Correlation Does Not Mean Causation

Examples:

1. Shoe size is directly correlated with neat handwriting. Does this mean that there is something about increased shoe size that causes neater writing? Or is it because older children wear larger shoe sizes and by virtue of age, are more mature and write more neatly than toddlers? The correlation does not mean causation.

2. The number of drownings is highly correlated with the time of year, namely summertime. This does not mean that summertime causes drownings. There are more drownings because more people swim in the summer.

3. Myocardial infarctions are correlated with elevated troponin levels. This does not mean that troponin levels cause myocardial infarctions. It would be a mistake to try to treat heart attacks by lowering troponin levels, when in fact it is the MI that causes the elevated troponins, which leak out of damaged myocardial cells. Too obvious? How about the following:

4. Elevated blood homocysteine is correlated with increased risk for myocardial infarction. Does elevated homocysteine cause heart attacks? Studies designed to decrease homocysteine have not demonstrated any lessening of the risk for MIs. Perhaps a third factor causes a rise in homocysteine as well as a susceptibility to MIs.

5. Elevated LDL cholesterol is correlated with increased risk of cardiovascular disease. If a third factor (e.g. stress, heredity) is the cause of both cardiovascular disease and elevated LDL, it may not help to try to control arteriosclerosis by taking years of anticholesterol medication. Current medical opinion leans heavily toward LDL cholesterol as a causative act in cardiovascular disease, but there are those who disagree.

6.  Hypertension is believed to cause arteriosclerosis. But could a third factor (e.g. stress) be implicated as a cause of both?

6. According to a 2005 study in Finland, women who have abortions are more likely to commit suicide. Do abortions cause suicide, or are women who have abortions more likely to be in social situations that in themselves are more likely to promote suicide? Women who have abortions also are more likely to be murdered and die in accidents. If they are already high-risk for murder, suicide, and accidents, they may be more likely to be in situations where they choose an abortion.

7. People often are quick to judge patterns and often attribute causal importance to patterns that are only coincidental. I had an elderly patient who was sure he knew what caused Parkinson’s disease; he had purchased his home from someone who had Parkinson’s disease, and a year later he, too, was diagnosed with Parkinson’s disease. In his mind, it must have been communicable. However, about 1 million people in the USA have Parkinsonism, mostly people over 60. The chance that the person purchased the home from someone with Parkinson’s and also would acquire the disease is not so unreasonable, given the number of people who buy homes and the prevalence of Parkinson’s disease. In addition, there are thousands of other diseases that both buyer and seller might have had coincidentally. The chance that at least one of those diseases could have occurred in both buyer and seller is high. The clincher here was pointing out that the spouses of patients with Parkinson’s disease do not have a higher incidence of the disease than those not married to someone with Parkinson’s. One of the biggest mistakes in research is confusing correlation with causation.

8.  A study indicated that smiling a lot is correlated with a longer life. Should we then go around forcefully smiling at everyone like the Burger King king? Maybe good health induces people to smile more.

9. If people who take Dynamo MaxiForte vitamins have a lower risk of illness, is it because of the vitamins or because they take care of their health needs in other ways, too, such as exercise and a balanced diet?

10. Teenagers who spend a lot of time texting and on social network websites have a higher incidence of sex, stress, substance abuse, depression, and fighting. Should texting therefore be decreased? Which variable causes which?

The medical and popular literature is rife with examples of confusing correlation with causation. One must be on the alert not to confuse the two.

New MedMaster Editions in Microbiology and Critical Care

CLINICAL MICROBIOLOGY MADE RIDICULOUSLY SIMPLE (ED. 8)

This best-selling, updated approach to clinical microbiology, brims with mnemonics, humor, summary charts and illustrations; includes all the classic and emerging infectious diseases, with a brand new chapter on the SARS-COV-2 virus, its diagnosis, treatment and immunization. In regular, spiral-bound, or ebook format. ISBN 9781935660484

CRITICAL CARE & HOSPITALIST MEDICINE MADE RIDICULOUSLY SIMPLE (ED. 2)

The new second edition of this best-seller includes a separate chapter on the diagnosis and treatment of COVID-19 in critical care settings. Now in ebook format.

New MedMaster Titles in Genetics and Hematology

CLINICAL GENETICS MADE RIDICULOUSLY SIMPLE

The burgeoning field of Genetics is a complex and formidable topic for the student and practitioner. It is easy to get lost in the forest for the trees since genetics lends itself anywhere from a basic foundation of DNA and its parts, to a more complicated and nuanced understanding of how these parts work together, what happens when things go wrong, how to diagnose and treat genetic disorders, and the latest advances and areas of hope in genetic research.

Clinical Genetics Made Ridiculously Simple presents a way to rapidly visualize the field as a whole, including basic genetics, chromosomal abnormalities, epigenetic disorders, cancer, screening tests, gene sequencing, CRISPR, COVID-19 immunization in relation to genes, homeobox genes, and changing approaches to the clinical diagnosis and treatment of genetic conditions.

The author builds from the basics of genetics and DNA, an understanding of how our genetic material functions, what it means to have a genetic defect, what we presently know about these defects and newer therapies for these problems. Each topic is carefully taught, one step at a time, so that the student is never lost, all in 112 pages! $24.95.

HEMATOLOGY MADE RIDICULOUSLY SIMPLE

Clinical Hematology Made Ridiculously Simple is a brief, clear, practical overview of the range of hematologic disorders, with their diagnoses and treatments, all in 85 pages. The topics include the Complete Blood Count (CBC), disorders of red blood cells (the anemias, iron overload, polycythemia), platelets and blood clotting, white blood cells and the immune system, the leukemias and other hematologic malilgnancies, and blood transfusion. $24.95.

Medicine’s Alternative Universe

by S. Goldberg, Med’Toons, Medmaster

An alternative universe is an unseen dimension. When we round and enter the patient’s room, we don’t experience this hidden dimension, just our own world with its medical technicalities.

The hidden dimension is the hospital experience from the patient’s point of view. The patient is not necessarily thinking what the therapist is thinking. I entered this dimension recently after undergoing coronary artery bypass graft (CABG) surgery.  Here are my impressions of the physician’s dimension as opposed to the patient’s dimension during evaluation and treatment:

On being wheeled in a bed to angiography and by-pass surgery that night:
PHYSICIAN: Wheel the patient to the procedure room, adequately sedated.
PATIENT: Nervous; too late to change my mind. As one patient put it “Imagine someone sawing your chest in two and pulling you asunder and then doing some crazy shit to your heart?”  Lying in bed, I don’t have to do any of the wheeling. I’m a VIP from Hell.

Immediately post operation:
PHYSICIAN: Family visitations OK in ICU.
PATIENT: Family scared looking at me recovering from anesthesia. They heard a lot of moaning (which I don’t remember) and thought I might die. I can’t engage in meaningful conversation with them. I don’t look so great the rest of the hospitalization either.

PHYSICIAN: After admission to ICU; remove endotracheal tube (I don’t remember that); monitor vital signs; chest tube should be draining; Foley catheter in place; measure urine volume; IV drip with correct medication flowing at an optimal rate; nasal cannula in place with adequate flow; arterial line from angiography remains in place in groin in case arterial access is needed.
PATIENT: Groggy; pain on respiration largely from chest tubes; have to stay still and supine so as not to disrupt arterial line in right groin. Uncomfortable. I’m used to turning from side to side when I sleep. Can’t do that now.

During 6 days of hospitalization:
PHYSICIAN: Throughout each night, draw blood tests; check oxygen saturation; give medication; check BP, pulse and ECG.
PATIENT: At 3AM every night? Can’t sleep well as is, especially with the background noise and light; try sleep mask and ear plugs; can’t find good sleeping position; have to frequently call nurse to adjust body position; after a few days, need to sleep in chair part of night. So many pills; should I take them all at once or one at a time? Better take one at a time so I don’t choke. What if I arrest? Would they give me chest compressions with this fresh chest wound? Bed pan no fun. You never hear about bed pans in movie plots.

PHYSICIAN: Respiratory therapy – instruct patient how to use volumetric spirometer; administer respiratory inhalant in the middle of the night.
PATIENT: The respiratory therapist is encouraging, but I’m not going to break any Olympic records for volume of inspiration with this spirometer.  Inspiration with the device difficult due to coughing.

PHYSICIAN: Have patient sit in chair, not in bed all the time.
PATIENT: Need warm blankets, since I’m cold. The staff is busy. Not me. Nothing of interest on TV. I specialize in staring into blank space. Can’t work; depressed. Life is accelerating downhill. What about my family? My work? I don’t want to be a burden.

PHYSICIAN: Ambulate patient after 1 day.
PATIENT: Legs feel heavy; hard to stand or walk; in danger of fainting; need assistance in walking short distances, with shuffling. Need a walker; who, me? I’m a patient now!  I think the only difference between being sick and dying is that you don’t get better with dying. I’m walking a little better each day.

PHYSICIAN: Give patient colchicine to reduce cardiac inflammation.
PATIENT: Colchicine causing diarrhea. Hard enough getting out of bed with assistance to go to toilet, and, with all these IVs, need my butt wiped by the nurse.

PHYSICIAN: Time to remove 2 of the 3 chest tubes on day 2; leave one of them in, maybe until tomorrow, since there still appears to be significant fluid in the lungs.
PATIENT: Please take out that last tube tomorrow so that I can breath better with less pain.

PHYSICIAN: Surgery group says chest incision looks good.
PATIENT: It may look good, but it feels more like in the Alien movie before the alien burst from the chest. I guess it’s “better to look good than to feel good.” But I’m glad I’m still above ground. I’m growing a beard; look scruffy and old.

PHYSICIAN: Apply automatic inflatable cuffs pumping continually on calves to help prevent clotting.
PATIENT: Helpful, but another restriction to moving.

PHYSICIAN: Take frequent BP readings, with cuff remaining in place.
PATIENT: Cuff causes an irritating blister under my left arm and has to be moved to the right.

PHYSICIAN: Keep IV going.
PATIENT: IV is infiltrating, blowing up around the needle. Will the nurse come? I’m running out of veins. Was that the last vein available? What will they do if I run out of veins!?

PHYSICIAN: Keep controller near patient to control TV, adjust bed, and enable patient to call nurse.
PATIENT: Help, I can’t find the controller. I’m doomed, unless I yell for assistance. Would they come?

PHYSICIAN: Keep track of urine volume.
PATIENT: I find the male bed urinal difficult to use. Which way? Up or down? I wet the gown and bed; hard to pee when supine; need to stand up.

PHYSICIAN: Administer prescribed diet.
PATIENT: Not hungry; ate little.

PHYSICIAN: Do direct stick for arterial blood gases.
PATIENT: More like several painful sticks; apparently harder to get arterial blood than venous blood; also I’m collecting an assortment of ugly purple patches from blood leaking under my skin. I’m looking more like a patient.

PHYSICIAN: Incisions in right leg to get vein for grafting is healing well.
PATIENT: I forgot that I have more incisions.

PHYSICIAN: Take patient down for x-ray.
PATIENT: I’m down in Radiology, but no one is coming. How long will I wait?

PHYSICIAN: Once outside ICU, arrange consultation for the Surgical team, Pulmonary, Internal Medicine, Cardiology, Physical Therapy, Social Services.
PATIENT: I’m losing track of all the consults. Nursing care very good, but more attentive in ICU where there is higher nurse-to-patient ratio. Medical consult passes through quickly. Does he really care, or has the bedside just become routine and impersonal? Does he know anything about me other than the lab values?

PHYSICIAN: Pain Medication PRN.
PATIENT: I don’t want to take any more meds than necessary. Pain improved on removing chest tubes, but have pain in back, shoulders, and neck, maybe from awkward sleeping position or the surgery itself. Maybe just Tylenol.

PHYSICIAN: Discharge patient, 6 days post-op.
PATIENT: On 11 different medications!!?? Discharge group conference discussed diet, activity, nursing and physical and occupational therapy visitations for 2 weeks, followed by cardiac rehab in 1 month post-discharge. Regarding depression, the group answered any questions and pointed out that I would feel better in time. They did a good job.

Start cardiac rehab 1 month post-op. Exercising more in Rehab; feeling better than I have in a long time 2 months post-op. I am grateful for a new heart. Another benefit: weight loss.

I wrote this blog entry to remind the student and physician that there is another dimension to making rounds, that of the patient’s feelings and point of view. Regretfully, empathy with the patient often diminishes in the latter years of medical school, probably due to lack of time and the mass of technical information that has to be absorbed, in addition to the stress of being personally involved with patient and family. Rather than quickly passing by the bedside on rounds, sit down for a minute with the patient to empathize at the patient’s level. That is also therapy. Do you know who your patient is? Is he/she just “the CABG in room 612?” The patient “won’t care how much you know until they know how much you care.”

Should USMLE Step 1 Be Eliminated, Modified, Or Open-Book?

“Now this shouldn’t hurt a bit!”
From Med’Toons, by S. Goldberg, Medmaster

At first glance, Step 1, which emphasizes basic science knowledge and is taken after the second year of medical school, would seem necessary to insure that medical students have achieved the proper level of knowledge to proceed in their education.  However, there is another consideration.

I cannot help but notice the great amount of time spent by students discussing how to pass the medical Boards; students are compelled to spend a great deal of time in rote memorization of esoteria for the exam; otherwise they may not pass.  In my view, this emphasis interferes with the need for students to acquire a proper understanding of the topics discussed in the first two years, understanding that is vital in taking care of patients.

Today, it is relatively easy to electronically search for isolated points of information through apps and the Internet; there is less need for rote memorization, which computers do best, and greater need for understanding, which humans do best.  Despite the information explosion, surely there is less need to memorize so much and greater need to promote understanding of the clinical material as a whole.

Even the best physicians may have trouble with questions on the Boards. We would like to gear medical education to turning out the best physicians.  But what constitutes an excellent physician?:

• Most cases a physician sees are common situations rather than zebras.  Good medicine is largely a matter of applying common knowledge and principles to diagnosis and treatment, without getting sloppy, rather than coming up with a roundsmanship coup. The excellent physician does not, to save time, routinely order, in a shotgun fashion, all manner of rare, invasive, and expensive low-yield tests.  Nor does the excellent physician hastily rush to decide on a diagnosis based on a too-quick, superficial initial impression. The best physician is not necessarily the one who has the greatest knowledge base, but the one who consistently and meticulously applies common knowledge.

• Patients do not care so much about the physician’s medical school or residency diplomas as they do care about how the physician responds to them as individuals, whether the physician is compassionate, and allots the patient the necessary time.  “Patients do not care how much you know, until they know how much you care.”  This aspect of medicine is also important, just as is the knowledge base.

• The good physician, unless there is an emergency, schedules reasonable office waiting times, promptly notifies patients of lab results, follows up on the patient’s progress, and adopts more than just a cookbook approach to diagnosis and treatment. Medical education needs to emphasize understanding of important concepts, as well as familiarity with where and how to search for isolated points of information, which have grown too large for anyone to remember.  This is not emphasized on the Boards.  Emphasizing understanding, something Medmaster has focused on for the past 34 years, may seem to be a minimalistic approach to education, but in fact it is a maximal approach, insuring that the student acquires the greatest degree of understanding. Every patient is different, and a cookbook approach may not work for all patients; understanding  what one is doing is critical to good patient care.

So, should Step 1 of the USMLE be eliminated, or modified? Perhaps Step 1 should be an open-book exam; this would more resemble everyday practice, where physicians now have ready access to point-of-care information. What do you think?

Revamping The Med School Curriculum

From Med’Toons, by Stephen Goldberg, Medmaster

Having taught medical students for 25 years, practiced in several different medical fields, edited all the Medmaster titles in the basic and clinical sciences, and received feedback from many instructors and students through the years, here is how I would revamp the medical curriculum:

1.  I would continue learning the basic sciences in the first two years, followed by 2 years of clinical experience, as opposed to the idea of learning the basic sciences and seeing patients right from the start.  While one may want to see patients as soon as possible, it is better to first learn the basics, since you can then approach medicine with overall understanding, rather than scattered facts.  It is like the juggler, who needs to combine a number of different skills to perform, such as simultaneously juggling 6 balls, twirling 3 hoops around one foot, and balancing a stick on his head.  He would do better by first learning each skill separately and then putting them together, rather than trying to learn by practicing all of them together from the start.  The basic sciences, though, should not be taught without reference to clinical medicine; they should be taught with a clinical emphasis, showing the clinical relevance of each subject as it is taught.

2.  While small group discussions of clinical cases in the first two years can be an excellent source of learning for a given case, they tend to be an inefficient way to learn.  They are time-consuming and cannot get into the vast amount of medicine that has to be learned.  Also, when scheduled in the basic science years, they are presented too early for an adequate understanding of the topics, since the student has not yet learned the underlying basic science.  While case discussions in the basic science years provide a way to introduce clinicians into the discussion (as most basic science courses are taught by PhDs, rather than clinicians), clinical relevance can be introduced more efficiently through well-designed reading, audio, and video presentations.

3. There is an overload of information in the medical curriculum today.  We need to focus on general principles and understanding as opposed to numerous esoteric facts. People are much better at understanding than rote memorization, while computers excel at memorizing detail.   The game-changer in today’s education is that it is easy to search for facts as needed on electronic media such as the Internet, in contrast to the past, where one had to rely on the latest reference texts and printed journals or go to the library to search through tomes of Index Medicus for relevant articles.

By the end of medical school we forget many of the facts that we learned.  And we do not acquire an overall understanding of many topics because of the deluge of information that we are hit with over the four years; we do not see the forest through the trees.  It is better to acquire overall understanding and know where to search for further detail.  Learning general principles with understanding is in itself a fulltime job.

4.  I would, for the most part, eliminate classroom lectures.  Lecturers vary in quality, and even when there is an excellent lecturer, it can be difficult keeping up with note taking and grasping what is being said in a fast-talking delivery, especially when tired after staying up late.  Why sit through a classroom lecture when one can learn the same thing through a YouTube or other video venue, at one’s own time and pace, and stop and go back to review points for clarification? I think the best use of the future instructor will not be to deliver a lecture in a classroom, but as a facilitator in pointing to the best educational sources for the student and responding to student questions.  Where an instructor has something special to relay to the student that cannot be found elsewhere, it often would be better to present it as a personal reference video than as a classroom lecture.  The instructor should, however, be available for individual questions from students, whether in person or by electronic communication.  This will not only be better educationally for the student, but for the basic science instructor, who in many cases would prefer to spend more time in research activities. Rather than repeating the same lecture many times, the instructor can point to a well-designed video that can be accessed by different classes.

5.  There should be a detailed list that the student receives on entering medical school as to what material in the basic sciences to learn, with recommendations as to where to find the information.  The student should largely learn independently. There should be periodic tests to insure that studying is not crammed in toward the end, when the tests are given.

The same should apply in the clinical years. The student should have a list of the most important clinical conditions, with suggestions as to the most reliable learning resources to diagnose and treat them, whether they are books, apps, or videos. As is, education in the clinical years is often not organized, with the student left on his/her own to determine what is important to learn. As in the basic sciences, there should be periodic tests of knowledge.  Learning through direct patient care is also very important, perhaps the most important way of all to learn.  After seeing patients in the hospital each day, the student should seek out information as to differential diagnosis and treatment of the conditions seen that day.  The student cannot learn everything, but by focusing mainly on the illnesses of the day, at the end of the four years the student will have studied the most common diseases.

6.  Exams, including the Boards, should not present ‘gotcha’ questions, but basic information highly relevant to practice.  So what if the questions are so basic that nearly everyone can succeed at the tests.  They should be designed to confirm that the student has the necessary practical knowledge base. With the time saved by teaching general principles and promoting understanding in the basic sciences, rather than an overload of esoteria, the student will have more time to review for the Boards and study medical topics of personal interest.

7.  While this may seem to be a “minimalist” approach to education, it is not.  In the end it would maximize a student’s overall understanding of medicine, while inculcating a lifelong method of seeking out detailed information as needed.

What do you think?

Should Lectures Be Eliminated in Medical School?

Lectures have always been a staple way of educating in medical school, particularly in the first two years.  But are they the most efficient way to learn?

PROS:

•  There are excellent lecturers, who can provide insights and important points not presented in other sources.

•  The lecturer, as a facilitator, is available to the student for clarification of ideas that are not clear.

•  Lectures provide a different avenue of learning that can add to the learning experience.

CONS:

•  You can’t just stop in the middle of a lecture to mull over the ideas, or go back, as you can with a book or an electronic presentation.  Key points may be missed, especially if you can’t write fast enough.

•  Students learn at different paces, and books and computer programs allow students to learn at their own speeds.  The quality of computer teaching programs is continually improving.

•  In cases where a lecturer speaks poorly, or does not teach with clinical relevance, would it not be better to use computers or clinically relevant texts to learn?

•  Some lecturers in the basic sciences may be excellent researchers who would make better use of their time in the research lab, where their talents and interests lie.  The department could also save money by hiring fewer lecturers.

•  Clinicians can be good sources of clinically relevant information, but are often too busy to put in a consistent teaching schedule.

Some students do not show up at lectures, and others do so because it is more likely that what a lecturer says will show up on an exam.  Others rely on note takers.

Should the emphasis on lectures be reduced?  Should more teaching shift to self-learning?  Would it be better to provide students with a list of clinically important concepts and points to learn in the basic sciences and then allow the students to learn them at their own pace?

What do you think?

Medical Curriculum In The First Two Years Of Med School

 Say you have a juggler who wants to be the best ever, to juggle 7 balls at the same time as balancing a stick on his head and twirling 3 hoops around his leg.  How would he go about learning this amazing stunt, which combines three skills?  You might say to start off practicing all of these skills together, since this is the final result the juggler wants to achieve.  However, the juggler is more likely to succeed by practicing one skill at a time, and then, after learning each of them, practicing them together.

 It is similar in working with patients.  In evaluating patients, it is important to incorporate the considerable information you have acquired in the basic sciences.  For that reason, medical school education in the past consisted of spending the first two years learning the individual basic sciences and then putting this information together when seeing patients.

More recently, however, the trend  in some schools is to start right from the beginning seeing patients, before there is a background in knowledge.  Is this the best way to learn medicine?  I suspect that a leading reason for the change to seeing patients  right away is the impatience at having to wait so long before entering the clinical world.  In particular, since the basic sciences are typically taught by non-clinicians, and much emphasis is on information that the student does not find relevant clinically, the student wants greater clinical exposure right from the start.

 It seems to me that the better way to approach medical education in the first two years is the old way of learning the basic sciences first, but with a strong clinical emphasis, minimizing information that does not have clinical relevance.  By cutting down on the more esoteric, clinically non-relevant information, there would be more time in the second year to  study for the USMLE Step 1 (an exam taken at the end of the second year), put the information together, and better prepare for seeing patients.

 You, as a student, may have little control over how your school arranges the curriculum, but should not feel as if something is wrong with you if you feel somewhat lost in evaluating patients before you are prepared.  Some schools may offer the student a choice of following the more traditional curriculum or following one that emphasizes early clinical exposure.  Personally, I would opt for the former, but use a text that emphasizes clinical relevance.

 What do you think?

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