In response to the letter to the editor from Marilyn Kenyon, MT (ASCP) (March 2011), regarding the article on home INR monitoring (January 2011), I would like to comment on the following aspects of INR monitoring.
I am at a loss to understand the statement, “On the patients who request a fingerstick INR, we perform three fingersticks, and on the fourth INR we perform a venipuncture.” Perhaps this was the procedure when they were doing their correlation study? Second, what is the correlation of the laboratory at St. Joseph’s Hospital with other hospitals in the area, in the state, and in the country? There are literally dozens of reagent/instrument permutations, and it is well known there is poor correlation between INRs done on different instruments and with different reagents. Thus, for patients who may obtain an INR for warfarin monitoring at different laboratories, as many do over time, how assured can one be that there is correlation between results?
With regard to ease of performing a fingerstick INR, I believe the THINRS study shows very well that the overwhelming majority of patients (80 percent in this study) can perform an adequate INR. Whether the blood glucose is high or low has little to do with the ability to perform a fingerstick blood test, either blood glucose or INR, though the symptoms from an excessively high or low glucose may stimulate a patient to test his or her glucose. This would not be the case with warfarin (unless there was obvious bleeding), but the INR does not fluctuate as rapidly as the blood glucose, and recommendations to check an INR weekly or every other week would be adequate to catch serious out-of-range levels. Further in this regard, I suspect that a serious out-of-range glucose (which can change within hours) is potentially more life-threatening than a slowly changing INR (over days or weeks).
Lastly, there are anecdotes about malfunctioning meters, strips, and so on. However, how many times does an anticoagulation clinic provider get an erroneous INR result from the laboratory? Anyone working in the field knows this is not a rare occurrence (regardless of whether it is a preanalytic, analytic, or postanalytic error).
In closing, patient self-testing with point-of-care INR monitors has been shown over and over to be safe and effective. Whether it is better than well-managed warfarin therapy in an anticoagulation clinic is still debatable, but it is certainly not worse.
Jack Ansell, MD
Professor of Medicine
New York University
School of Medicine
Chairman, Department of Medicine Lenox Hill Hospital
New York, NY
Marilyn Kenyon, MT(ASCP), wrote she disagreed with me and Jack Ansell, MD, concerning our analogy “that if diabetes patients can use a glucose meter, then warfarin patients should have no problems.” She says: “Diabetes patients can usually tell if their glucose is high or low; it is difficult for warfarin patients to tell if their INR is therapeutic. The consequences of a low or high INR can be life-threatening.”
Indeed, the potential adverse events of a non-therapeutic INR can be life-threatening, but this is precisely why INR self-testing should be used. Neither patients nor physicians know what the coagulation status of the patient is without doing a blood test. With patient self-testing, this information is available virtually on demand, regardless of where the patient is or when the INR is needed. In the usual care setting, patients are tested every four to six weeks, and only if/when they experience a visible problem, such as unusual bleeding or bruising, will they seek help. Under-anticoagulated patients may have no indication they are subtherapeutic until it is perhaps too late.
I want to reiterate that patient self-testing is for “properly selected and suitably trained” patients, as the January 2011 article made clear. The patients Kenyon describes in her letter who use outdated strips or dose themselves are not the appropriate patient self-testing candidates.
Circulating tumor cells
VP, Market Development
The article “Sizing up a role for circulating tumor cells” (March 2011) is of interest but did not acknowledge the many pioneer cytopathologists who previously contributed expertise and research to this subject. This area of cytopathology is not new. Leopold Koss, MD, an attending pathologist at Memorial Sloan-Kettering Cancer Center, at the time of writing the first edition of his textbook, Diagnostic Cytology and Its Histopathologic Bases, 1961, devotes two pages to this subject and notes a reference back to 1869. A number of expert cytopathologists researched this area in the 1950s and ’60s, including McGrew, Christopherson, and von Hamm, to name but a few. Also described in detail was a curious phenomenon dubbed malignancy-associated changes, peculiar nuclear features in otherwise essentially normal-appearing epithelial and/or blood cells. A notable researcher in this area was Herbert Nieburgs who published his findings as part of a monograph, Diagnostic Cell Pathology in Tissue and Smears, in 1967. In the mid ’60s parts of the annual meetings of the American Society of Cytology were devoted to the presentation of papers on the subject of circulating cancer cells and malignancy-associated changes. Dr. Koss expanded his discussion of circulating tumor cells in each subsequent edition of his text of diagnostic cytology; in the most recent, fifth, edition the discussion encompasses an entire chapter of 22 pages.
The subject of circulating tumor cells is interesting and exciting, furthered today by more sophisticated techniques of molecular pathology and cell sorting and detection instruments that grew out of many years of research devoted to automation of cervical vaginal cytology. It is important to remember those who went before.
William J. Frable, MD
Goodbye, Dale Dauten
Professor of Pathology
Virginia Commonwealth University
I was sorry to learn that soon I will no longer be seeing and reading Dale Dauten’s column in CAP TODAY. If I read nothing else in CAP TODAY, I never failed to read Dauten’s column. I feel like I am losing a good friend with whom I visit every month.
Too often as pathologists we focus on technical and business matters. We rarely focus on our interactive and management skills and how to be a better person. Much of this is common sense yet not so commonly mastered. No matter how much technical information we possess, no matter how many procedures we master, it is our ability to master managing and leading that will make it or break it for us.
Dale, I will miss you. Best wishes to you in whatever you plan next.
Roslyn Yomtovian, MD
Department of Pathology
Case Western Reserve University School of Medicine
Department of Pathology
and Laboratory Medicine
Louis Stokes VA Medical Center