Table a1 Model parameters

From: Cost-effectiveness of sentinel lymph node biopsy vs inguinofemoral lymphadenectomy in women with vulval cancer

Parameter

Value

Reference

Notes

Patients with metastasis

33.5% (135/403)

(van der Zee et al, 2008)

 

Age of cohort

65

 

Examined in sensitivity analysis

Probabilities of recurrence

Local recurrence

34/276 (12.3%)

(van der Zee et al, 2008)

The possibility of local recurrence is present in all arms of the model

Groin recurrence following IFL (no SLN biopsy)

1/32 (3.1%)

(Crosbie et al, 2010)

Metastasis prevalence in this study found to be 6/31. Probability of groin recurrence given metastasis=0.1615

Groin recurrence followingnegative SLN biopsy result

6/259 (2.3%)

(van der Zee et al, 2008))

Patients with unifocal vulvar disease

Groin recurrence following positive SLN biopsy and IFL

11/135 (8.1%)

(Oonk et al, 2010a, 2010b)

 

Groin recurrence following false-negative test

100%

 

By definition

Death rates following recurrence and all cause

Local Recurrence

5/34 (14.75%)

(van der Zee et al, 2008))

 

Groin Recurrence

9/11 (81.8%)

(Oonk et al, 2010a, 2010b)

 

All cause

Age 40: 0.84%

Age 65: 1.97%

Age 80: 5.85%

Office for National Statistics (2010) (downloaded 1/11/2011)

Calculated from: Natural Death rates. Mid-year estimates published 30th June 2011

Probabilities of requiring radiotherapy

With an IFL strategy One

(46.4%) 26/56

(Fonseca-Moutinho 2005)

 

After a true-positive SLN biopsy result and IFL

(41.9%) 49/117

(van der Zee et al, 2008))

 

After a false-positive biopsy result and IFL

0%

 

See assumptions

Following a recurrence if not previously administered

100%

 

See assumptions

Probabilities of morbidity in the short and long term

Time frame

Procedure

Complication

% Of patients with complications

Short term

IFL (with/without SLN biopsy)

Wound breakdown 34%

Wound cellulitis 21.3%

48.1% (22.6/47)

 

SLN biopsy

Wound breakdown 11.7%

Wound cellulitis 4.5%

15.7% (41.4/264)

Long term

IFL (with/without SLN biopsy) and RT

Lymphedema 25.5%

Recurrent erysipelas 30.6%

48.3% (23.7/49)

 

IFL (with/without SLN biopsy) no RT

Lymphedema 25.5%

Recurrent erysipelas 5.9%

29.9% (20.9/70)

 

SLN biopsy

Lymphedema 1.9%

2.3% (6.1/264)

  1. Abbreviations: H&E=haematoxylin and eosin; IFL=inguinofemoral lymphadenectomy; SLN=sentinel lymph node.
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