Estimated medical cost reductions associated with apixaban in real-world patients with non-valvular atrial fibrillation

Figures & data

Table 1. Relative risk and cost inputs for stroke and major bleeding (excluding intracranial hemorrhage) outcomes.

Data input	Stroke	MBEIH
Apixaban relative risk [95% CI] vs Warfarin^a	0.79 (0.66–0.95)	0.79 (0.68–0.93)
Apixaban relative risk reduction [95% CI] vs Warfarin^a	0.21 (0.05–0.34)	0.21 (0.07–0.32)
Incremental 1-year healthcare cost^b	$44,792	$35,829

CHADS₂, congestive heart failure, hypertension, age, diabetes, and stroke; CI, confidence interval; MBEIH, major bleeding excluding intracranial haemorrhage.

^aData from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial.

^bFrom Mercaldi et al.12, adjusted to 2011 dollars using the medical care component of consumer price index; stroke cost is a combined cost based on ischemic and hemorrhagic cost estimates, calculated by applying a weighted average to the separate cost estimates based on the assumption that strokes would occur in a ratio of 31 hemorrhagic to 69 ischemic.

Table 2. Baseline characteristics of NVAF patients from the Medco database compared with patients from ARISTOTLE.

Characteristic	Medco population, any Warfarin use during follow-up	ARISTOTLE^a, Warfarin
Number of patients	23,525	9081
Age, mean (SD)	74.7 (8.1)	NA
Median	78.0	70.0
Gender, n (%)
Male	13,012 (55.3)	5899 (65.0)
Female	10,494 (44.6)	3182 (35.0)
Unknown/missing	19 (0.1)	0 (0.0)
Mean CHADS2 (SD)	1.8 (1.0)	2.1 (1.1)
CHADS2
Score, n (%)
1	10,652 (45.3)	3083 (34.0)
2	7,800 (33.2)	3254 (35.8)
≥3	5,073 (21.6)	2744 (30.2)

ARISTOTLE, Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation; CHADS₂, congestive heart failure, hypertension, age, diabetes, and stroke; NA, Data not available in trial publication; n, Number of patients; NVAF, Non-valvular atrial fibrillation; SD, Standard deviation.

^aGranger et al.18

Table 3. Stroke and major bleeding (excluding intracranial hemorrhage) event rates per 100 person-years of follow-up for NVAF patients during warfarin exposure: Real-world clinical practice (Medco population) vs ARISTOTLE.

Event rate^a	Medco population (TTR unknown)	ARISTOTLE (Median TTR: 66%)^b
Stroke
Overall	5.3	1.5
CHADS2 score
1	3.7	0.9
2	5.2	1.4
≥3	9.4	2.8
MBEIH
Overall	10.0	2.3
CHADS2 score
1	8.2	1.7
2	10.5	2.4
≥3	13.5	2.9

CHADS₂, congestive heart failure, hypertension, age, diabetes, and stroke; MBEIH, major bleeding excluding intracranial hemorrhage; NVAF, Non-valvular atrial fibrillation; TTR, Time in therapeutic range.

^aEvent rates calculated per 100 person years of follow-up.

^bFor the CHADS₂ sub-groups, stroke rates are based on the combined stroke/SE outcome and MBEIH rates are calculated by subtracting rate of intracranial hemorrhage from major bleeding including intracranial hemorrhage outcome from ARISTOTLE.

Table 4. Estimated number of stroke and major bleeding (excluding intracranial hemorrhage) events avoided per 100 years of follow-up in actual clinical practice with apixaban vs warfarin.

Measure	Events avoided^a (95% CI)
Stroke
Overall	1.1	(0.3–1.8)
CHADS2
1	0.8	(0.2–1.3)
2	1.1	(0.3–1.8)
≥3	2.0	(0.5–3.2)
Age
<65	0.5	(0.1–0.7)
≥65	1.2	(0.3–1.9)
MBEIH
Overall	2.1	(0.7–3.2)
CHADS2
1	1.7	(0.6–2.6)
2	2.2	(0.7–3.4)
≥3	2.8	(1.0–4.3)
Age
<65	1.2	(0.4–1.8)
≥65	2.2	(0.7–3.4)

Note: Estimated number of events avoided (or absolute risk reduction) = estimated apixaban event rate − observed event rate during warfarin exposure (Medco population); estimated apixaban event rate = RRR for event * observed event rate.

CHADS₂, congestive heart failure, hypertension, age, diabetes, and stroke; CI, Confidence interval; NVAF, Non-valvular atrial fibrillation; MBEIH, major bleeding excluding intracranial hemorrhage; RRR, relative risk reduction.

^aper 100 person years of follow-up.

Figure 1. Incremental medical costs avoided per year with apixaban vs warfarin in real-world clinical practice for (a) stroke and (b) major bleeding excluding intracranial hemorrhage outcomes, overall and by age, CHADS₂ scores. Note: Incremental 1-year cost of stroke = $42,792, incremental 1-year cost of major bleeding = $35,829, costs adjusted to 2011 values using the medical care component of the CPI, Medical costs avoided = incremental 1-year cost of event × number of events avoided per year. MBEIH, major bleeding excluding intracranial hemorrhage.

Figure 2. Univariate sensitivity analyses examining the influence of variations in the absolute risk reduction, incremental event costs, and reference event rates on the medical cost reductions associated with avoiding (a) stroke and (b) major bleeding excluding intracranial hemorrhage events for apixaban relative to warfarin. Note: Annual cost of event varied from −30% to +30%, ARR varied using the ranges of the 95% confidence intervals of event rates from ARISTOTLE, reference event rate varied from −50% to +50% from baseline values calculated from the Medco database. ARR, Absolute Risk Reduction.

Mercaldi CJ, Ciarametaro M, Hahn B, et al. Cost efficiency of anticoagulation with warfarin to prevent stroke in medicare beneficiaries with nonvalvular atrial fibrillation. Stroke 2011;42:112-8

 PubMed Web of Science ®Google Scholar

Granger CB, Alexander JH, McMurray JJ, et al. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med 2011;365:981-92

 PubMed Web of Science ®Google Scholar