1. Does this tool start warfarin therapy?
No. It estimates maintenance adjustments after at least one week of therapy. First-week initiation requires closer INR monitoring and individualized clinical judgment.
Calculator inputs
Example data table
| Case | Current weekly dose (mg) | INR | Target | Estimated change | Estimated new weekly dose (mg) | Suggested recheck |
|---|---|---|---|---|---|---|
| Case A | 35.0 | 1.8 | 2.0–3.0 | +7.5% | 37.5 | 2 weeks |
| Case B | 42.0 | 3.4 | 2.0–3.0 | -7.5% | 39.0 | 2 weeks |
| Case C | 30.0 | 2.6 | 2.0–3.0 | 0% | 30.0 | 8 weeks |
Formula used
Maintenance adjustment formula: Adjusted weekly dose = current weekly dose × (1 + percent change ÷ 100).
Daily estimate: Daily average dose = adjusted weekly dose ÷ 7.
Rounded schedule: The tool rounds the weekly dose to the selected increment and distributes it across seven days.
Rule logic: The estimate uses outpatient maintenance adjustment bands tied to the measured INR, chosen target range, and clinician-style adjustment intensity.
How to use this calculator
- Enter the patient’s current weekly warfarin total and most recent INR.
- Select the therapeutic goal range used by the care plan.
- Choose maintenance therapy only after at least seven days of treatment.
- Mark any missed doses, diet changes, interactions, illness, bleeding, or procedure concerns.
- Submit the form to review the estimated weekly change, follow-up interval, and rounded seven-day schedule.
- Use the export buttons to save the result summary as CSV or PDF.
- Confirm every recommendation against the patient’s full clinical picture before acting.
FAQs
2. Can I use it when the patient is bleeding?
No. Active bleeding is a medical urgency. The tool intentionally blocks dose estimation and directs the user toward immediate clinical assessment.
3. Why does it ask about missed doses and diet changes?
Those factors can explain an out-of-range INR without requiring a large maintenance change. The notes help users review common reasons before adjusting therapy.
4. What does adjustment style change?
It selects the lower end, midpoint, or upper end of the adjustment band. That helps model cautious, typical, or stronger maintenance responses.
5. Why is the seven-day schedule rounded?
Real dosing plans often need practical tablet-friendly numbers. Rounding gives a workable weekly pattern while staying close to the estimated total dose.
6. Does this handle every target INR?
No. It supports the two most common maintenance ranges in the built-in logic: 2.0 to 3.0 and 2.5 to 3.5.
7. Should a stable patient always get a dose change?
Not always. When the INR is only slightly out of range and recent readings were stable, a clinician may reasonably keep the same weekly dose.
8. Is this a prescribing decision tool?
No. It is an educational decision-support page. Final dosing decisions must be confirmed by a qualified clinician who knows the full case.