CurrentAetnaPolicy 0173

Prothrombin Time (INR) Home Testing Devices

Policy governing medical necessity, coverage, and coding for home prothrombin time (INR) testing devices for members on chronic warfarin anticoagulation and related device training/management.

Policy Summary

PayerAetna

PolicyProthrombin Time (INR) Home Testing Devices

Policy CodePolicy 0173

Change TypeNo material changes

Effective DateSep 22, 1997

Next Review DateFeb 8, 2024

Key ActionPrescribe home PT monitor, ensure patient training and document demonstrated correct device use prior to home use.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

≥3min prior anticoagulation (months)

≥6min expected duration (months)

once/weekmax testing frequency

03/28/2023last review

Coverage Criteria

Medical Necessity (Covered Indications)

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Covered when ALL of the following are met:

Core coverage criteria: 1. Expected need for home INR testing is 6 or more months; 2. The person must have been anticoagulated for at least 3 months prior to use of the home INR devices; 3. Self-testing with the device should not occur more frequently than once a week.see node text

Devices are covered as durable medical equipment for persons who require chronic oral anticoagulation for specified indications (mechanical heart valve, ventricular assist device, chronic atrial fibrillation, deep venous thrombosis, pulmonary embolism, venous embolism and thrombosis of deep vessels of lower extremity, or hypercoagulable states).

Testing frequency guidance

Coverage considerations regarding testing frequency:

Weekly testing guidance: For patients beyond the initial titration period, testing more than once weekly is generally unnecessary due to warfarin pharmacokinetics (half-life ~1.5 days; 3-4 half-lives to steady state).<= 1 test/week typically sufficient

If clinical destabilization occurs (eg new interacting medication), more direct physician attention is recommended rather than routine increased home testing.

PSM with criteria-driven interactions

Use of home INR devices in patient self-management programs:

Criteria-driven PSM program: PSM programs utilizing telemedicine and point-of-care devices that apply predefined criteria (e.g., INR < 1.8, INR > 4.5, weekly warfarin dose change > 1.25 mg, missing INR or dosage) for triggering interactions can maintain treatment effect and safety while reducing interactions.criteria as listed

Based on a randomized trial of 87 patients showing comparable INR control and fewer interactions (PSM 1.1 vs PST 4.2 interactions/month).

Aetna considers prothrombin time home testing units experimental and investigational for all indications other than those specifically listed as covered (for example, arterial embolism to the eye, atrial flutter, and Kawasaki disease). The effectiveness of home PT/INR devices for indications outside the covered list has not been established, and such use is therefore not supported by this policy.

Additional hardware or software required solely to download data from home PT/INR units to a computer for anticoagulation management are considered not medically necessary convenience items and are not covered under this policy.

The referenced Medicare Decision Memorandum addresses only home testing and concludes that, because warfarin has a half-life of about 1.5 days and requires roughly 3–4 half-lives to reach steady state, testing more than once weekly is generally unnecessary for patients beyond the initial titration period. The memorandum also notes that if a patient becomes clinically destabilized (for example, after starting a medication that alters warfarin metabolism), increased physician-directed attention rather than routine increased home testing may be appropriate.

Examples of ICD‑10 codes mentioned in this policy as associated with covered indications include codes for thrombophilia (eg, D68.51–D68.62), pulmonary embolism (eg, I26.01–I26.99), and atrial fibrillation (eg, I48.0, I48.11, I48.19, I48.20, I48.21, I48.91). The policy also lists examples of codes that are not covered for the indications in this CPB, such as H34.9 (arterial embolism to the eye), I48.3/I48.4/I48.92 (atrial flutter), and M30.3 (Kawasaki disease).

Covered Indications

Chronic oral anticoagulation with warfarin for mechanical heart valve, VAD, chronic AF, DVT/PE, venous embolism/thrombosis of lower extremity, or hypercoagulable states

All core medical necessity criteria must be met for coverage of home INR devices for these indications:

Covered indications (warfarin-dependent conditions): Chronic oral anticoagulation with warfarin for one or more of the following: mechanical heart valve, ventricular assist device, chronic atrial fibrillation, deep venous thrombosis, pulmonary embolism, venous embolism and thrombosis of deep vessels of lower extremity, or hypercoagulable states (e.g., antithrombin III deficiency, Factor V Leiden, protein C deficiency, protein S deficiency).

Coverage applies when the medical necessity criteria (expected need >=6 months; >=3 months prior anticoagulation; testing frequency <= once weekly) are satisfied.

Long-term anticoagulation management with warfarin using home INR monitoring devices for patients capable of self-testing or self-management

Long-term anticoagulation management with home INR monitoring is covered when patients are capable of self-testing or self-management and program requirements are met:

PSM/PST program criteria: Patients capable of self-testing or self-management may use home INR monitoring as part of long-term warfarin management; programs that employ predefined, criteria-driven interactions (eg thresholds for INR, dose-change, or missing data) can reduce routine interactions while maintaining safety.see program criteria (eg INR <1.8, INR >4.5, weekly dose change >1.25 mg)

Routine home testing beyond the initial titration period should generally not exceed once weekly; destabilized patients may require more direct physician attention rather than increased routine home testing.

Frequency Limits

Denial Risk

Denial risk for non-covered items

Denial risk: Claims for home INR self-testing that document testing more frequently than once per week for patients beyond the initial titration period are at risk for denial unless clinical documentation supports a destabilizing event requiring physician-directed increased monitoring. Ensure documentation of the clinical rationale (e.g., recent medication change affecting warfarin metabolism, acute illness) and direct physician management when billing more frequent home testing.

Affected scenarios: routine home self-testing >1 time/week for stable patients.
Required documentation: evidence of clinical destabilization and treating physician plan for increased monitoring.
Billing note: frequency limit refers specifically to home testing devices; more frequent INR checks may be performed in-clinic per physician direction.

Coding

Covered CPT Codes (if selection criteria met)CPTCovered

93792	Patient/caregiver training for initiation of home international normalized ratio (INR) monitoring; face-to-face, including use and care of the INR monitor, obtaining blood sample, instructions for reporting home INR test results, and documentation of patient's/caregiver's ability to perform testing and report results.
93793	Anticoagulant management for a patient taking warfarin; includes review and interpretation of a new home, office, or lab INR test result, patient instructions, dosage adjustment (as needed), and scheduling of additional test(s), when performed.

Covered HCPCS Codes (if selection criteria met)HCPCSCovered

G0248	Demonstration, prior to initial use, of home INR monitoring for patient meeting Medicare coverage criteria; includes face-to-face demonstration of use and care of the INR monitor, obtaining at least one blood sample, provision of instructions for reporting home INR test results, and documentation of patient ability to perform testing prior to its use.
G0249	Provision of test materials and equipment for home INR monitoring; includes provision of materials for use in the home and reporting of test results to physician; not occurring more frequently than once a week.
G0250	Physician review, interpretation and patient management of home INR testing; includes face-to-face verification by the physician that the patient uses the device in the context of anticoagulation management following initiation of home INR monitoring; not occurring more frequently than once a week.

Covered ICD-10 Codes (if selection criteria met)ICD-10Covered

D68.51 - D68.62	Thrombophilia (Antithrombin III deficiency, Factor V Leiden, Protein C deficiency, Protein S deficiency).
I26.01 - I26.99	Pulmonary embolism.
I27.82	Chronic pulmonary embolism.
I48.0, I48.11, I48.19, I48.20, I48.21, I48.91	Atrial fibrillation.
I80.00 - I80.9	Phlebitis and thrombophlebitis of upper and lower extremities and unspecified site.
I82.401 - I82.5Z9	Embolism and thrombosis of deep veins of lower extremity.
I82.621 - I82.629	Acute embolism and thrombosis of deep veins of upper extremity.
I82.721 - I82.729	Chronic embolism and thrombosis of deep veins of upper extremity.
T80.0XX+	Complications of infusion, transfusion and therapeutic injection (codes included where applicable).
T81.718+	Other complications of procedures, not elsewhere classified (specific codes as applicable).

1–10 of 15

1/2

ICD-10 Codes Not Covered for Indications ListedICD-10Not Covered

H34.9	Unspecified retinal vascular occlusion (arterial embolism to the eye).
I48.3, I48.4, I48.92	Atrial flutter (not covered indication).
M30.3	Mucocutaneous lymph node syndrome (Kawasaki disease) (not covered).

Provider Actions

Prior Authorization

Codes requiring coverage criteria and training (93792/93793; G0248–G0250)

Coverage of patient training and management services requires that selection criteria are met; CPT codes 93792 and 93793 and HCPCS codes G0248–G0250 are covered when selection criteria and training/provision requirements are satisfied.

CPT 93792 — patient/caregiver training for initiation of home INR monitoring (face-to-face) including documentation of ability to perform testing
CPT 93793 — anticoagulant management including review/interpretation of INR, instructions, dose adjustment, and scheduling of tests
HCPCS G0248 — demonstration prior to initial use (face-to-face) with documentation of ability to perform testing
HCPCS G0249 — provision of test materials/equipment (not occurring more frequently than once a week)
HCPCS G0250 — physician review/interpretation and management (not occurring more frequently than once a week)

Billing Rule

Testing frequency and payer notification per Medicare guidance

The Medicare Decision Memorandum states testing more than once weekly is generally unnecessary beyond initial titration; providers should ensure clinical justification for more frequent home testing and follow plan rules for payer notification or prior authorization as needed.

Given warfarin pharmacokinetics, routine home testing >1x/week is not generally necessary after titration
If clinical destabilization or new interacting medication occurs, physician-directed attention is recommended

Step Therapy

Step therapy — not applicable

Step therapy is not specified in this policy; no step therapy requirements apply to home INR monitoring in this document.

Note

Criteria-driven interaction workflow for PSM

Use of predefined criteria-driven telemedicine surveillance (eg INR <1.8, INR >4.5, weekly warfarin dose change >1.25 mg, missing INR or dosage) can trigger interactions and reduce routine contacts while maintaining safety and treatment effect.

Example criteria from RCT: INR <1.8 or >4.5, weekly warfarin dose change >1.25 mg, missing INR or dosage
PSM with criteria-driven interactions reduced interactions from ~4.2 to ~1.1 per month without adverse effects

Documentation Required

Prescriber responsibility and training documentation

The prescribing physician must prescribe the home PT/INR monitor and is responsible for patient training and ongoing management; documentation should show the patient completed an educational program and demonstrated correct device use prior to home use.

Physician prescribes device and provides/oversees training
Patient must complete an educational program and demonstrate correct use before home testing

Documentation Required

Policy history and review date documentation

Record administrative policy history and review dates in administrative records; the policy's last review and next review dates are part of the documented history.

Last review: 03/28/2023; Effective date: 09/22/1997; Next review: 02/08/2024

Denial Risk

Denial risk — data download hardware/software considered not medically necessary

Additional hardware or software needed to download data from home INR units to computers is considered not medically necessary and may be denied as a convenience item outside the covered device provision.

Coverage is limited to the home testing device and associated training/management; downloading systems are not covered

Prior Authorization

Ordering requirement — document rationale for >1/week testing or provide direct physician attention

If a patient experiences destabilizing clinical changes (eg new interacting medication) they should receive direct physician attention; clinicians who order home INR testing more frequently than once weekly must document the clinical rationale.

Destabilized patients may benefit from physician-directed care rather than increased routine home testing
Document clinical justification when ordering testing more frequently than once per week

Documentation Required

Ordering requirement — devices by prescription; prescriber manages training and follow-up

Home INR monitors are available by prescription for home use under a physician’s supervision; the prescribing physician is responsible for training and ongoing patient management.

Devices are available by prescription and intended for use under physician supervision
Physician responsible for training and ongoing management of users

Ordering Requirements

Documentation Required

Ordering requirements — prescription and prescriber responsibility

Home INR monitoring devices are available only by prescription and the prescribing physician must provide training and ongoing management, with patient demonstration of correct device use prior to home use.

Physician supervision required; patient must demonstrate correct device use after educational program

Prior Authorization

Ordering requirements — handle destabilized patients with physician-directed care and document if ordering >1/week

Patients with destabilizing clinical changes should receive direct physician attention; clinicians ordering testing more frequently than once weekly should document the clinical justification for increased frequency.

Medicare NCD applies to home testing; destabilized patients may need more direct care
Document rationale for increased testing frequency when outside typical once-weekly limit

Not Covered / Exclusions

Home INR devices are not covered when used for indications other than the policy’s specified covered conditions. Examples of such non‑covered indications include arterial embolism to the eye (H34.9), atrial flutter (I48.3, I48.4, I48.92), and Kawasaki disease (M30.3).

Routine home INR self‑testing more frequently than once weekly for patients beyond the initial titration period is generally not supported by the Medicare Decision Memorandum and this policy. More frequent testing may be clinically justified in the setting of destabilizing events, but such situations typically require direct physician evaluation rather than routine escalation of home testing frequency.

Definitions

inv-22: International Normalized Ratio (INR) definition

DefinitionInternational Normalized Ratio (INR) — a system established for reporting results of blood coagulation tests; the INR is the ratio of an individual’s prothrombin time compared to the mean prothrombin time for a group of normal individuals.

PurposeUsed to standardize reporting of prothrombin time for monitoring anticoagulation therapy.

Clinical useGoal is to help maintain INR within a therapeutic range for patients on warfarin.

inv-23: Home PT/INR monitoring device definition

DefinitionHome PT/INR monitoring device — portable, battery-operated instrument that quantitatively determines prothrombin time and displays/calculates INR from a finger-stick whole blood sample and stores recent results.

AvailabilityAvailable by prescription for home use under a physician’s supervision; physician responsible for training and ongoing management.

Device capabilitiesDisplays PT and calculated INR; stores approximately 30–60 most recent date/time-stamped test results for trend review.

inv-24: Patient self-management (PSM) definition

DefinitionPatient self-management (PSM) — patients measure INR at home and choose their own warfarin dose within a supervised, criteria-driven program.

Criteria-driven triggersExample triggers used in trials include INR <1.8, INR >4.5, weekly warfarin dose change >1.25 mg, or missing INR/dose.

EffectPSM with predefined criteria can maintain therapeutic control while substantially reducing clinician–patient interactions compared with routine care.

inv-25: Patient self-testing (PST) definition

DefinitionPatient self-testing (PST) — patients measure INR at home but management and dosing decisions remain under routine care by clinicians.

Workflow differenceUnlike PSM, PST does not authorize patients to alter dosing; results are reported to and acted on by the treating clinician.

Training requirementPatients must complete an educational program and demonstrate correct device use prior to home testing.

Background

Home PT/INR devices are portable, battery‑operated instruments that quantitatively determine prothrombin time and calculate the INR from a finger‑stick whole blood sample, displaying and storing recent results for trend review. Typical devices have internal storage capacity for approximately 30–60 most recent test results and are intended for use under physician prescription and supervision to support long‑term warfarin management.

Policy Summary

PayerAetna

PolicyProthrombin Time (INR) Home Testing Devices

Policy CodePolicy 0173

Change TypeNo material changes

Effective DateSep 22, 1997

Next Review DateFeb 8, 2024

Key ActionPrescribe home PT monitor, ensure patient training and document demonstrated correct device use prior to home use.

SourceLink

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