Apixaban for the prevention of venous thromboembolism in people ...

5.2.10 Sensitivity analyses
Methods
One way sensitivity analyses were performed for a number of parameters (Table 5.18).
Table 5.18 Input for one-way sensitivity analyses (adapted from Table 80, MS-page 168)
Variable Base case One-way sensitivity analysis
Discount rate 3.5% 0% and 6%
Health care unit costs Listed in MS-Table 80 +/-10% & PBR tariff costs 67
Duration of short-term
utility decrement
Listed in MS-Table 80 +/-10%
Utility treated VTE -0.01 = -0.095
Weighted mean of
LMWH costs
£4.04 £3.76 (weighted mean) / £2.82 (lowest)
Dabigatran cost £4.20 -50%
Wastage
apixaban
cost
12 days for TKR / 34 for THR
15 days of apixaban for TKR / 45 for
THR
Treatment duration Apixaban TKR 12 / THR 34, Reduce TKR to 10 days and THR to 28
Enoxaparin TKR 12 / THR 34, days for all except dabigatran /
Rivaroxaban TKR 12 / THR 33, increased TKR to 14 days and THR to
Dabigatran TKR 8 / THR 32
38 days for apixaban.
Time horizon 35 years 1, 5, 10, 20 years
Age at surgery THR males 65.89, females
68.51; TKR males 68.26,
females 68.14
40, 50, 80
Length of stay of
index hospitalisation
5 days +/- 10%, +/- 20%
Total VTE and allcause
death apixaban Listed in MS-Table 80 Upper 95% confidence interval / +10%
Total VTE and allcause
death
comparator
Listed in MS-Table 80 Upper 95% confidence interval / +10%
Bleeding events
apixaban Listed in MS-Table 80 Upper 95% confidence interval / +10%
Bleeding events
comparator Listed in MS-Table 80 Upper 95% confidence interval/ +10%
In addition, scenario analyses were undertaken. In these scenario analyses, the sources of data
were changed. First, in the indirect comparison the data on 30mg enoxaparin were included
(‘indirect comparison group 2’). Second, a mixed treatment comparison was used, both for the
base case group excluding 30mg enoxaparin (‘MTC group 1’) and while including 30mg
enoxaparin (‘MTC group 2’). The scenario analysis using the Group 2- indirect comparison
was performed for TKR only.
Finally, probabilistic sensitivity analyses (PSA) were undertaken. The MS stated that the PSA
included only parameters that were not varied in the one-way sensitivity analyses. Normal
distributions were used for treatment duration. Lognormal distributions were used for relative
risks. Beta distributions were used for long term probabilities and utility scores. Gamma
distributions were used for costs and utility decrements.
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