INR and coagulation monitoring eCRF template
Anticoagulation data is a series, not a single value: each INR with its date, method and the dose decision that followed. This template records INR measurements as repeating rows so time in therapeutic range can be calculated and dosing reviewed.
- Repeating INR rows
- Method and dose recorded
- Per-row audit trail
Free sandbox · No credit card · 21 CFR Part 11 aligned
Measurements
14
In range
10 / 14
Last INR
2.4
At a glance
- The international normalised ratio (INR) standardises prothrombin time for monitoring vitamin K antagonists such as warfarin.
- A target range of 2.0 to 3.0 applies to most indications; some mechanical heart valves use higher targets. Record the target per participant.
- Time in therapeutic range (TTR), often calculated by linear interpolation between measurements, is a key quality measure in anticoagulation trials.
- Record the method (laboratory or point-of-care device), because results can differ.
- Bleeding events are commonly classified with ISTH criteria for major and clinically relevant non-major bleeding.
In trials
Why the log matters
In trials comparing a new anticoagulant with warfarin, the quality of warfarin control in the comparator arm shapes the result: a poorly controlled comparator makes any new drug look better. Regulators and readers look at the comparator arm's TTR, which needs every INR with its date. The same log supports safety review when bleeding or clotting events occur.
Trials of other drugs also collect coagulation data, for example when a new treatment might interact with anticoagulants or affect liver function. There, INR, PT and aPTT appear as safety labs at defined visits. See the lab results eCRF template.
Calculating TTR
The common method assumes INR changes linearly between measurements and calculates the proportion of days within range. It needs complete dates and values, and a rule for gaps longer than a set number of days. Define the method in the analysis plan and calculate it there.
Template
INR log fields (one row per measurement)
| Field | Content |
|---|---|
| Date and time | When the sample was taken |
| INR | Numeric result |
| Method | Laboratory or point-of-care device |
| Target range | Low and high target for this participant |
| Current weekly dose | Anticoagulant dose at the time of the test |
| Dose change | None, increased, decreased, held |
| Reason for out-of-range value | Missed dose, interacting drug, diet, illness, unknown |
Add PT and aPTT columns for safety monitoring studies as needed.
In Capture
Repeating rows, each with its own audit trail
INR measurements go in a table section, one row per test. Each row carries its own field-level audit trail, and range checks raise an auto-query when a value falls outside the limits you set, so out-of-range results and possible unit or entry errors are confirmed quickly.
- Table section for repeating tests.
- Per-row audit trail.
- Range checks with auto-queries.
Edit checks / auto-queries
2Type
Range High
Operator
Greater than
Value
180
Priority: High
Type
Range Low
Operator
Less than
Value
80
Priority: Normal
Query raised automatically
Value 192 violates limit (180). Please verify.
Build an INR log
Add a table section and range checks in the free sandbox.
Safety
Bleeding events alongside the log
Bleeding is the main safety concern with anticoagulants, and trials classify it in a standard way, commonly as major, clinically relevant non-major or minor using ISTH definitions. Record each bleeding event on the adverse event form with the fields the classification needs: site of bleeding, haemoglobin drop, transfusion, need for intervention, and outcome. Link it to the INR closest in time.
Many anticoagulation trials also use an independent committee to adjudicate bleeding and thrombotic events. Keep the investigator-reported classification and the adjudicated result as separate variables. See the adverse event eCRF template.
Point-of-care
Point-of-care and home testing
Many anticoagulation clinics and some trials use point-of-care INR devices at the site or at home. They give immediate results, which helps dosing decisions, but they need quality control, and results at the extremes of the device's range may need laboratory confirmation. Record the device and whether a result was confirmed.
When participants self-test at home, decide how results reach the study: reported to the site and entered, or recorded by the participant. Either way, the date and value of each test and the resulting dose decision should end up in the same log. See patient diary software.
Before go-live
INR log checklist
Target range per participant
Recorded at baseline.
Method recorded
Laboratory or point-of-care.
Dose and changes
Weekly dose and each change.
TTR method
Defined in the analysis plan.
Bleeding classification
ISTH fields on the AE form.
Range checks
For implausible values.
Can point-of-care INR results be recorded?
Yes. Record the device and whether the result was confirmed by a laboratory.
Can participants self-test at home?
Yes, if the protocol allows it. Decide how results reach the study log.
What is a normal INR target?
For most indications on warfarin, 2.0 to 3.0. Some mechanical heart valves use higher targets. Record the target for each participant.
What is time in therapeutic range?
The proportion of time a participant's INR is within the target range, commonly calculated by linear interpolation between measurements.
Why record the INR method?
Point-of-care devices and laboratory tests can give different results.
Can each INR measurement have its own audit trail?
Yes. Each row in a table section carries its own field-level audit trail.
Does Capture calculate TTR?
The log records every value and date; TTR is calculated in analysis with the method in your analysis plan.
Is the template free?
Yes. Copy it into your study in the free sandbox.
Keep exploring
Related pages
Every INR, every dose decision
Repeating logs with a per-row audit trail. Free sandbox.