Cost-effectiveness of solifenacin compared with oral antimuscarinic agents for the treatment of patients with overactive bladder in the UK

Figures & data

Table 1. Model inputs for adverse events, treatment pathways, and utilities.

Parameter	Base-case value	Deterministic sensitivity analysis values	Source
Adverse events, %^a
Dry mouth
Solifenacin 5 mg	14.3	10.2–18.4	Astellas [22]
Tolterodine ER 4 mg	14.9	12.8–17.8	Nazir et al. [13]
Fesoterodine 4 mg	15.1	12.2–19.3	Nazir et al. [13]
Fesoterodine 8 mg	28.9	24.8–33.7	Nazir et al. [13]
Oxybutynin ER 10 mg	21.0	16.3–27.2	Nazir et al. [13]
Oxybutynin IR 10 mg	37.1	26.4‒51.0	Nazir et al. [13]
Solifenacin 10 mg	27.5	24.3–30.9	Nazir et al. [13]
Tolterodine IR 4 mg	22.3	18.1–25.7	Nazir et al. [13]
Trospium chloride 60 mg	12.7	7.7‒18.5	Nazir et al. [13]
Constipation
Solifenacin 5 mg	7.2	4.2–10.2	Chapple et al. [10]
Tolterodine ER 4 mg	4.3	3.0–6.2	Nazir et al. [13]
Fesoterodine 4 mg	3.7	2.4–5.8	Nazir et al. [13]
Fesoterodine 8 mg	6.9	4.8‒10	Nazir et al. [13]
Oxybutynin ER 10 mg	3.7	1.7–7.5	Nazir et al. [13]
Oxybutynin IR 10 mg	3.7	2.1–6.4	Nazir et al. [13]
Solifenacin 10 mg	12.2	9.9–15	Nazir et al. [13]
Tolterodine IR 4 mg	3.7	1.7–7.5	Nazir et al. [13]
Trospium chloride 60 mg	15.1	8.1‒27.7	Nazir et al. [13]
Treatment pathways
Monthly probability of treatment discontinuation, %
Without adverse events
Solifenacin 5 mg/day	6.8	3.4–10.2	Calculated from Chapple et al. [24] and Castro-Diaz et al. [23]
Other antimuscarinics	6.8	3.4–10.2	Assumption
With adverse events	90.0	50.0–100.0	Assumption
Monthly probability of treatment switch after discontinuation, %	26.1	6.7–39.1	Odeyemi et al. [25];^b assumption
Monthly probability of treatment restart, %	5.6	0–8.42	Assumption^c
Monthly probability of BTX-A injection, %	0.1	0–0.05	Assumption
Probability of reinjection after 6 months, %	70.0	50.0–100.0	Assumption
Utilities^d
Micturition			Aballéa et al. [14]
Level 1	0.0632	0.0453–0.0811
Level 2	0.0422	0.0258–0.0587
Level 3	0.0204	0.0045–0.0363
Level 4	0.0104	–0.0316
Incontinence			Aballéa et al. [14]
Level 1	0.0586	0.0422–0.0749
Level 2	0.0437	0.0271–0.0602
Level 3	0.0314	0.0142–0.0486
Level 4	0.0128	–0.0369
Decrement for adverse events	–0.0357	0 to – 0.1	Aballéa et al. [14]

BTX-A, botulinum toxin type A; ER, extended release; IR, immediate release.

^aProbability at 3 months. ^bBased on switching among patients on tolterodine. ^cA monthly probability of 5.6% (50% annually) was assumed for restarting treatment among patients who discontinued treatment without immediately switching to another drug. It was assumed that one-third of these patients would go back to their previous treatment, and one-third each would receive next line A and next line B. ^dCoefficients for symptom severity level relative to symptom level 5, e.g. the utility of patients at micturition severity level 1 is higher than the utility of patients with micturition severity level 5 by 0.0632.

Table 2. Model inputs for resource use and costs.

Parameter	Base-case value	Deterministic sensitivity analysis values	Source
Resource use
Pad utilization, number per month^a			Astellas [33]
Level 1	6.97	5.83–8.10
Level 2	23.48	20.80–26.16
Level 3	44.47	39.76–49.18
Level 4	58.13	52.10–64.15
Level 5	121.30	111.88–130.72
GP consultations	1 visit at treatment initiation and BTX-A;	0‒2	Assumption
Specialist consultations	1 visit at treatment initiation and BTX-A;	0‒2	Assumption
Costs
Monthly acquisition costs
Solifenacin 5 mg	£28.00	‒	BNF [28]
Tolterodine ER 4 mg	£28.01	‒	BNF [28]
Fesoterodine 4 mg	£28.01	‒	BNF [28]
Fesoterodine 8 mg	£28.01	‒	BNF [28]
Oxybutynin ER 10 mg	£27.92	‒	BNF [28]
Oxybutynin IR 10 mg	£2.40	‒	BNF [28]
Solifenacin 10 mg	£36.41	‒	BNF [28]
Tolterodine IR 4 mg	£2.88	‒	BNF [28]
Trospium chloride 60 mg	£25.04	‒	BNF [28]
GP consultation (first visit)	£65.00	‒	Curtis & Burns [29]
GP consultation (follow-up)	£27.00	‒	Curtis & Burns [29]
Specialist visit (first visit or follow-up)	£94.00	‒	Department of Health [30]
BTX-A injection/reinjection	£1,151.98^b	‒	BNF [28]; Curtis & Burns [29]; Department of Health [30]
Incontinence pad	£0.17	‒	AgeUK incontinence [31]

BTX-A, botulinum toxin type A; ER, extended release; GP, general practitioner; IR, immediate release.

^aAccording to incontinence symptom severity level. ^bBotox® Allergan 100 unit vial + intermediate endoscopic bladder procedure + nurse review.

Table 3. Cost-effectiveness analysis of solifenacin 5 mg/day compared with other oral antimuscarinic agents at 5 years (base-case scenario).

	Primary analysis		Secondary analysis
	Solifenacin 5 mg/day	Tolterodine ER 4 mg/day	Fesoterodine 4 mg/day	Fesoterodine 8 mg/day	Oxybutynin ER 10 mg/day	Oxybutynin IR 10 mg/day	Solifenacin 10 mg/day	Tolterodine IR 4 mg/day	Trospium chloride 60 mg/day
Cost, £
Drug acquisition	267	280	283	205	249	16	250	25	211
Other OAB drug(s)	359	355	354	376	363	381	380	365	367
GP visits	206	204	204	212	207	213	213	208	209
Specialist visits	446	443	443	459	450	463	462	451	453
Botulinum toxin	136	134	133	145	138	147	147	139	140
Incontinence pads	320	339	331	339	330	334	327	340	322
Total costs, £	1,733	1,756	1,748	1,736	1,737	1,554	1,778	1,528	1,702
Total QALYs	3.732	3.725	3.727	3.723	3.728	3.724	3.728	3.723	3.730
Incremental costs, £	‒	–23	‒15	‒3	‒5	179	‒46	205	31
Incremental QALYs	‒	0.0066	0.0043	0.0089	0.0033	0.0080	0.0041	0.0085	0.0020
ICER, £ per QALY gained	‒	Dominant	Dominant	Dominant	Dominant	22,393	Dominant	23,975	15,007

ER, extended release; GP general practitioner; ICER, incremental cost-effectiveness ratio; IR, immediate release; OAB, overactive bladder; QALY, quality-adjusted life year.

Figure 1. Deterministic sensitivity analysis: Tornado diagram showing the effects of varying key input parameters on (A) costs and (B) QALYs for solifenacin 5 mg/day versus tolterodine ER 4 mg/day.

AE, adverse event; BTX-A, botulinum toxin type A; discon, discontinuation; ER, extended release; ICER, incremental cost-effectiveness ratio; QALY, quality-adjusted life year; prob, probability; soli, solifenacin; tolt, tolterodine; Tx, treatment; w/o, without; 2L, second-line.

Figure 2. Probabilistic sensitivity analysis: (A) cost-effectiveness plane and (B) cost-effectiveness acceptability curve for solifenacin 5 mg/day versus tolterodine ER 4 mg/day.

ER, extended-release; ICER, incremental cost-effectiveness ratio; QALY, quality-adjusted life year.

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