Table 1.
Data Required in the Analysis: Probabilities, Rates, and Quality of Life.
| Parameter | Value | ||||
|---|---|---|---|---|---|
| Annual Rate of Ischemic Stroke (untreated) |
Based upon CHA2DS2VASc score [see Appendix Table 2] 26 | ||||
| Efficacy of treatment with warfarin - |
0.68 8 | ||||
| aspirin – | at age 50 | 0.60 27 | |||
| at age 77 | 0.00 27 | ||||
| Probable outcome of Ischemic Stroke: |
|||||
| Death - | 0.16 28 | ||||
| Permanent sequelae : | 0.44 8 29 | ||||
| with severe disability - | 0.69 8 29 | ||||
| with mild disability - | 0.31 8 29 | ||||
| Good recovery - | 0.40 8 29 | ||||
| Annual Rate of extracranial bleeding event: (warfarin) - |
Based upon HAS-BLED score [see Table 3] 30 | ||||
| (untreated) – | (HAS-BLED bleeding rate)/2.4 31 | ||||
| (aspirin) - | (Bleeding rate in untreated) * 1.08 31 | ||||
| Annual rate ICH low risk referent group (untreated) |
0.0004 30 | ||||
| Multivariate Hazard Ratios for ICH (untreated) |
30 | ||||
| Age < 65 | 1.0 | ||||
| Age 65 – 74 | 1.97 | ||||
| Age ≥ 75 | 2.43 | ||||
| Female | 0.7 | ||||
| Prior Ischemic Stroke | 1.21 | ||||
| Hx of ICH | 8.92 | ||||
| Hx of Severe Bleed | 3.1 | ||||
| Hx of Myocardial Infarction | 0.82 | ||||
| Hx of Ischemic Heart Disease | 0.81 | ||||
| Hx of Poorly Controlled HTN † | 1.32 | ||||
| Annual rate Subdural Hematoma (untreated) |
0.00027 8 32 33 | ||||
| Location of hemorrhage | Lobar ICH | Deep ICH | Subdural hematoma |
Extracranial | |
| Relative hazard of bleeding (vs. no treatment) |
|||||
| warfarin - | 4.1 33,34 | 4.1 33,34 | 5.5 33,38,39 | 2.4 41 | |
| aspirin - | 1.84 35–37 | 1.84 35–37 | 2.0 40 | 1.08 41 | |
| Probable outcome from bleed (without warfarin/with warfarin)* |
42 | 42 | |||
| Death – | 0.19 / 0.38 | 0.21 / 0.41 | 0.26737 43 | 0.024/0.051 | |
| Severe long-term disability - | 0.43 / 0.43 | 0.44 / 0.42 | 0.07/0.09 44 | 37,43 | |
| Mild long-term disability - | 0.20 / 0.11 | 0.19 / 0.10 | 0.40/0.50 44 | ||
| Good recovery - | 0.19 / 0.08 | 0.17 / 0.07 | 0.263/0.143 | ||
| Long-term symptoms | Base-Case Value of Quality of Life | ||||
| Well | 1.0 | ||||
| Well while receiving anticoagulant therapy |
0.99 45 | ||||
| Severe long-term disability | 0.11 45 | ||||
| Mild long-term disability | 0.76 45 | ||||
| Death | 0.0 | ||||
| Short-term symptoms | |||||
| ICH‡ | 0.79 | ||||
| Ischemic stroke‡ | 0.79 | ||||
| Extracranial bleed ξ | 0.84 | ||||
| Base-Case Value of Age-Adjusted Annual Excess Mortality |
|||||
| Stroke with long-term disability | 0.08 46 | ||||
†
Poorly controlled hypertension – systolic BP ≥ 160 mmHG.
*
Assume outcomes of bleeding events for aspirin-treated patients are the same as for untreated patients.
‡
Assume quality of life is 0 for duration of hospitalization. Length of stay for specific cerebrovascular disorders except transient ischemic attack (diagnosis-related group, 14) is 6.4 days.
ξ
Length of stay for gastrointestinal hemorrhage (diagnosis-related group, 174) is 4.9 days. Duration of short-term utility loss for major extracranial bleed is 12 months.