Handheld coagulation monitors: Cost-effective?
Bedside clot testing standardizes results
There are at least two portable finger-stick coagulation testing devices on the market that you should be aware of. CoaguChek, developed by Boehringer Mannheim/Roche in Indianapolis, and the ProTime Microcoagulation System, manufactured by International Technidyne Corp. in Edison, NJ, are now approved by the Food and Drug Administration for use in the cardiac catheterization lab, the ICU/CCU, the surgical suite, or the patient’s home. (See photo, p. 68.)
Heart patients and others who are taking warfarin (Coumadin) prick their fingers to draw blood, then run the samples through a small, handheld electronic device, which displays the results on a screen.
CoaguChek costs about $1,300 for the handheld monitor and $6 to $8 for each test strip. ProTime lists at $2,000, with $10 for the testing reagent, disposable cuvette, quality assurance control component, and incision device.
How many instruments a hospital chooses to use and how many tests it runs would affect total costs, but in general, the cost per test cartridge is significantly higher than that for reagents used to perform a standard plasma prothrombin time (PT) measurement in the lab. This additional cost, however, may be offset by eliminating the need for venous phlebotomy, sample transportation, and plasma processing required for lab methods. Moreover, the portable devices are convenient and are associated with a decreased incidence of hemorrhage and blood transfusion, further reducing their relative cost.
Patients like devices’ convenience
The handheld instruments allow patients to monitor their response to anticoagulant therapy after discharge, at home. Patients like them because their minds are put at ease — they can check at any time to see if their blood thinner is working properly. Before they receive their monitors, patients complete a training program, and users have access to a toll-free telephone support line that addresses technical issues and reimbursement questions.
Blood thinners have a narrow therapeutic range. If the drug level in the blood is too high, the patient can hemorrhage. If it is too low, clots can form and obstruct blood vessels, causing stroke and even death.
Typically, people taking warfarin are given a PT test every one or two months during regular visits to their doctor. With the new home test systems, patients are able to test themselves weekly, or as often as their doctor recommends.
Forty most-recent results stored
The test devices store the 40 most recent results with a date and time stamp, enabling the doctor to review and interpret the results and adjust therapy accordingly. He can program the systems with the appropriate upper and lower blood clotting range for each patient. The screen displays "In Range" if the results are within the limits or "INR [international normalized ratio] High" or "INR Low." If the results are out of range, the patient is instructed to retest him or herself to confirm and then call the doctor immediately.
Robert M. Siegel, MD, an interventional cardiologist, uses one of the fingerstick devices for his patients at Phoenix Memorial Hospital where he is the director of cardiovascular services. He says it competently and consistently compares with the hospital lab tests.
"In one sitting, it tells patients at home what their INRs are," he says. "The most serious complications of bleeding at home are associated with warfarin therapy. And a major inconvenience is having to go to the doctor’s office or the hospital every other day or on a weekly basis for blood coagulation checks. Once the patient gets there, often he has to wait hours to find out what the level was yesterday, not today, because eating broccoli or taking extra aspirin can throw that level off temporarily.
"It’s convenient, yes, but I like it most for compliance and successful therapy," he continues. "Its almost-instant response is a positive experience, and the patient immediately gets his dose changed, if necessary."
Accuracy not a problem
Siegel says he’s never had any trouble with the devices, and the unit checks their accuracy daily. "We have five devices in each clinic and can check one against another," he says.
Patients who stay within therapeutic range have a significant chance to avoid major adverse events, and studies have shown that those who self-test stay within range more than those who must go to a lab for their testing. According to Jack Ansell, MD, professor of medicine at Boston University Medical Center, patient self-testing provides several additional clinical advantages:
• It invests patients in their own care.
• It empowers them to be interested in their care and be as compliant as possible.
• It allows more frequent testing, resulting in improved control.
In addition, a recent study showed that 38 out of 40 patients questioned six months after initiation of self-testing say that self-testing causes less discomfort, less anxiety, and less inconvenience than traditional laboratory visits. One said, "A few weeks ago, my INR reading was unusually high. I was able to spot this immediately, talk with my doctor, and adjust my dosages."
Patients monitored at bedside bleed less
The ProTime test system has been cleared only for use by patients taking warfarin, but researchers recently concluded that CoaguChek is an effective alternative to standard methods of monitoring heparin-induced anticoagulation after thrombolytic therapy.1
Patients monitored by the bedside instrument had significantly less bleeding and needed fewer blood transfusions than their counterparts whose blood samples went to the lab.
One explanation is that the rapid availability of results allows quick titration of the heparin infusion in patients with very high values, thereby limiting their exposure to the hemorrhagic risks associated with aggressive anticoagulation. By eliminating the need for venous phlebotomy, specimen transport to a central laboratory, data entry into hospital information systems, and complicated plasma processing, bedside monitors can dramatically reduce the turnaround time for blood samples.
Finding portables comparable to lab methods
Those investigators saw no significant difference in stroke rates, development of congestive heart failure, or survival rates. Their chief finding was that the use of bedside monitors was associated with no detectable increase in overall adverse clinical events compared with standard laboratory methods.
Another advantage of using the handheld devices for either warfarin or heparin therapy is that the portable systems compensate for the varying technical methods among different hospitals and labs. Reagents respond differently, and instrumentation, phlebotomy methods, and delays in testing samples after collection introduce further variability to test results. ProTime and CoaguChek results are standardized.
Reference
1. Zabel KM, Granger CB, Becker RC. Use of bedside activated partial thromboplastin time monitor to adjust heparin dosing after thrombolysis for acute myocardial infarction. Am Heart J 1998; 136:868-876.
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