Time in Therapeutic Range (TTR) Calculator

Estimate time in therapeutic range for anticoagulation or similar monitoring programs and benchmark performance against target and risk thresholds.

Count of monitored days when values were within the prescribed therapeutic interval.
Total days in the monitoring period for the patient cohort or individual case.
Optional benchmark. Defaults to 65% if blank.
Optional risk flag threshold. Defaults to 50%.

This calculator is for analytical support and does not replace individualized medical assessment.

Examples

  • Days in range 195, total monitored days 270, target 65%, alert threshold 50% => Time in therapeutic range: 72.22%. Target: 65.00%. Gap: +7.22% vs target. Alert threshold (50.00%): At or above alert threshold.
  • Days in range 84, total monitored days 180, optional fields blank => Time in therapeutic range: 46.67%. Target: 65.00%. Gap: −18.33% vs target. Alert threshold (50.00%): Below alert threshold.

FAQ

Can this be used for clinic-level reporting?

Yes. Aggregate days in range and total monitored days across patients for a population-level TTR estimate, then stratify by regimen or site.

Is this the Rosendaal interpolation method?

No. This implementation is a day-count ratio approach and should be interpreted accordingly in studies that require interpolation-based TTR.

What does the alert threshold indicate?

It provides a configurable screening boundary for low-control situations that may require review of dosing protocols or follow-up cadence.

Additional Information

  • TTR is expressed as a percentage of monitored time within the therapeutic interval.
  • If target TTR is left blank, the calculator uses 65.00% as a default benchmark.
  • If alert threshold is left blank, the calculator uses 50.00% to flag elevated control risk.

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