions from NICE (2009) guidelines

Here we present the assumptions regarding the study population, treatment and survival used by NICE in its economic evaluation. The most cost-effective strategy was used as the basis of the treatment cost presented in Table 2.

TABLE 7Model assumptions used in the NICE 2009 report24

Assumptions
Study population

Women with metastatic breast cancer who had previously been treated with anthracycline (treatment may have been used as adjuvant treatment)
Patients in whom the disease is hormone responsive will receive alternative/additional treatment
Treatment

Patients will receive first-line therapy; there is the possibility of the patient dying from a toxic death. The assumption is that a toxic death can only occur after first-line therapy
There is a time lag of one month between discontinuing first-line therapy and commencing second-line therapy. In the absence of toxicity the patient will continue first-line therapy. At this point it is assumed that response can be assessed, to the patient faces a probability of responding to therapy, or having stable disease or not
Capecitabine used as first-line treatment or part of a combination of first-line treatment will not be used in second-line treatment
The ‘no chemotherapy’ treatment would result in no progression-free survival and 5 months' survival with progressive disease
Survival

Overall survival was assumed to be time to progression of first-line treatment, time to progression of second-line treatment, time to progression of third-line treatment and progression to death (5 months)
Survival and time to progression followed exponential distributions
Authors assumed the utility with progressive disease, 0.45
Utility associated with stable disease, 0.65
Utility associated with progressive disease, 0.45
Cost estimation

For treatment which required a combination of two drugs, it was assumed that there will be one administration cost
At the beginning of each cycle, it was assumed that the patient will have an oncologist consultation

We used strategy 14, the most cost-effective strategy, which leads to an expected mean cost of £18,118, which we inflated to 2008 prices.

Appendix 2.2. Accuracy data for conventional work-up, positron emission tomography and positron emission tomography/computed tomography

TABLE 8Patient data: direct and indirect comparisons of the sensitivity and specificity of PET compared with CITs

ComparisonPET sensitivity, % (95% CI)CIT sensitivity, % (95% CI)Relative sensitivity (95% CI)PET specificity, % (95% CI)CIT specificity, % (95% CI)Relative specificity (95% CI)
Direct PET vs CIT89 (83 to 93), n = 1079 (72 to 85), n = 101.12 (1.04 to 1.21), p = 0.00593 (83 to 97)83 (67 to 92)1.12 (1.01 to 1.24), p = 0.036
Indirect PET vs CIT91 (87 to 93), n = 2581 (73 to 87), n = 111.12 (1.04 to 1.21), p = 0.00586 (79 to 91)73 (59 to 83)1.18 (1.03 to 1.36), p = 0.017

Reproduced from Pennant et al.17

TABLE 9Patient data: direct comparison of the sensitivity and specificity of PET/CT compared with CT and indirect comparison of PET/CT compared with a range of CITs

ComparisonPET/CTsensitivity, % (95% CI)CIT sensitivity, % (95% CI)Relative sensitivity (95% CI)PET/CTspecificity, % (95% CI)CIT specificity, % (95% CI)Relative specificity (95% CI)
Direct PET/CT vs CT95 (88 to 98), n = 480 (65 to 90), n = 41.19 (1.03 to 1.37), p = 0.01589 (69 to 97)77 (50 to 92)1.15 (0.95 to 1.41), p = 0.157
Indirect PET/CT vs CIT95 (89 to 97), n = 578 (72 to 84), n = 111.21 (1.11 to 1.31), p < 0.000189 (76 to 96)79 (65 to 88)1.13 (0.99 to 1.29), p = 0.063

Reproduced from Pennant et al.17

Appendix 2.3. Beta and normal distributions for accuracy, prevalence, treatment and expected quality-adjusted life-years

Beta distributions

TABLE 10Probability distribution of the sensitivities by strategy

StrategyBase-case sensitivitiesRange (95% CI)Probability distributionSource
Conventional work-up0.800.72 to 0.87Beta (85.6, 21.4)Derived from data presented in Pennant et al.17
PET0.910.87 to 0.93Beta (282.1, 27.9)Derived from data presented in Pennant et al.17
PET/CT0.950.89 to 0.97Beta (71.25, 3.75)Derived from data presented in Pennant et al.17
PET together with conventional work-up0.990.97 to 1.00Beta (168.3, 1.7)Derived from data presented in Pennant et al.17

TABLE 11Probability distribution of the specificities by strategy

StrategyBase-case specificitiesRange (95% CI)Probability distributionSource
Conventional work-up0.760.59 to 0.88Beta (20.52,6.48)Derived from data presented in Pennant et al.17
PET0.860.79 to 0.91Beta (103.2, 16.8)Derived from data presented in Pennant et al.17
PET/CT0.890.76 to 0.96Beta (27.145, 3.355)Derived from data presented in Pennant et al.17
PET together with conventional work-up0.680.45 to 0.89Beta (12.24, 5.76)Derived from data presented in Pennant et al.17

TABLE 12Probability distribution of the prevalence

Base-case prevalenceRange (95% CI)Probability distributionSource
Prevalence0.690.66 to 0.72Beta (655.5, 294.5)Derived from data presented in Pennant et al.17

Normal distributions

TABLE 13Normal distribution for parameter (treatment)

Cost (£)Probability distributionStandard deviationSource
Treatment (docetaxel, capecitabine and no chemotherapy18, 643Normal1864.3aNICE23
a

Original treatment cost taken from Table A1.14 (strategy 14) NICE, 200923 (£18,118) cost year 2007. This figure was inflated to 2008 price by the use of the Hospital and Community Health Services combined pay and price inflation index.26

TABLE 14Normal distribution for parameter (QALYs expected for treatment)

QALYProbability distributionStandard deviationSource
Total QALYs expected for treatment0.8737Normal0.08737NICE24

Appendix 2.4. Detailed results of the sensitivity analysis

1(a) Increasing the sensitivity of PET/CT to 97% – all other parameters as base case (cost per QALY)

TABLE 15aIncreasing the sensitivity of PET/CT to 97% – all other parameters as base case (cost per QALY)

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£10,8624.7827
PET£12,805£19424.84900.0663£29,300
PET/CT£13,811£10064.88520.0362£27,800
PET/CT as an adjunct to conventional work-up£14,616£8054.89970.0145£55,600

1(b) Increasing the specificity of PET/CT to 100% – all other parameters as base case (cost per QALY)

TABLE 15bIncreasing the specificity of PET/CT to 100% – all other parameters as base case (cost per QALY)

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£10,8624.7827
PET£12,805£19424.84900.0663£29,300
PET/CT£13,547£7424.87320.0241£30,800
PET/CT as an adjunct to conventional work-up£14,561£10144.89730.0241£42,000

1(c) Reducing the cost of the PET/CT strategy from the base-case value of £1236 to £1210

TABLE 15cReducing the cost of the PET/CT strategy from the base-case value of £1236 to £1210

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£10,8624.7827
PET£12,805£19424.84900.0663£29,300
PET/CT£13,526£7214.87320.0241£29,900
PET/CT as an adjunct to conventional work-up£14,56410384.89730.0241£43,100

2(a) Reducing the prevalence to the lowest value in range (0.19)

TABLE 16aSensitivity analysis results for cost per QALY (2007–8 prices)

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£336811.3694
PET£4270£90211.38770.0183£49,400
PET/CT£4639£36911.39430.0066£55,600
PET/CT as an adjunct to conventional work-up£5291£65211.40100.0066£98,200

2(b) Increasing the prevalence to the highest value in the range (0.93)

TABLE 16bSensitivity analysis results for cost per QALY (2007–8) prices

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£14,4631.6211
PET£16,904£24421.71050.0894£27,300
PET/CT£17,833£9281.7430.0325£28,600
PET/CT as an adjunct to conventional work-up£19,018£11851.77550.0325£36,500

3. Using specificity from just one (conventional work-up) of the two combined tests for PET/CT as an adjunct to conventional work-up

TABLE 17Base-case results from the analysis cost per QALY (2007–8 prices)

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£10,8644.7827
PET£12,807£19424.84900.0663£29,300
PET/CT£13,554£7474.87320.0241£31,000
PET/CT together with conventional work-up£14,563£10094.89730.0241£42,000

4. Omitting PET alone as a strategy

TABLE 18Base-case results from the analysis cost per QALY (2007–8 prices)

StrategyMean cost per strategyDifference in costsEffectiveness (QALY)Incremental QALYsICER
Conventional work-up£10,8644.7827
PET/CT£13,554£26904.87320.0905£29,700
PET/CT together with conventional work-up£14,563£10094.89730.0241£41,900
© 2011, Crown Copyright.

Included under terms of UK Non-commercial Government License.

Bookshelf ID: NBK99353

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