Base-case model parameters
| Parameter | Point estimate | SE | Probabilistic distribution | Data source |
|---|---|---|---|---|
| Mean age (years) | 70 | NA | NA | 13 and 14 |
| Model lifetime (years) | 36 | NA | NA | 13 and 14 |
| Discount rate (costs and outcomes) | 0.035 | NA | NA | 17 |
| Proportion-confirmed metastases in progression | 0.4 | 0.08 | β | AA24 |
| Transition probabilities (monthly) | ||||
| Cryotherapy to ADT | Spline regression fitted to Kaplan Meier DFS curve | 13 | ||
| Spline model hazard intercept | −4.58 | 0.408 | Normal | Spline PH regression13 |
| Spline model hazard s0 | 1.01 | 0.096 | Normal | Spline PH regression13 |
| Spline model hazard s1 | 0.303 | 0.068 | Normal | Spline PH regression13 |
| Deferred ADT to ADT | 0.014 | 0.005 | β | 36 |
| ADT to progression | 0.016 | 0.004 | β | 36 |
| Relative risk ADT to progression post-SC | 1.5 | 1.38 | Log normal | AA |
| UK mortality rates: males, age specific | 2010 UK interim life tables | 40 | ||
| Prostate cancer mortality: age specific | 2010 UK prostate cancer mortality rates | 3 | ||
| Adverse event probabilities | ||||
| Fistula | 0.05 | 0.010 | β | 22 33 and 35 |
| Incontinence | 0.12 | 0.024 | β | 22 33 and 35 |
| Retention | 0.07 | 0.014 | β | 22 33 and 35 |
| Lower urinary tract symptoms | 0.14 | 0.028 | β | 22 33 and 35 |
| Perineal pain | 0.04 | 0.008 | β | 22 33 and 35 |
| Haematuria | 0.05 | 0.01 | β | 22 33 and 35 |
| Urethral stricture | 0.10 | 0.02 | β | 22 33 and 35 |
| Hot flushes | 0.10 | 0.02 | β | Clinical expertise32 |
| Cost | ||||
| Cryotherapy* | £8509 | NA | NA | 18 and 20 |
| First-line ADT per cycle* | £83 | NA | NA | 19 |
| Second-line ADT per cycle*: confirmed metastases† | £2930 | NA | NA | 19 |
| Second-line ADT per cycle*: non-metastatic† | £95 | NA | NA | 19 |
| Fistula | £4039 | £808 | γ | 21 |
| Incontinence | £2170 | £434 | γ | 21 |
| Retention | £3963 | £793 | γ | 21 |
| Lower urinary tract symptoms | £10.47 | NA | NA | 19 |
| Perineal pain | £5.16 | NA | NA | 19 |
| Haematuria | 2445 | £489 | γ | 21 |
| Urethral stricture | £3836 | £767 | γ | 21 |
| Hot flushes (per cycle) | £5.54 | NA | NA | 19 |
| Utility | ||||
| Disease-free survival | 0.774 | 0.02 | β | 41 |
| Progression: metastases | 0.42 | 0.06 | β | 36 and 42 |
| Progression: non-metastatic | 0.68 | 0.022 | β | 41 |
| Disutility for fistula | 0.15 | 0.03 | β | AA/clinical experts |
*Not probabilistic, but cost varies depending on probabilistic resource use parameters for delivery; see table 2.
†Depends on the proportion of patient in Progression state who have confirmed metastases.
ADT, androgen deprivation therapy; AA, author assumption made in conjunction with clinical experts; ICER, Incremental Cost-effectiveness Ratio; PH, proportional hazards; SC, salvage cryotherapy.