Warfarin monitoring economic evaluation of point of care self-monitoring compared to clinic settings

Figures & data

Figure 1. Structure of economic model.

Table 1. Two-year clinical event rates for all patients, AF only, and MHV only^a.

	PST/PSM			Usual care
	n	Cohort	Rate	n	Cohort	Rate
All patients
Thrombosis	114	3053	3.7%	152	2939	5.2%
Major hemorrhage	230	3216	7.2%	244	3101	7.9%
Died	247	3071	8.0%	274	2956	9.3%
AF-only patients
Thrombosis	70	1629	4.3%	69	1623	4.3%
Major hemorrhage	126	1676	7.5%	119	1677	7.1%
Died	138	1555	8.9%	156	1549	10.1%
MHV-only patients
Thrombosis	36	1132	3.2%	63	1040	6.1%
Major hemorrhage	78	1111	7.0%	91	1015	9.0%
Died	64	1101	5.8%	75	1002	7.5%

^aSource: Heneghan et al.6

Table 2. Event rates with warfarin.

	n	%
Stroke fatal	71	19.1%
Major stroke	60	16.2%
Minor stroke	92	24.8%
Systemic embolism	22	5.9%
MI	126	34.0%
Total	371	100.0%
Major bleed non-fatal	331	22.8%
Non-major bleed	1063	73.4%
Total	1394	100.0%

Table 3. Two-year clinical events for total population, MHV patients only, and AF patients by PST/PSM and usual care.

	Total population		MHV only
	PST/PSM	Usual care	PST/PSM	Usual care	AF PST/PSM and usual care
Major stroke	0.44%	0.84%	0.52%	0.98%	0.69%
Minor stroke	0.67%	1.28%	0.79%	1.50%	1.05%
Fatal stroke	0.51%	0.99%	0.61%	1.16%	0.81%
Myocardial infarction	0.92%	1.76%	1.08%	2.06%	1.44%
Major hemorrhage	1.48%	1.90%	1.57%	2.00%	1.67%
Minor hemorrhage	4.76%	6.10%	5.05%	6.42%	5.38%
Systemic embolism	0.16%	0.31%	0.18%	0.36%	0.25%
All cause mortality	7.44%	9.30%	3.87%	9.30%	9.29%

Table 4. Warfarin monitoring costs, usual care 2012/13 prices.

Warfarin monitoring	Cost	Patients
Primary care	£231.33	20%
Secondary care	£317.90	80%

Table 5. Annual warfarin self-monitoring costs, 2012/13 prices.

	Self-test costs		Self-manage costs
Patient pathway item	First year	Later years	First year	Later years
Education and training by practice nurse, £43 per hour19	£86.00	£0.00	£172.00	£0.00
CoaguChek XS device	£399.00	£0.00	£399.00	£0.00
Test strips: self-test every 2 weeks plus QA	£78.50	£78.50	£78.50	£78.50
Clinic review every 6 months (20% of self-manage see GP-nurse; 80% a clinic nurse)	£17.90	£17.90	£17.90	£17.90
Monthly call to adjust dose	£66.00	£66.00	£0.00	£0.00
Total cost	£647.20	£162.40	£667.20	£96.40

Table 6. Costs of adverse events, 2012/13 prices.

Adverse event	Cost	Source
Major stroke year 1	£15,594	Minor stroke17 plus 34.4 days in hospital20 and 14 days rehabilitation13
Minor stroke year 1	£3,082	NHS Reference Costs for AA22A and AA22B non-elective admissions17
Stroke years 2–5	£2,430	Costing template NICE14
Fatal stroke	£400	NICE submission13
Major bleed	£1,173	Costing template NICE14
MI	£1,967	NHS Reference Costs for EB10Z non-elective admissions17

Table 7. Utilities associated with adverse events.

Event	Utility	Source
Stable AF	0.779	Berg et al. (2010)^21
Major stroke	0.189	Robinson et al. (2001)^22
Post-major stroke	0.482	Hallan et al. (1999)^23
Major bleed	0.599	Sullivan et al. (2006)^24
MI	0.683	Lacey and Walters (2003)^25

Table 8. Ten-year results—total.

	PST/PSM	Usual care	Incremental
Total cost	£19,128,390	£30,998,975	−£11,870,585
Total cost (per patient)	£1,913	£3,100	−£1,187
Total QALYs (per patient)	4.470	4.194	0.276
Incremental cost per QALY			Dominant
Major stroke events	139	228	−89
Myocardial infarction	292	480	−188
Major hemorrhage	579	672	−93
Systemic embolism	51	84	−33
Died	3169	3781	−612

Table 9. Sensitivity analyses.

	Value in sensitivity analysis	Incremental cost	Change from baseline (minus = increase saving)
Baseline		−£1,187
Major stroke: −25% change cost	£11,695	−£1,163	£24
Major stroke: +25% change cost	£19,492	−£1,211	−£24
Stroke years 2–5: −25% change cost	£1,823	−£1,146	£41
	£3,038	−£1,228	−£41
Stroke years 2–5: +25% change cost
Patient transport for:	0% of people	−£1,144	£43
	10% of people	−£1,230	−£43

Table 10. Ten-year results—MHV patients only.

	PST/PSM	Usual care	Incremental
Total cost	£21,128,506	£44,284,107	−£23,155,601
Total cost (per patient)	£2,112.85	£4,428.41	−£2,316
Total QALYs (per patient)	4.711	4.453	0.258
Incremental cost per QALY			Dominant
Major stroke	177	307	−130
Myocardial infarction	391	648	−257
Major hemorrhage	654	738	−85
Systemic embolism	71	122	−52
Died	2312	2818	−507

Table 11. Ten-year results—AF patients only.

	PST/PSM	Usual care	Incremental
Total cost	£20,595,605	£24,828,663	−£4,233,058
Total cost (per patient)	£2,059.56	£2,482.87	−£423
Total QALYs (per patient)	4.222	4.222	0.000
Incremental cost per QALY			Cost saving

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