Pathology/Lab Coding Alert

Don’t miss management pay.

With the need to oversee coagulation in approximately 20 million people taking warfarin (trade name Coumadin) in the U.S. each year, your lab may encounter lots of claims for prothrombin time (PT)/international normalized ratio (INR) lab tests and other monitoring services.

Medicare sets the bar for all this PT/INR management with two National Coverage Determinations (NCDs) and a few HCPCS Level II “G” codes that you need to know. Let us sort out the rules and codes to make sure you get your claims right.

PT Lab Test

Medicare’s NCD for PT (190.17, available at www.cms.gov/medicare-coverage-database/indexes/ncd-alphabetical-index.aspx) outlines when and how your lab can get paid for performing the PT lab test.

Relation to INR: The PT test involves mixing a thromboplastin reagent with patient blood and determining clotting time in seconds. To account for variation in reagent potencies, labs typically also report the test result as an INR ratio – normalizing what the PT test result would be if the lab had used the World Health Organization (WHO) reference thromboplastin to perform the test. The PT lab test code is 85610 (Prothrombin time). Because INR is a calculation, a PT test includes results reported as both seconds and INR, and you will not receive additional pay for reporting the INR.

Warfarin: NCD 190.17 states that “The PT/INR is most commonly used to measure the effect of warfarin and regulate its dosing.” Warfarin works by blocking vitamin K’s effect on the liver’s production of extrinsic-pathway coagulation factors, and thus, slows the blood clotting time. The goal of warfarin therapy is to slow clotting time to a target range to decrease the risk of adverse events such as stroke, but still allow safe blood clotting. The PT/INR measurement helps physicians adjust warfarin dosage.

Diagnosis: If monitoring warfarin therapy is the reason for the PT test, you should report Z79.01 (Long term (current) use of anticoagulants) as the primary diagnosis, according to Peggy Slagle, CPC, coding and compliance manager for Regional Pathology Services at the University of Nebraska Medical Center in Omaha. You should also report a secondary diagnosis for the underlying reason for the warfarin therapy.

Home INR Monitoring

For certain patients on warfarin, Medicare has approved a home-monitoring system based on evidence that patient self-testing may improve the time in therapeutic rate (TTR). The TTR reflects the amount of time that the patient’s INR is in the target range. A higher TTR relates to better clinical outcomes with fewer adverse bleeding or thrombosis events.

Coverage: The NCD for home PT/INR monitoring for anticoagulation management (190.11) indicates coverage when prescribed by a physician for patients taking warfarin who have at least one of the following conditions:

• mechanical heart valve
• atrial fibrillation
• venous thromboembolism

The patients must also meet the following criteria before Medicare will cover the home monitoring:

• The patient must have been anticoagulated for at least »three months prior to use of the home INR device
• The patient must undergo a face-to-face educational »program on anticoagulation management and must have demonstrated the correct use of the device prior to its use in the home
• The patient continues to correctly use the device in »the context of the management of the anticoagulation therapy following the initiation of home monitoring
• Self-testing with the device should not occur more »frequently than once a week.

Crucial: The two different NCDs for the lab PT test and home PT/INR monitoring don’t overlap, and the patient may receive both services. The home monitoring NCD states “This national coverage determination (NCD) is distinct from, and makes no changes to, the PT clinical laboratory NCD at section 190.17.”

Also note: The payable diagnoses are distinct for the lab and home PT/INR testing (you can find the list of ICD-10 codes in the NCDs).

Warfarin Monitoring Oversight

In addition to the 85610 lab test code, you can report a separate service if your pathologist provides interpretation and oversight for warfarin dosage.

In many cases, you should use 93793 (Anticoagulant management for a patient taking warfarin, must include review and interpretation of a new home, office, or lab international normalized ratio (INR) test result, patient instructions, dosage adjustment (as needed), and scheduling of additional test(s), when performed) for managing patients taking warfarin, according to Christina Neighbors, MA, CPC, CCC, coding quality auditor for Conifer Health Solutions, Coding Quality & Education Department.

Code 93793 includes the review and interpretation of a new lab test done in a home, the office, or the lab. This code’s relative value unit (RVU) is for the work done to interpret the lab results, make a dosing adjustment if needed, and scheduling additional tests when and if needed. A dosage change is not required to report 93793.

Limit: You should not report 93793 more than once per day regardless of the number of tests the provider reviews, says Neighbors.

Initiation: For the work of a physician or other qualified healthcare provider to initiate home INR monitoring, CPT^® provides 93792 (Patient/caregiver training for initiation of home international normalized ratio (INR) monitoring under the direction of a physician or other qualified health care professional, 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).

For Medicare: When your physician or other qualified healthcare provider establishes and monitors home PT/INR monitoring for a Medicare patient, you should instead turn to one of the following codes:

• G0248 (Demonstration, prior to initiation of home INR monitoring, for patient with either mechanical heart valve(s), chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria, under the direction of a physician; 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’s ability to perform testing and report results)
• G0249 (Provision of test materials and equipment for home INR monitoring of patient with either mechanical heart valve(s), chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria; includes: provision of materials for use in the home and reporting of test results to physician; testing not occurring more frequently than once a week; testing materials, billing units of service include 4 tests)
• G0250 (Physician review, interpretation, and patient management of home INR testing for patient with either mechanical heart valve(s), chronic atrial fibrillation, or venous thromboembolism who meets Medicare coverage criteria; testing not occurring more frequently than once a week; billing units of service include 4 tests).

Tip: To report G0250, there must be record of at least four individual results and/or interpretations and at least four weeks (28 days) between claims submission.

Caution: You should not report the “G” codes with the CPT^® codes for similar services. The Correct Coding Initiative (CCI) edits bundle G0248 as a column 2 code for 93792, and G0250 as a column 2 code for 93793. CCI lists these edit pairs with a modifier-indicator of “0,” meaning that you cannot override the edit pair under any circumstances.