There have been many articles written lately about the use of electronic medical records (EMRs) in the hospitals, in the emergency rooms, and in doctors' offices. These articles have appeared in newspapers, in medical journals, and in statements from the government, from medical societies, and most recently from the office of the Medicare Inspector General. As one who used to always use pen and paper and now still uses them in my office but not in the hospital, I would like to offer my perspective, which is in addition to my previous blog on this subject.
Firstly, we have the Scylla of insurance companies saying that if you didn't write it down you didn't do it and can't bill for it, or the Charybdis of the same companies saying that just because you wrote it down it doesn't mean that you actually did it. In either case, you cannot prove a negative, and lack of evidence is not equivalent to evidence of a lack, as any first-year logic student could tell you. Doctors used to be told that they should document what they did very carefully in the chart because (a) other doctors would depend upon their notes, and (b) careful documentation was the best defense against malpractice. Now the same doctors are told that if they do not document their actions carefully, they cannot bill for what they did, so the incentive has changed from good (for the patient) medical practice to good (for the doctor and hospital) financial practice.
Not to be a complete Devil's advocate, but we doctors are pretty savvy, and we have been gaming the system for our patients' benefit for years: If the insurance company will not pay for a PPI drug unless the patient has GERD and not just a stomach ulcer, then presto---all of our ulcer patients for whom we wish to prescribe a PPI have GERD. Similarly, if I think a patient is anemic, Medicare will not pay for a CBC blood test to look for anemia, because "rule out" or "I think that" is not a disease, but Medicare will pay for a CBC if the patient has fatigue (code 780.79) and every patient has been tired at least once since birth, so I can code "fatigue" with complete honesty, since no time frame is asked for in the diagnostic box. I even know doctors (not me) who code 799.99, "unknown disease", telling themselves that every patient has at least one unknown disease, which is ultimately known only to the pathologist. You note that in each of the above cases, our experience tells us that a patient needs a certain drug or test, and we have to adjust our codes and words so that it is paid for. One might argue that it is the patient's responsibility to pay, but if a doctor knows that then the test will not be taken or the drug not obtained, I feel that we are morally obliged to act in the patient's best interest to ensure the best possible result, because our implied contract is with the patient to see that he/she gets the best care possible.
So the medical record now has a dual purpose: to document what the doctor sees and thinks as well as to record the results of tests, and to provide evidence for the doctor's and hospital's bill. Usually these two requirements are not at cross-purposes, but they do act to increase the amount of time a doctor spends recording data. Trivially, a doctor cannot write "cardiac exam unchanged" if he wishes to get credit for examining the heart, but he must repeat his examination and notation of the PMI, murmurs, gallops, splits, clicks, etc. Of course with the right computer template he can just cut and paste to achieve this result, but this does take time, and time is a doctor's least fungible resource. There even are computer systems where if the doctor clicks "normal lungs" the template spits out words like "clear to percussion and auscultation, no vocal fremitus, no egophony, no post-tussive rales, diaphragms move well and equally", etc. I want to emphasize that the doctor did perform the complete pulmonary exam, but the use of the automatic printout saves him time in writing it all out. And the doctor is no more likely to click on the link without doing the actual exam than he would be to write "normal lungs" without doing the exam.
Now what are the putative and actual results of electronic medical records aka computer printouts? In theory, there should be fewer errors and patients' care should improve, but I know of no studies demonstrating a decrease in morbidity and mortality. And the Johns Hopkins pediatric hospital where pharmacy errors were noted pre-computer orders was shown to have an increase in medication errors after the introduction of computer-only orders. At my own institution, the system was down for 36 hours due to some glitch (gremlins anyone?) and the residents were quite helpless. I do know that the housestaff have become technocrats: When I asked one resident what a patient's hematocrit was, I was told that it wasn't in the computer yet, and when I suggested calling the hematology lab for the result, I was met with an incredulous stare, as if it never occurred to the resident that somewhere a human had to generate the test result before it was logged into the computer.
Then we have the question of the security of medical records. We are always reading about CD's being left in taxicabs with thousands of patients' records, or a computer billing service accidentally releasing patients' information. I doubt that any of you would trust the security of a computer to keep secret the fact that you are an adulterous, bisexual, cocaine-using, HIV-positive patient with a gambling and an alcohol problem. All of us have patients that ask us not to write down certain embarrassing facts, but if the ER doctor thinks that the electronic record is complete, they will never call the family doctor to find out those key additional facts. My main responsibility is always to the patient, and I keep a problem list of embarrassing facts separate from the office chart, with the understanding that I will forward a complete problem list to any doctor to whom I refer the patient. I also should mention that when a patient comes to the ER, where one would think an accurate record would be of vital importance, his/her life is generally saved without reference to any written past medical history. The complete medical history is of most value to the next office doctor, who needs the total story to be digested at leisure.
One last concern: I know that I have trouble finding a place to view my VCR tapes, I've given up on my 8-track musical tapes, and my new car won't accept cassettes, but only plays CD's. What happens when an old computer record cannot be accessed by the new computer system? Yet I have pen and ink notes in the chart of 80 year old patients that are perfectly legible 50 years after they were written by my predecessor. Does anyone have a timeless electronic version of the Rosetta Stone?
Thursday, September 27, 2012
Tuesday, September 18, 2012
Fingerprints and Fingerprint Identification
I had been reading articles about how "incontrovertible" eyewitness identification and/or fingerprint identification led to the conviction of indicted persons, only to have the conviction legally overturned when DNA evidence showed scientifically that the person so identified was not the person who committed the crime. I began to investigate the use of fingerprints, looking for the basic science involved in saying that a fingerprint found at the scene of a crime matched that of a suspect, and I was surprised and shocked at what passed for "scientific evidence". As you will see below, any fingerprint identification is purely a judgment call, and the only basic science is that no two individuals have been shown to have the same ten fingerprints, much as no two individuals have exactly the same face (and both statements do apply to identical twins). The only distinction between the two is that some people are born without fingerprints and never develop them, while everyone has a face.
The fingerprint found at the scene of a crime is called a latent fingerprint. It typically is only a portion of a fingerprint, and is usually smudged and distorted. The job of the fingerprint expert (with or without the help of a computer) is to make the final decision as to whether or not this partial fingerprint can be reliably and validly said to have come from a person whose fingerprints are on file. The decision is a judgment call, based on the expert's experience and visual intuition, and the fact that no two people have the same set of fingerprints is not the same as saying that no two people could leave the same latent fingerprint.
The examiner looks for points of agreement, called Galton points, between the partial ridges of the latent fingerprint and the fingerprints on file, and no one knows the error rate for fingerprint identification. How many points of agreement are needed to call it a match (assuming the determination of a point of agreement is made without error)? New York, California, and London all have different numbers. In Italy, 16 points of agreement are needed to declare a match, while France and Australia require 12, and our own FBI has no minimum number of matching points to declare an ID. In America the number of points of agreement required varies from state to state, and even within a state.
No pair of latent and rolled (recorded) fingerprints are ever 100% identical, so the question is: how much agreement is enough? There is no available evidence to answer the question as to how much correspondence between two fingerprints is needed to say that they were made by the same person. The examiner decides how much is enough, and there are no universally agreed upon standards as to what constitutes a match, nor are there any published studies of the ability of experts to match one fingerprint to another.
I could find mention of only two tests given nationwide to fingerprint experts. In one case, the FBI sent two fingerprints from a robbery (where the identity was known) to 50 state fingerprint laboratories, and 10 failed to identify them correctly. In 1995 the Collaborative Testing Service, in a test okayed by the International Association for Identification sent 156 experts 4 suspect cards with all 10 prints along with 7 latents for identification. Only 66 of the 156 correctly identified all 7 latents, a success rate of less than 50%, and there were 44 incorrect identifications.
Lest my readers think that this is all theoretical, and I am exaggerating the room for error, let me close by citing two internationally known cases of fingerprint error, one by the FBI and one by Scotland Yard, which led to the arrest of innocent people (one of them a policewoman), and then payment of monetary damages ($2M to the American) to both individuals because of the harm done to them.
In 1998 the fingerprint of Policewoman McKie was found in the room of a murdered man in Scotland. The police had arrested a man for the murder, and asked her to account for the presence of her fingerprint. She swore that she had never been in the room, but even her father, a former policeman, believed the evidence. On the basis of the one fingerprint, she was indicted and put on trial for perjury. Her expert (who was later hounded out of his job at Scotland Yard and shunned by his co-workers) testified that not only wasn't it her fingerprint, but they police had claimed that the partial had matched her left thumb, while he clearly demonstrated that the latent was of a right forefinger. She was acquitted but left the force.
In 2004 a bombing in Madrid, Spain killed over 100 people. The Spaniards found one latent print, and circulated it around the world. The FBI claimed that it was the print of an Arab in the U.S. named Mayfield, and arrested him as a material witness. They said they had 15 points of agreement, and that this was verified by three different FBI fingerprint experts. The Spanish police said that there were only 7 points of agreement, and that he couldn't have been the man (plus he had never left the country), and that the FBI had misidentified him. The Spaniards later found a man whose fingerprint they said was a match, and they then connected him with the presence of explosives, arrested him and convicted him.
Until I began my reading, I did not realize how subjective the "science" of fingerprint-matching really was. There are no hard and fast standards, and the match is really in the eye of the beholder, much as is facial identification. The fact that fingerprints are almost certainly unique does not in and of itself make fingerprint ID valid and correct, any more than the uniqueness of our face makes witness ID 100% accurate.
The fingerprint found at the scene of a crime is called a latent fingerprint. It typically is only a portion of a fingerprint, and is usually smudged and distorted. The job of the fingerprint expert (with or without the help of a computer) is to make the final decision as to whether or not this partial fingerprint can be reliably and validly said to have come from a person whose fingerprints are on file. The decision is a judgment call, based on the expert's experience and visual intuition, and the fact that no two people have the same set of fingerprints is not the same as saying that no two people could leave the same latent fingerprint.
The examiner looks for points of agreement, called Galton points, between the partial ridges of the latent fingerprint and the fingerprints on file, and no one knows the error rate for fingerprint identification. How many points of agreement are needed to call it a match (assuming the determination of a point of agreement is made without error)? New York, California, and London all have different numbers. In Italy, 16 points of agreement are needed to declare a match, while France and Australia require 12, and our own FBI has no minimum number of matching points to declare an ID. In America the number of points of agreement required varies from state to state, and even within a state.
No pair of latent and rolled (recorded) fingerprints are ever 100% identical, so the question is: how much agreement is enough? There is no available evidence to answer the question as to how much correspondence between two fingerprints is needed to say that they were made by the same person. The examiner decides how much is enough, and there are no universally agreed upon standards as to what constitutes a match, nor are there any published studies of the ability of experts to match one fingerprint to another.
I could find mention of only two tests given nationwide to fingerprint experts. In one case, the FBI sent two fingerprints from a robbery (where the identity was known) to 50 state fingerprint laboratories, and 10 failed to identify them correctly. In 1995 the Collaborative Testing Service, in a test okayed by the International Association for Identification sent 156 experts 4 suspect cards with all 10 prints along with 7 latents for identification. Only 66 of the 156 correctly identified all 7 latents, a success rate of less than 50%, and there were 44 incorrect identifications.
Lest my readers think that this is all theoretical, and I am exaggerating the room for error, let me close by citing two internationally known cases of fingerprint error, one by the FBI and one by Scotland Yard, which led to the arrest of innocent people (one of them a policewoman), and then payment of monetary damages ($2M to the American) to both individuals because of the harm done to them.
In 1998 the fingerprint of Policewoman McKie was found in the room of a murdered man in Scotland. The police had arrested a man for the murder, and asked her to account for the presence of her fingerprint. She swore that she had never been in the room, but even her father, a former policeman, believed the evidence. On the basis of the one fingerprint, she was indicted and put on trial for perjury. Her expert (who was later hounded out of his job at Scotland Yard and shunned by his co-workers) testified that not only wasn't it her fingerprint, but they police had claimed that the partial had matched her left thumb, while he clearly demonstrated that the latent was of a right forefinger. She was acquitted but left the force.
In 2004 a bombing in Madrid, Spain killed over 100 people. The Spaniards found one latent print, and circulated it around the world. The FBI claimed that it was the print of an Arab in the U.S. named Mayfield, and arrested him as a material witness. They said they had 15 points of agreement, and that this was verified by three different FBI fingerprint experts. The Spanish police said that there were only 7 points of agreement, and that he couldn't have been the man (plus he had never left the country), and that the FBI had misidentified him. The Spaniards later found a man whose fingerprint they said was a match, and they then connected him with the presence of explosives, arrested him and convicted him.
Until I began my reading, I did not realize how subjective the "science" of fingerprint-matching really was. There are no hard and fast standards, and the match is really in the eye of the beholder, much as is facial identification. The fact that fingerprints are almost certainly unique does not in and of itself make fingerprint ID valid and correct, any more than the uniqueness of our face makes witness ID 100% accurate.
Sunday, September 9, 2012
Untreated Hypertension (High Blood Pressure)
One of the latest pieces to hit the news is that there are 32 million patients with hypertension (high blood pressure), 30 million of whom have medical insurance, who are not properly treated. By this the report means that their blood pressure is still at 140/90 or higher after being seen by a doctor (how many visits is unclear). Then the report calls for a massive effort to treat 10 million of these people to goal blood pressure in the next five or ten years.
The problem with the emphasis on this statistic is that it completely ignores the patients, and focuses on the health profession instead. This is not dissimilar to the problem with getting patients to stop smoking, to exercise more, and to lose weight. The patients know what has to be done, but choose not to do it.
The treatment models for smoking and obesity do not work for hypertension. Firstly, there is no moral obloquy in having high blood pressure, because the general public has no way of knowing that you are an untreated hypertensive. Secondly, until the first stroke, the patient feels no ill effects from the high blood pressure, much in the same way that diabetics feel no effect that they can ascribe to a high blood sugar. Thirdly, because of #2, it is difficult to convince most patients that they have a medical problem that requires pharmacological and/or lifestyle intervention.
The easiest person to fool is yourself, as Richard Feynman famously remarked. When I encourage my hypertensive patients to take their blood pressure at home, close questioning reveals that most of them duplicate the behavior of my diabetics who measure their blood sugar by fingerstick at home. Both groups usually repeat the measurement several times until they get a number that satisfies them and then they record that number. With diabetics, I can use the glycohemoglobin to demonstrate this, but with hypertensives there is no way to verify their home numbers.
What I am saying is that there has to be a massive propaganda effort to convince patients that untreated hypertension is a time bomb waiting to explode in their brain, to discuss the debilitating effects of a stroke, and to quote from the studies that have demonstrated that lowering high blood pressure significantly reduces the risk of a stroke. We still would then be left with a subset of patient who insist that lifestyle modification alone can control their blood pressure, while I try to explain that blood pressure, blood sugar and blood cholesterol all usually increase with age and that once they have hypertension the number rarely decreases of its own accord. In other words, the problem is not a lack of information transfer from the medical staff to the patient, but a lack of belief on the part of the patient that intervention is necessary.
The problem with the emphasis on this statistic is that it completely ignores the patients, and focuses on the health profession instead. This is not dissimilar to the problem with getting patients to stop smoking, to exercise more, and to lose weight. The patients know what has to be done, but choose not to do it.
The treatment models for smoking and obesity do not work for hypertension. Firstly, there is no moral obloquy in having high blood pressure, because the general public has no way of knowing that you are an untreated hypertensive. Secondly, until the first stroke, the patient feels no ill effects from the high blood pressure, much in the same way that diabetics feel no effect that they can ascribe to a high blood sugar. Thirdly, because of #2, it is difficult to convince most patients that they have a medical problem that requires pharmacological and/or lifestyle intervention.
The easiest person to fool is yourself, as Richard Feynman famously remarked. When I encourage my hypertensive patients to take their blood pressure at home, close questioning reveals that most of them duplicate the behavior of my diabetics who measure their blood sugar by fingerstick at home. Both groups usually repeat the measurement several times until they get a number that satisfies them and then they record that number. With diabetics, I can use the glycohemoglobin to demonstrate this, but with hypertensives there is no way to verify their home numbers.
What I am saying is that there has to be a massive propaganda effort to convince patients that untreated hypertension is a time bomb waiting to explode in their brain, to discuss the debilitating effects of a stroke, and to quote from the studies that have demonstrated that lowering high blood pressure significantly reduces the risk of a stroke. We still would then be left with a subset of patient who insist that lifestyle modification alone can control their blood pressure, while I try to explain that blood pressure, blood sugar and blood cholesterol all usually increase with age and that once they have hypertension the number rarely decreases of its own accord. In other words, the problem is not a lack of information transfer from the medical staff to the patient, but a lack of belief on the part of the patient that intervention is necessary.
Thursday, September 6, 2012
The Art (i.e. Human Side) of Medicine
It has often been said that medicine is an art in addition to being a science, in that it is based, in part, on human-to-human interaction, with all the dynamics and pitfalls inherent in this process. There are qualities that make a warm, interactive, "human" doctor, and we try to instill them in our medical students and residents both by lecture and by example. Below I will try to list some of the qualities and actions of which we try to make the students aware; some are actions to imitate and assimilate and some to avoid. This list is by no means complete, and the order in which it is presented does not correspond to the relative importance of the topics.
Try to maintain eye contact. Patients complain that many of their doctors, especially referred-to specialists, spend most of their time entering data and looking at their computer screens.
Always touch the patient at every visit, even if it is only to feel the pulse.
Always sit down when you talk to the patient, so the patient doesn't feel hurried.
Remember that ALL patients are anxious when in the presence of a doctor, and their anxiety increases sharply as the physical exam commences.
If the patient has a chronic disease, there is probably also an element of depression.
One of the most challenging problems in medicine is to help a patient with irritable bowel syndrome to realize that the symptoms and complaints are functional in nature.
If the patient comes in with a cough, and you diagnose diabetes, the patient will feel untreated because you didn't "solve" the presenting problem.
Always ask the patient what he/she thinks is wrong.
Remember that the patient does not see and interact with you per se, but with Doctor You, so you are being viewed through colored glasses.
Try to understand the patient's mental model of disease and acceptable treatment, or else your advice will not be fully followed, and possibly not followed at all.
Roughly speaking, 25% of patients never fill the doctor's prescription, of those who fill it 25% never take it at all, and of those who take it only 25% take it as frequently as prescribed.
Always ask the patient which medicines their friends and relatives have given them to try.
All patients have unspoken assumptions about their doctors, based in part on their prior interaction with authority figures as well as with adults of the doctor's age and sex, and they will ascribe qualities to you that you do not possess.
Please remember that no matter how intelligent your patient is, almost no patient has an accurate idea of how the body works, and is woefully ignorant of basic human physiology. (If I had my way, a year course of human physiology would be mandatory in every high school in the United States----I think that this would produce healthier patients.)
Part of a doctor's responsibility is to define "normalcy" for the patient. Remember the old saying that an alcoholic is a patient who drinks more than his/her doctor does.
Patients will emphasize and de-emphasize if not totally omit or forget parts of their medical history, in part due to the stress of seeing a doctor, so I find it useful to repeat some questions during the patient's examination. In the hospital it is very common that the history I obtain from the patient on my morning rounds is different from the history the intern recorded in the medical chart the previous evening.
In general, only a fraction of what you tell the patient will be remembered, and only some of your advice will be acted on.
If the patient has a chronic illness, then the spouse is also under stress, and this stress is often ignored or not thought about by the patient's physician.
I often call the patient the next day to see if further thoughts have occurred to the patient, or if any other questions have occurred to him/her, as well as just to "touch base", and I invite the patient to call me if new symptoms or questions occur.
All my patients were told that if they called my office with a problem before 10 AM then I would fit them in that same day.
If I had important instructions for the patient, I would type them out on carbonless carbon paper, with the note mailed to the patient and the copy placed in the chart, so that we each knew what the plan was.
Try to maintain eye contact. Patients complain that many of their doctors, especially referred-to specialists, spend most of their time entering data and looking at their computer screens.
Always touch the patient at every visit, even if it is only to feel the pulse.
Always sit down when you talk to the patient, so the patient doesn't feel hurried.
Remember that ALL patients are anxious when in the presence of a doctor, and their anxiety increases sharply as the physical exam commences.
If the patient has a chronic disease, there is probably also an element of depression.
One of the most challenging problems in medicine is to help a patient with irritable bowel syndrome to realize that the symptoms and complaints are functional in nature.
If the patient comes in with a cough, and you diagnose diabetes, the patient will feel untreated because you didn't "solve" the presenting problem.
Always ask the patient what he/she thinks is wrong.
Remember that the patient does not see and interact with you per se, but with Doctor You, so you are being viewed through colored glasses.
Try to understand the patient's mental model of disease and acceptable treatment, or else your advice will not be fully followed, and possibly not followed at all.
Roughly speaking, 25% of patients never fill the doctor's prescription, of those who fill it 25% never take it at all, and of those who take it only 25% take it as frequently as prescribed.
Always ask the patient which medicines their friends and relatives have given them to try.
All patients have unspoken assumptions about their doctors, based in part on their prior interaction with authority figures as well as with adults of the doctor's age and sex, and they will ascribe qualities to you that you do not possess.
Please remember that no matter how intelligent your patient is, almost no patient has an accurate idea of how the body works, and is woefully ignorant of basic human physiology. (If I had my way, a year course of human physiology would be mandatory in every high school in the United States----I think that this would produce healthier patients.)
Part of a doctor's responsibility is to define "normalcy" for the patient. Remember the old saying that an alcoholic is a patient who drinks more than his/her doctor does.
Patients will emphasize and de-emphasize if not totally omit or forget parts of their medical history, in part due to the stress of seeing a doctor, so I find it useful to repeat some questions during the patient's examination. In the hospital it is very common that the history I obtain from the patient on my morning rounds is different from the history the intern recorded in the medical chart the previous evening.
In general, only a fraction of what you tell the patient will be remembered, and only some of your advice will be acted on.
If the patient has a chronic illness, then the spouse is also under stress, and this stress is often ignored or not thought about by the patient's physician.
I often call the patient the next day to see if further thoughts have occurred to the patient, or if any other questions have occurred to him/her, as well as just to "touch base", and I invite the patient to call me if new symptoms or questions occur.
All my patients were told that if they called my office with a problem before 10 AM then I would fit them in that same day.
If I had important instructions for the patient, I would type them out on carbonless carbon paper, with the note mailed to the patient and the copy placed in the chart, so that we each knew what the plan was.
Wednesday, September 5, 2012
Swine Flu Variant Outbreak
The flu vaccine immunizes you against the swine flu, H3N2, but there has been a recent outbreak of a variant of this virus, called H3N2v, which variant has extra genetic material. It is associated with being in close proximity to live pigs, and so far there has been one death. It probably behooves us to get the flu shot early this year, and to avoid live pigs if you have any immune deficiencies or suffer from a chronic disease. The link to the article posted by the cdc is http://www.cdc.gov/flu/swineflu/h3n2v-outbreak.htm.
Tuesday, August 28, 2012
Are Medical Tests Overused?
There have recently been a slew of articles about the overuse of medical testing. Special attention has been directed towards radiological studies (including in-office ultrasound) and OTC testing kits sold to consumers. However, none of these articles takes the patients' views and wishes into account.
One philosophical question arises when the patient asks for a test, blood or radiological, which the physician knows will be negative. Is there anything ethically wrong in ordering this test to give the patient peace of mind, assuming that the physician explains the probability of a false negative test and the problems and possible morbidity that can follow from acting on a false positive test? I think not. In some cases a negative test (e.g. a cardiac stress test in a patient suffering chest pain from a panic attack) will permit the physician to direct the patient's attention to the underlying problem. This is especially true in irritable bowel syndrome, where it has been my experience that it is very difficult for the patient to agree that the symptoms are purely functional.
The thought of some diseases strikes such terror in patients' minds that they insist on screening tests, even though no study has shown that a positive test leads to a clinical intervention that either saves or prolongs life. Screening for ovarian cancer with the CA-125 blood test plus a vaginal ultrasound immediately comes to mind. OTOH, abdominal aortic aneurysms do enlarge, rupture and kill the patient (as in the case of Albert Einstein who refused surgical treatment). Medicare will pay for one abdominal USG in a patient's lifetime if the first test is normal. "Cost effectiveness" would limit this study to the highest risk group: male smokers over 65, especially if they have hypertension. However, although the group incidence published in an article in Lancet was 11%, I am certain that if a patient was told that he/she had a 5% chance of having a possibly fatal condition, then they would want the ultrasound.
We do know how to treat many infectious diseases, so screening for tuberculosis, syphilis, AIDS, hepatitis B and Hepatitis C, all of which can be fatal if untreated, would seem to make sense, although there are no studies as to how often these tests should be offered if negative. One would think that screening for chronic kidney disease, which problem can lead to dialysis, would also make sense, but in the latest issue of the Annals of Internal Medicine the United States Public Service Task Force has come out against this. We can't even show that screening for diabetes saves lives, but we are on firm ground when we state that treating hypertension prevents strokes. Oddly enough, although untreated high blood pressure can cause heart failure, there is no clinical study that demonstrates that treating hypertension prevents heart failure. And although "everyone" agrees that a chest Xray is not needed in a non-smoker with no pulmonary symptoms, many anesthesiologists insist on a chest Xray before surgery if general anesthesia is to be used.
Every female of child-bearing age who comes to the emergency room is given a urine test for pregnancy. Should the same be done at every visit to a physician's office? Or before any Xray, including dental ones?
The prevalence of arteriosclerotic coronary artery disease at autopsy in 40 year old men is 10%. Should every man of this age have a stress-echo cardiogram as well as a thallium stress test? What about smokers and insulin-dependent diabetics and morbidly obese patients at age 30?
It makes clinical sense to do a complete blood count, because anemia can be treated and its cause found, and many leukemias can be cured. Similarly, deficiencies of vitamin B12, vitamin D and iron can be tested for and treated, as can elevated mercury, uric acid, and calcium levels as well as low magnesium levels. Whether patients who grew up in a country where parasites are endemic or who visited such countries should be screened for parasites has never been properly addressed, and such patients are usually only tested when they evince symptoms. I assume the physician would obtain the patient's permission before testing for such drugs as cocaine, amphetamines, opiates and benzodiazapenes. Another debated practice is that of obtaining a baseline EKG at the first office visit: no patient ever has a completely "normal" EKG, and it can make clinical sense to know what the EKG looks like before the patient's first visit to the ER with chest pain. And annual EKG's can detect the occurrence of a silent MI, but no studies have, to my knowledge, addressed the utility of this practice, although an unchanged EKG does bring a degree of mental comfort to the patient.
I have saved the thorniest problem for last. There are more and more OTC tests sold for patients to test themselves not only for a particular disease, but for risk factors for the disease. This is a real problem if the disease in question has no satisfactory treatment. And unless the false positive and false negative percentages are explicitly stated on the package along with the prevalence of the disease in the patient's population, he may well be needlessly worried or reassured. Clearly these tests will continue to be sold, but the patient should be firmly instructed by the pharmacist not to jump to any conclusions before discussing the results with his/her physician.
Let me close with an anecdote from my practice. When you donate blood, the Red Cross routinely screens for AIDS among other diseases, and confirms a positive screen with a Western Blot test which is the "gold standard". The WB is not used for screening because it is more expensive and labor intensive, much as syphilis is screened for with the VDRL and confirmed with the FTA. In the past, the flu virus for the vaccine was grown in human cell culture, and because of cross-viral antibodies, patients who received the flu vaccine would test positive for the AIDS virus on the screening test but negative on the Western Blot; this false positive existed for three to six weeks after the flu vaccine. I received a panicked phone call one December from a patient of mine who was a fraternity member at a Florida university where the fraternities were competing with one another in a blood bank drive. He told me that he and 25% of his brothers had tested positive on the screen, and what were they to do? Thankfully I was able to reassure him about the false positive once I had learned that they had all gotten the flu vaccine the previous week, and could tell him to wait for the Western Blot result. Of course, he could never again give blood, because although the Red Cross would officially tell them the Western Blot was negative and that they didn't have AIDS, they still would not risk using the blood.
One philosophical question arises when the patient asks for a test, blood or radiological, which the physician knows will be negative. Is there anything ethically wrong in ordering this test to give the patient peace of mind, assuming that the physician explains the probability of a false negative test and the problems and possible morbidity that can follow from acting on a false positive test? I think not. In some cases a negative test (e.g. a cardiac stress test in a patient suffering chest pain from a panic attack) will permit the physician to direct the patient's attention to the underlying problem. This is especially true in irritable bowel syndrome, where it has been my experience that it is very difficult for the patient to agree that the symptoms are purely functional.
The thought of some diseases strikes such terror in patients' minds that they insist on screening tests, even though no study has shown that a positive test leads to a clinical intervention that either saves or prolongs life. Screening for ovarian cancer with the CA-125 blood test plus a vaginal ultrasound immediately comes to mind. OTOH, abdominal aortic aneurysms do enlarge, rupture and kill the patient (as in the case of Albert Einstein who refused surgical treatment). Medicare will pay for one abdominal USG in a patient's lifetime if the first test is normal. "Cost effectiveness" would limit this study to the highest risk group: male smokers over 65, especially if they have hypertension. However, although the group incidence published in an article in Lancet was 11%, I am certain that if a patient was told that he/she had a 5% chance of having a possibly fatal condition, then they would want the ultrasound.
We do know how to treat many infectious diseases, so screening for tuberculosis, syphilis, AIDS, hepatitis B and Hepatitis C, all of which can be fatal if untreated, would seem to make sense, although there are no studies as to how often these tests should be offered if negative. One would think that screening for chronic kidney disease, which problem can lead to dialysis, would also make sense, but in the latest issue of the Annals of Internal Medicine the United States Public Service Task Force has come out against this. We can't even show that screening for diabetes saves lives, but we are on firm ground when we state that treating hypertension prevents strokes. Oddly enough, although untreated high blood pressure can cause heart failure, there is no clinical study that demonstrates that treating hypertension prevents heart failure. And although "everyone" agrees that a chest Xray is not needed in a non-smoker with no pulmonary symptoms, many anesthesiologists insist on a chest Xray before surgery if general anesthesia is to be used.
Every female of child-bearing age who comes to the emergency room is given a urine test for pregnancy. Should the same be done at every visit to a physician's office? Or before any Xray, including dental ones?
The prevalence of arteriosclerotic coronary artery disease at autopsy in 40 year old men is 10%. Should every man of this age have a stress-echo cardiogram as well as a thallium stress test? What about smokers and insulin-dependent diabetics and morbidly obese patients at age 30?
It makes clinical sense to do a complete blood count, because anemia can be treated and its cause found, and many leukemias can be cured. Similarly, deficiencies of vitamin B12, vitamin D and iron can be tested for and treated, as can elevated mercury, uric acid, and calcium levels as well as low magnesium levels. Whether patients who grew up in a country where parasites are endemic or who visited such countries should be screened for parasites has never been properly addressed, and such patients are usually only tested when they evince symptoms. I assume the physician would obtain the patient's permission before testing for such drugs as cocaine, amphetamines, opiates and benzodiazapenes. Another debated practice is that of obtaining a baseline EKG at the first office visit: no patient ever has a completely "normal" EKG, and it can make clinical sense to know what the EKG looks like before the patient's first visit to the ER with chest pain. And annual EKG's can detect the occurrence of a silent MI, but no studies have, to my knowledge, addressed the utility of this practice, although an unchanged EKG does bring a degree of mental comfort to the patient.
I have saved the thorniest problem for last. There are more and more OTC tests sold for patients to test themselves not only for a particular disease, but for risk factors for the disease. This is a real problem if the disease in question has no satisfactory treatment. And unless the false positive and false negative percentages are explicitly stated on the package along with the prevalence of the disease in the patient's population, he may well be needlessly worried or reassured. Clearly these tests will continue to be sold, but the patient should be firmly instructed by the pharmacist not to jump to any conclusions before discussing the results with his/her physician.
Let me close with an anecdote from my practice. When you donate blood, the Red Cross routinely screens for AIDS among other diseases, and confirms a positive screen with a Western Blot test which is the "gold standard". The WB is not used for screening because it is more expensive and labor intensive, much as syphilis is screened for with the VDRL and confirmed with the FTA. In the past, the flu virus for the vaccine was grown in human cell culture, and because of cross-viral antibodies, patients who received the flu vaccine would test positive for the AIDS virus on the screening test but negative on the Western Blot; this false positive existed for three to six weeks after the flu vaccine. I received a panicked phone call one December from a patient of mine who was a fraternity member at a Florida university where the fraternities were competing with one another in a blood bank drive. He told me that he and 25% of his brothers had tested positive on the screen, and what were they to do? Thankfully I was able to reassure him about the false positive once I had learned that they had all gotten the flu vaccine the previous week, and could tell him to wait for the Western Blot result. Of course, he could never again give blood, because although the Red Cross would officially tell them the Western Blot was negative and that they didn't have AIDS, they still would not risk using the blood.
Wednesday, August 22, 2012
Radiation and Radiation Sickness Part II
There are and will continue to be articles about the dangers of radiation, so I thought a few additional remarks about the basic physics of radiation and its effect on human tissue are in order. I will restrict my discussion to external radiation that occurs in the form of gamma rays, aka Xrays, and ignore alpha rays (helium nuclei), beta rays (electrons) and neutrons. I will just mention that the shorter the wavelength the higher the energy of the incident radiation, so that infrared rays have less energy than do ultraviolet rays, which is why UV rays can penetrate the skin more deeply and thereby create Vitamin D.
Xrays are a form of energy, travelling at the speed of light because they are composed of photons. We are exposed to Xrays from the earth's natural radioactivity, from medical Xrays, and from cosmic rays. Xray energy is often defined as the ability to ionize a column of air, but this definition from physics is not a useful definition for medical purposes. Instead we have the "rad" and the "rem", although "roentgen","curie", "gray" and "sievert" are in use in some places.
The rad is a unit of absorbed radiation dose, in other words it is the dose of Xradiation that is needed for a certain sample (animal, vegetable or mineral) to absorb a certain fixed amount of energy per gram of material. It is thus clear that the rad depends on the wavelength, i.e. the energy of the incident radiation as well as the absorptive properties of the material. The rem, or "roentgen equivalent man" is a measure of the biological effects of the absorbed radiation, which is clearly not only dependent on the wavelength of the incident radiation but also on the tissue (brain, bone marrow, thyroid gland, etc.) that is absorbing the radiation. I should here mention that different countries and different international organizations have different conversion factors from rad to rem. It is also obvious that it is impossible to determine the precise rem value of incident radiation on man because we have no way to examine living human tissue after exposure to radiation to determine its biological effect, so the conversion factors are "guesstimates".
The idea that the risk of cancer increases linearly with Xray dose rate is a consensus decided upon by international bodies, and has no demonstrated basis in clinical fact. The risk is really stochastic rather than deterministic. It is also stated, without clinical evidence, that the risk is higher for children and fetuses than for adults, and higher for women than for men. The international recommended "safe" exposure dose from medical Xrays and other sources over and above environmental exposure is 0.1 rem/year, but this is also a consensus number with no demonstrated basis in fact. For comparison, because of their higher altitude and therefore less shielding by the atmosphere, residents of Denver are exposed to an additional 0.3 rem/year, and airplane crews are exposed to between 0.5 rem/year to 1.0 rem/year, depending on their routes. BTW, the International Commission on Radiological Protection recommends evacuation of any area where the excess dose of radiation is greater than 0.1 rem/year, even though residents of Denver have a lower cancer incidence than do residents of the flatlands. I also have found no published clinical studies demonstrating that women who have mammograms have a higher incidence of breast cancer than women who never had a mammogram.
Addenda: All granite contains some uranium and therefore exhibits low-level radioactivity. We have no good model as to whether or not Xradiation is teratogenic. The International Committee for Weights and Measures does not accept the rad as a unit of radiation exposure, but this unit is widely used in the U.S. The lethal dose of radiation depends upon the time frame over which it is delivered, which is why radiation therapy for cancer is spread out over weeks. In general, a dose of 1,000 rads delivered over a few hours will be lethal, and doses of 100 to 1,000 rads over a few hours will cause acute radiation sickness, with the probability of dying being greater of course at the higher dose.
Xrays are a form of energy, travelling at the speed of light because they are composed of photons. We are exposed to Xrays from the earth's natural radioactivity, from medical Xrays, and from cosmic rays. Xray energy is often defined as the ability to ionize a column of air, but this definition from physics is not a useful definition for medical purposes. Instead we have the "rad" and the "rem", although "roentgen","curie", "gray" and "sievert" are in use in some places.
The rad is a unit of absorbed radiation dose, in other words it is the dose of Xradiation that is needed for a certain sample (animal, vegetable or mineral) to absorb a certain fixed amount of energy per gram of material. It is thus clear that the rad depends on the wavelength, i.e. the energy of the incident radiation as well as the absorptive properties of the material. The rem, or "roentgen equivalent man" is a measure of the biological effects of the absorbed radiation, which is clearly not only dependent on the wavelength of the incident radiation but also on the tissue (brain, bone marrow, thyroid gland, etc.) that is absorbing the radiation. I should here mention that different countries and different international organizations have different conversion factors from rad to rem. It is also obvious that it is impossible to determine the precise rem value of incident radiation on man because we have no way to examine living human tissue after exposure to radiation to determine its biological effect, so the conversion factors are "guesstimates".
The idea that the risk of cancer increases linearly with Xray dose rate is a consensus decided upon by international bodies, and has no demonstrated basis in clinical fact. The risk is really stochastic rather than deterministic. It is also stated, without clinical evidence, that the risk is higher for children and fetuses than for adults, and higher for women than for men. The international recommended "safe" exposure dose from medical Xrays and other sources over and above environmental exposure is 0.1 rem/year, but this is also a consensus number with no demonstrated basis in fact. For comparison, because of their higher altitude and therefore less shielding by the atmosphere, residents of Denver are exposed to an additional 0.3 rem/year, and airplane crews are exposed to between 0.5 rem/year to 1.0 rem/year, depending on their routes. BTW, the International Commission on Radiological Protection recommends evacuation of any area where the excess dose of radiation is greater than 0.1 rem/year, even though residents of Denver have a lower cancer incidence than do residents of the flatlands. I also have found no published clinical studies demonstrating that women who have mammograms have a higher incidence of breast cancer than women who never had a mammogram.
Addenda: All granite contains some uranium and therefore exhibits low-level radioactivity. We have no good model as to whether or not Xradiation is teratogenic. The International Committee for Weights and Measures does not accept the rad as a unit of radiation exposure, but this unit is widely used in the U.S. The lethal dose of radiation depends upon the time frame over which it is delivered, which is why radiation therapy for cancer is spread out over weeks. In general, a dose of 1,000 rads delivered over a few hours will be lethal, and doses of 100 to 1,000 rads over a few hours will cause acute radiation sickness, with the probability of dying being greater of course at the higher dose.
Subscribe to:
Posts (Atom)