Economic evaluation of pharmacological treatments for overactive bladder from the perspective of the UK National Health Service

Figures & data

Table 1. Resource use and costs.

Resource	On treatment, controlled	On treatment, not controlled	Off treatment
Use
GP visits per month (n)	0	1	0.08
Specialist visits per month (n)	0	0.25	0.33
Use of incontinence pads (%)	10	50	50
Pads/day (n)	2.5	5.5	5.5
Lifetime risk of secondary intervention (%)	0	0	20
Costs
GP visit*	£38.8331^,32
Specialist visit	£103.0033
Incontinence pad	£0.25
Secondary intervention	£7321.00†32^,38

*A GP visit is assumed to occur when a patient switches treatment.

†All patients are screened for sacral nerve stimulation and undergo percutaneous nerve evaluation, with only those showing a satisfactory response proceeding to a permanent implant. It is assumed that 50% of patients obtain sufficient improvement to proceed to permanent implant, with the remaining patients receiving two BTX injections per 6-month period.

BTX, botulinum toxin; GP, general practitioner.

Table 2. Efficacy inputs.

Drug and dose	No incontinence episodes (%)	<8 micturitions/day (%)	Controlled (%)
Mirabegron 50 mg	12.56	28.47	3.58
Solifenacin 5 mg, branded	15.92	31.14	4.96
Solifenacin 10 mg, branded	15.97	35.21	5.62
Oxybutynin (ER) 10 mg, generic	10.96	27.00	2.96
Tolterodine (ER) 4 mg, generic	11.57	26.81	3.10

ER, extended release.

Table 3. Drug costs*.

Drug and dose	Generic or branded	Price per month*
Mirabegron 50 mg	Branded	£29.00
Solifenacin 5 mg	Branded	£27.62
Solifenacin 10 mg	Branded	£35.91
Oxybutynin 10 mg	Generic	£6.55
Tolterodine 4 mg (ER)	Generic	£27.62

*Drug costs sourced from British National Formulary 64 (2012)29; all costs calculated for 30 days.

ER, extended release.

Table 4. Probabilities of and cost of managing comorbidities34.

Comorbidity	On treatment, controlled	On treatment, not controlled	Off treatment
Probabilities per month
Fall leading to fracture (%)	0.0042	0.0090	0.0090
Depression (%)	0.0139	0.0342	0.0342
Skin or urinary tract infection (%)	0.0532	0.0754	0.0754
Costs
Fall leading to fracture	£362.0033
Depression	£102.7732^,34^,35
Skin or urinary tract infection	£2.8932^,34^,35

Figure 1. Treatment sequences compared. ER, extended release; IR, immediate release.

Table 5. Patient outcomes per 1000 patients treated.

Outcome	Standard treatment sequence	New treatment sequence	Difference
Patients controlled (no incontinence episodes and <8 micturitions per 24 h [n])	29.6	38.7	9.2
Number needed to treat to achieve one controlled patient	33.8	25.8	−8.0
Patients with no incontinence episodes per 24 h (n)	103.6	123.7	20.1
Patients with <8 micturitions per 24 h (n)	228.7	262.1	33.4

Table 6. Cost and resource use per 1000 patients treated.

	Resource use			Cost (£)
Resource	Standard treatment sequence	New treatment sequence	Difference	Standard treatment sequence	New treatment sequence	Difference
Pads used (n)	977,517	970,854	−6663	244,379	242,713	−1666
GP visits (n)	11,153	11,197	44	433,056	434,775	1719
Specialist visits (referrals) (n)	3041	2990	−51	313,188	307,934	−5255
Surgical interventions (n)*	18	12	−7	133,811	84,684	−49,128
Co-morbidities (n)	14.07	14.03	−0.04	827	823	−3
AEs (n)†	609	279	−330	0	0	0
Mean months on therapy (n)	10.42	10.78	0.36	174,204	314,433	140,228
Total				1,299,466	1,385,361	85,895

*Assumes that 50% of patients receive BTX and 50% undergo sacral nerve stimulation.

†The AEs considered were dry mouth, constipation, and blurred vision; the cost of managing these events was assumed to be £0.

AEs, adverse events; BTX, botulinum toxin; GP, general practitioner.

Figure 2. Tornado diagram showing results of the deterministic sensitivity analysis in which each parameter was separately varied by 20%. (a) Percentage change in incremental number of controlled patients; (b) percentage change in incremental costs.

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