Pathology/Lab Coding Alert

Medicare recently announced that it would begin a national coverage policy for home prothrombin time (PT) testing for patients with mechanical heart valves. This policy enlarges the wide range of conditions that are covered for PT tests, which evaluate a patient's blood-clotting ability.
 
The PT test can be used in several settings such as laboratories, physician offices, and homes. Several coverage issues affect reimbursement for this test, including where and how the sample is taken and evaluated, how frequently the test is given, and who oversees the procedure. Appropriate diagnosis coding to establish medical necessity is also crucial for payment. Related coagulation tests might also be ordered, and these should be reported separately.

Coagulation is caused by many reactions involving various factors in the blood. Two converging pathways can result in clot formation: the extrinsic pathway, which is initiated by tissue damage and assessed using PT (85610, prothrombin time), and the intrinsic pathway, which is assessed using PTT (CPT 85730 , thromboplastin time, partial [PTT]; plasma or whole blood). These two tests are commonly used to determine the efficacy of blood-thinning medications based on how long it takes the blood to clot.  
 
"PT is often used to assess the drug warfarin (Coumadin). PTT is frequently used to assess the drug heparin," says Barb Miller, MT (ASCP) SH, clinical lab specialist with Nebraska Health System in Omaha. The PT test results are expressed in seconds and/or as an international normalized ratio (INR). Because commercial thromboplastin reagents used in the laboratory PT test have different potencies, the INR reporting method was developed. The INR is the PT ratio that would result if the World Health Organization reference thromboplastin were used in performing the test. Because INR is a calculation, it is not paid in addition to the PT, but is part of the service described by 85610.
 
In addition to the traditional laboratory methods, PT testing is available through the use of several simplified, automated devices. These PT systems are becoming more common for point-of-care testing. They generally involve direct blood collection through a finger stick into a cuvette containing premeasured reagents. The determination of PT seconds and INR is automatically calculated and recorded in the instrument.
 
Aside from monitoring anticoagulation therapy, other related laboratory tests are used for diagnostic investigations of the patient's hemostatic status. For example, abnormal PT and/or PTT tests may indicate that a patient has a deficiency of one or more coagulation factors. Following these test results, a physician may order a diluted PT (85611,  prothrombin time; substitution, plasma fractions, each) or diluted PTT (85732, thromboplastin time, partial [PTT]; substitution, plasma fractions, each). "Essentially, these tests repeat the PT or PTT on a mixture of the patient's plasma and normal plasma, and the results provide a more specific conclusion as to the cause of the abnormal coagulation," Miller says.
 
Other diagnostic coagulation-related tests include 85670 (thrombin time; plasma) and 85675 (thrombin time; titer), used to evaluate circulating anticoagulants or disorders of fibrinogen. Also, 85705 (thromboplastin inhibition; tissue) tests for the presence of lupus inhibitor, which may occur in some patients with lupus erythematosus or other clinical conditions, Miller says.

Blood for the PT test is commonly acquired by venipuncture or fingerstick. "If the blood is drawn at the laboratory, it is separately reportable in many cases," says Peggy Slagle, CPC, billing compliance coordinator at the University of Nebraska Medical Center department of pathology in Omaha. For commercial payers, report blood collection with 36415 (routine venipuncture or finger/heel/ear stick for collection of specimen[s]). For Medicare patients, report HCPCS code G0001 (routine venipuncture for collection of specimen[s]) because 36415 is not on Medicare's laboratory fee schedule. "Notice that if the blood is acquired by fingerstick, the service cannot be reported separately to Medicare because G0001 only describes venipuncture," Slagle says.
 
Monitoring warfarin therapy with periodic PT tests often happens at a physician office lab, or "coumadin clinic," and may involve a brief visit with a nonphysician practitioner such as a nurse. If the nurse's encounter involves more than the blood draw, the service might be reportable with 99211 (office or other outpatient visit for the evaluation and management of an established patient, that may not require the presence of a physician).
 
Although 99211 does not require the history, examination and medical decision-making components of most other E/M codes, it does typically require that five minutes be spent evaluating and managing the patient's condition. This means the nurse must provide and document services such as taking vital signs and discussing the patient's condition to justify this code. If the visit warrants 99211, do not also report the venipuncture service.
 
Medicare requires direct physician supervision of the 99211 "incident to" service for it to be billable. Although the physician does not have to be present in the room, he or she must be on-site and available to direct and assist. Some local Medicare carriers do not reimburse for any E/M services provided by a nurse. Be sure to include documentation of all services provided that represent 99211 because this code is on CMS' watch list due to frequent abuse. 

The PT test may be ordered for many reasons, and several carriers provide lists of payable diagnoses in their local medical review policies (LMRPs). Generally, PT is indicated for signs or symptoms of abnormal bleeding or thrombosis, e.g., capillary hemorrhage (448.9) or thrombophlebitis (451.x). It may also be ordered for genetic or acquired disorders of the extrinsic coagulation pathway such as dysfibrinogenemia (286.3) or vitamin K deficiency (269.0).
 
However, the most common use of the PT test is the ongoing monitoring of patients taking warfarin. "There are many reasons that a patient may be on anticoagulation therapy, but the underlying condition should not be reported as the primary code for the PT test," Slagle says. "If the reason for the repeated PT tests is to monitor the effectiveness of the medication, the primary diagnosis code for the service should be V58.61 (long-term [current] use of anticoagulants)." The underlying reason for the warfarin therapy, such as mechanical heart valve (V43.3), pulmonary embolism (415.1x), atrial fibrillation (427.31) and acute myocardial infarction (410.x), may be reported as  secondary diagnoses. 
 
Many local carriers limit the frequency of PT testing for patients on stable warfarin therapy to once every four to six weeks. However, according to the CMS final decision memorandum for PT testing (available on the Internet at www.hcfa.gov/coverage/8B3-PP.htm), "Recent data demonstrates that this frequency is inadequate for the majority of patients. The general recommendation for warfarin monitoring to be performed once every four to six weeks is not based on pharmacokinetics nor clotting factor half lives but rather on practical constraints of access and labor-intensiveness balanced against complications."

Based on study results, CMS announced in a final decision memorandum dated Sept. 19, 2001, that it will begin national Medicare coverage of home PT testing that enables patients with mechanical heart valves to measure how well their blood is thinned.
 
The new policy addresses only those patients on blood-thinning medication such as warfarin who have mechanical heart valves, because it is universally agreed that these patients must be anticoagulated in a higher range and for life. According to the CMS memorandum, the evidence for a benefit from home PT testing is less clear than for other patients on anticoagulation therapy. Given further data, CMS stated that it would consider expanding coverage for home PT testing for patients with conditions such as atrial fibrillation, cerebrovascular accident or transient ischemic attack.
 
"We believe that the announced national coverage policy is a good first step, although we hold that there is evidence to cover home PT testing for other indications as well," says Mark Weller, legal counsel to an informal coalition called Doctors for Prothrombin Time Self-Testing in Washington, D.C.
 
Prior to this policy, the four Durable Medical Equipment Regional Carriers (DMERCs) have not covered home PT devices, denying claims as not "medically necessary and reasonable." Many local medical review policies LMRPs allow phlebotomists to draw blood at the patient's home every two to six weeks for conveyance to the laboratory for the PT test as part of home healthcare. However, the new policy will allow beneficiaries to perform the test themselves and permit weekly monitoring of the patient's response to blood-thinning medication.
 
Prothrombin time tests (85610) are approved for labs that have waived status under the Clinical Laboratories Improvement Amendments (CLIA). The manufacturer systems approved for CLIA-waived status are Protime Microcoagulation System by International Technidyne Corp., Coaguchek PST by Boehringer Mannheim (the company has since become Roche Diagnostics), AvoSure PT by Avocet Medical Inc., and Rubicon Prothrombin Time Monitoring System by Lifescan, a Johnson and Johnson company. But both Avocet and Roche have withdrawn from the market due to problems with Medicare coverage for the innovative test, Weller says.
 
The FDA has approved these four systems for home use when prescribed by a physician. All these products have as part of their label that the physician is responsible for the selection, training and ongoing management of patients selected for home testing. The PT measured by these devices is granted waived status under CLIA, according to the CMS memorandum, and must be reported as 85610 with modifier -QW (CLIA waived test) appended.