Episode 45: Sample this preventive medicine from the USMLE Audio Series at Medical-School-Podcast.com


Preventive Medicine

Preventive medicine, basically, has three tasks – screening, counseling, and immunization.  We are going to be focusing on screening and immunization.  About 15 minutes we’ll go over some screening principles, 15 minutes we’ll go over some principles regarding immunization.

Primary Prevention

So when you talk about preventive medicine and prevention, you can talk about it and think about it as primary prevention, secondary prevention, and tertiary prevention.  In primary prevention, you are actually working on reducing risk factors before a disease or a condition has occurred – so, immunizing somebody so they don’t get tetanus, you know, treating somebody who doesn’t have coronary artery disease with hyperlipidemia therapy to prevent them from getting heart disease.

Secondary Prevention

Secondary prevention talks about detecting a disease or a condition to improve prognosis – to do a mammogram to get an early stage breast cancer where that disease will be treatable and curable.

Tertiary Prevention

Tertiary prevention is another concept we don’t think about that much, but that would involve reducing risks of getting a second event.  So, if somebody has coronary artery disease, you put them on a high dose hyperlipidemic therapy to prevent their – or reduce their incidence of getting a follow-up disease.

There are a number of terms that you need to know in preventive medicine – that are listed up here.  These are covered very nicely in your book in chapter four.  And I believe Dr. (Stoller) will be reviewing some of these at the end of the day as well.  So, I’m not going to touch on these.

Screening Tests

So let’s talk about screening.  What are the general principles of screening?  Well, the disease that you’re screening for or condition should be important – meaning it should have a significant morbidity or mortality.  It should also be common.  It should have a high prevalence and a high incidence.  The disease that you screen for, you should be able to treat.  And the tests that you use to screen should be accurate, getting at the sensitivity, specificity, and predictive value.

Costs of Screening

And, finally, the screening tests should have a reasonable cost, not only financial in regards to quality of the life you’ll save, but also to the patient.  A screening test should be a low-risk test.

So when you look at the – number one – two causes of mortality in United States in 2002, you can see that the big players are heart disease and cancer.  So these are the ones who we would want to screen for the most.  And, obviously, the age where you screen somebody or practice preventive medicine varies.  So, obviously, in your older population, heart disease and cancer will be much higher on the list, whereas in your younger population, accidents, suicide, homicide, unfortunately, has a higher prevalence.

This very interesting slide shows the change in the United States death rates by cause between the years 1950 and 2002.  You can see that there has been a marked decrease in the rate per thousand deaths for heart disease, cerebral vascular disease, and also infection disease.  But the curve or the bar graph for cancer is relatively flat.

So let’s talk about, briefly, a couple of slides about cardiovascular screening.  We don’t have time today, but I think this will be covered at other sessions during the course about screening for blood pressure, lipid guidelines, diabetes guidelines.

EKG Screening?

I wanted to just make sure that you are aware.  According to the United States Preventive Services Task Force, if you have a 40-year-old patient who comes in without any risk factor who is healthy, there is no indication to do routine stress test screening or really routine EKG.

Another thing that you should be aware of is a new recommendation that came out this past year – I believe, officially, in March.  The United States Preventive Services Task Force had given a recommendation that all men between the ages of 65 and 75 who have ever smoked should have a one-time screening abdominal ultrasound looking for a triple A.  They give this a B recommendation – and we’ll go over the letter grades in a second.  They at this point in time do not recommend screening in all men ages 65 to 75, and they’re actually against, recommend against screening for triple As in women.  So, this you should be aware of.

Grades of Recommendations: A, B, C, D, and I

We’re going to talk some more about the United States Preventive Services Task Force, probably the best evidence-based guide that we have for preventive medicine in the United States.  They give all their recommendations with letter grade:  A and B, basically they recommend; C, there is no recommendation, there may be benefit but the data isn’t in at this point; and D are situations where it’s felt that harms outweigh any benefits; and an I recommendation, which they’re trying to avoid more and more, is that simply saying they don’t have enough evidence to make a decision.

Cancer Screening

I think you’ve seen a slide similar to this in Dr. (inaudible) talk.  When you estimate the top five U.S. cancers in the United States, prostate cancer and breast cancer are number one in men and women; followed by lung cancer, number two; and colon cancer, number three.  So these are the important, most common players.

For those of you who like to look at graphs, you can see the incidence right here of prostate cancer on the top, lung, colon cancer.  You can see that the rates for lung and colon incident rates are falling a little bit.  Prostate cancer is fairly steady.  That high PQt was the introduction of PSA into the screening.  This is the same slide for women looking at breast, colon, and lung cancer.

Somewhat sobering statistics, if you look at estimated risks of developing cancer for men, prostate cancer is one in six, but if you look at every cancer that you can get, including basal cell cancers and everything, we all have it – the men in this room, one in two chance of getting some cancer.  It’s not that much better for women – a one in three chance with the one and seven chance of developing breast cancer.

But these are not the cancers that kill people.  The still biggest killer of individuals from a cancer’s standpoint in both men and women are lung cancer, followed by prostate and breast cancer, followed by colon cancer.  Again, graphically, you can see the death rates for lung cancer are much higher in men than prostate and colon cancer.  And a similar graph for women, you can see that line for lung cancer has increased really since 1965 and onward as women have started to smoke more.

So let’s go do a couple cases that will hopefully review some basic principles about screening.  Now, this is, as I said, meat and potatoes, so I want to see like a 100 percent here.


So you have a 52-year-old guy, he comes in for a physical.  He has a past medical history of hypertension.  He’s only on hydrochlorothiazide.  He drinks one beer a day, and he quit smoking recently, although he had a 20-pack-year history.  Family history reveals a father with coronary artery disease at age 65 and a maternal uncle who had colon cancer at age 75.  Since he’s above 50, he thinks he’s getting old and he wants to get tested for cancer.

Colon Cancer Practice Question:

So, in regards to colon cancer screening in this 52-year-old guy, what would you recommend or what would be an acceptable answer?

A. Colonoscopy

B. Flexible sigmoidoscopy

C.  Hemoccult cards and flex sig

D. A and C

E. All of the above

Forty-three percent said colonoscopy, 35 percent said A and C, and 14 percent said all of the above.

I would say for a – if you look at recommendations, all of the above would be the correct answer.  All would be considered acceptable.  We may feel that colonoscopy is better, but for somebody who doesn’t want a colonoscopy, anything is better than nothing.

And so when we look at these guidelines, I’m going to focus on a few.  We already talked about the United States Preventive Services Task Force.  We’ll also go over all the American Cancer Society recommendations and we’ll throw in some subspecialty societies as well.

So the case about colon cancer, the official guidelines from the American College American Cancer Society, which has not changed since 2003, are beginning at age 50, a man or a woman should have either fecal occult blood testing every year; a flexible sig every five years; annual fecal occult blood test or a flex sig every five years; a double contrast barium enema every five years – no one else recommends this, I should note – or a colonoscopy every 10 years.

In our gentleman who had a maternal uncle who had colon cancer at 75, that really does not put him into the high risk category.  He will still be considered an average risk screening.

For the United States Preventive Services Task Force basically says that they give it an A recommendation that everybody over 50 should be screened.  They don’t give any recommendations about how to screen.  The American College of Gastroenterology basically says the same thing – either a colonoscopy every 10 years, or a flex sig every five with annual fecal occult blood testing.

Prostate Cancer Screening

Let’s talk about the same patient, what would you recommend screening for him for prostate cancer or what would be acceptable to do?  Do a rectal exam, PSA, both; or do nothing?  Seventy-one percent say yes, which I would do as well.  This is a question that you won’t see on the boards because, theoretically, depending on who you listen to, any answer could be correct.

And let’s go through the official guidelines.  The American Cancer Society basically says that age 50, men should undergo both the PSA and the digital rectal exam annually if you have a life expectancy of 10 years.  So in my own practice, I tend to stop routine PSA screening around 75 because if you look at a man, once they get to the age of 75, their average life expectancy is about 10 years.  So that’s when I have chosen to stop.

Men at high risk – family history, African-American race – start screening five years earlier – 45.  The United States Preventive Services Task Force basically says, “Well, we can’t tell you what to do.  There’s no information really out there.  If you don’t want to screen anybody, you’re in your right.”  But as you know, I think practically most of us – 71 percent of us – screen.

Cervical Cancer Screening

Now, let’s turn our attention to a younger patient.  Here we have a 20-year-old female coming in for a physical – no significant past medical history, she’s sexually active with one partner for the past seven months.  They use condoms about 75 percent of the time, her review of systems is negative, and she says that she has had normal Pap smears, her last one she had was two years ago and it was normal.  That was her second Pap smear ever.

So what are you going to recommend for cervical cancer screening in this 21-year-old patient?  Should she undergo annual Pap test?  Should you do a Pap test now and then if it’s normal, check again in three years?  Should you do annual Pap smears until you have two normals and then every three years?  D, should you do an annual Pap smear with human papillomavirus screening or should you do Pap smears and human papillomavirus screening every three years?

So a nice mix there.  The number one answer was C – annual Pap smears and two normals.  I would say the correct answer is A –  annual Pap smears.  And this can get confusing, so let’s go through this.  The American Cancer Society says that you should start screening for cervical cancer three years after a woman begins having vaginal intercourse or sooner, but no later than 21.  This used to be 18.  It’s been moved up to 21.

During this time period, screening should be done every year with regular Pap tests or every two years with liquid-based test.  At 30 is where you can do other things.  At 30, if you’ve had three normal tests in a row, you can spread out screening to every three years.

Also, the American Cancer Society says that if a woman has had normal screening throughout her life at least over the past 10 years, at age 70 she can stop screening.  And, obviously, if she’s had a total hysterectomy for a non-cancer cause, you don’t have to screen for cervical cancer.

The United States Preventive Services Task Force is very similar, start screening in women who have been sexually active, recommend against screening in women over the age of 65 – so they actually put the cut off five years earlier – and don’t screen if you had a hysterectomy for benign causes.  And the United States Task Force basically says they can’t tell you whether to use the liquid-based preps or the human papillomavirus testing.

Sexually Transmitted Disease Screening

The American College of Obstetrics and Gynecology says basically the same.  Between the ages of 20 and 30 you should have, you could be getting annual Pap smears or Pap smears every two years with liquid base, but at 30, you can start spreading them out.  And the American College of Obstetrics and Gynecology says that one of the things that you can do is check the Pap smear with the HPV screening and if both are negative, you don’t have to repeat until three years.

Now, of note, if this comes up on the board, this patient should also be screened routinely for Chlamydia.  Chlamydia has a grade A recommendation.  Obviously, if somebody is at risk for Chlamydia you should screen it.  But in all women under the age of 25, along with their Pap smear, they should be screened for Chlamydia.

What about other cancers?  Breast cancers, I think you’re well aware of, mammogram starting at the age of 40.  The only thing I will highlight here is that breast self-exam is now optional because we really have no data that it actually works.  The United States Task Force basically says the same thing.

Lung Cancer Screening

What about our number one killer – cancer, the lung cancer?  The United States Task Force has basically said, “We don’t have any evidence at this point in time to recommend screening for lung cancer with pet scans, chest x-rays or sputum.  You know, there’s a large clinical trial going on to answer this question, but the answer at this point in time is really “no screening.”

And there’s a whole other list of cancers that has recommended that you don’t screen for – ovarian cancer, bladder cancer, pancreatic cancer, and testicular cancer.

Vaccine Programs

So let’s shift gears and talk about shots.  You should know the basic facts.  What are the alive, attenuated virus vaccines such as MMR, varicella, what are dead virus vaccines such as influenza and the same that holds bacterial vaccinations?  Remember that HepA and HepB are recombinant vaccinations.

A general principle is that in immunosuppressed patients and pregnant patients, avoid live virus vaccines.  Shots that are okay to give in pregnancy is pneumococcal, HepB, tetanus shots.  And think about your special circumstances, you’ll probably get a question of a new HIV patient coming into your office and what immunizations do you need to give.

So, in this case here, you have a 49-year-old male with a history of irritable bowel syndrome.  He is on no medications but he does smoke.  He’s a homosexual but is in a long-term relationship and he knows recently that his HIV status is negative.  He’s thinking about working part time in a day care center, and he was told he should see his doctor because he needs some shots.  He thinks he’s had all his childhood immunizations, but he doesn’t bring records for you.  And he knows his last shot was about 15 years ago when he cut his hand on some wood.

Vaccine Practice Question

So what would you recommend for this gentleman?  Should he get:

A. tetanus shot;

B, an MMR;

C, a tetanus, HepA, HepB; or

D, all of them – tetanus, HepA, HepB, and MMR?

I would agree with the majority of you here that he should get C – tetanus, HepB and HepA.

Tetanus Vaccine

And let’s go through that.  Tetanus, very easy, recommendation is every 10 years.  His last tetanus was about 15 years ago – presumed.  This one is the one that sometimes can be a little tricky because you have to do a little math.  Basically, if you were born before 1957, you generally don’t need anything.  So if you did quick math – and being 49, he was born in 1956, and he doesn’t need to be vaccinated.  If you’re born after 1957, it’s generally recommended that you get one booster shot, unless you can document immunity, you can document that you had a disease or that you have a contraindication.

Rubella Vaccine

For people at high risk – and we fall into this – healthcare workers born after 1957, if your tithers are not positive, you need two shots.  Remember the special situation of women in child bearing years, you should always determine the rubella status because you’re concerned about congenital rubella syndrome and, if needed, since it’s a live attenuated vaccine, you can’t give it while she’s pregnant but you can easily give it postpartum.

Hepatitis Vaccine

HepA, there’s at risk individuals that you should immunize again, including homosexual men, (inaudible) vaccine.  And HepB – I think we’re all familiar with – recommended for all adolescents and adults at increased risk.  A booster is not recommended, if a question comes up about who should you check tithers on after you’ve given them three shots.  Healthcare workers such as ourselves and patients on hemodialysis, if the tither comes back negative, these people should be revaccinated with all three shots.  And this is the safe shot to give in pregnancy.

Vaccine Practice Question 2:

Next case.  So you have a 75-year-old guy with end-stage renal disease on hemodialysis.  He also has heart disease, hypertension, lipids and carotid disease.  He’s coming in to see you for routine follow-up.  It is now early November.  The patient had a flu shot two years ago but it made him sick and he is reluctant to take it again, but probably will if you recommend it.  He knows that his last Pneumovax was six years ago and his last tetanus he is sure was 20 years ago.  So would you recommend that this gentleman get a flu shot and a tetanus shot;

A pneumococcal vaccination

B tetanus shot

C, pneumococcal vaccination;

D, influenza and pneumococcal vaccination; or

E, all of them?

I would say, yes, they should have all of them.

Tetanus – we already talked about – although some organizations say that if you’ve been vaccinated at least once above 65, you don’t give any boosters.  So you don’t need a booster, but, again, the recommendation is still every 10 years.

The flu shot, the official recommendation is everybody over the age of 50 or anybody who has medical risk factors that would benefit from having the shot.  We should be vaccinated.  Household members of patients at risk should be vaccinated.  Pregnant women greater than 13 weeks gestation should be vaccinated.  And the only true contraindication is if you’re allergic to eggs.  It’s a dead virus vaccine, so it doesn’t make you sick – and people need to be reminded of that.  The only caveat to that is that the new intranasal vaccine is actually live, attenuated, and the nasal vaccine should not be given to pregnant or immunosuppressed patients.

Pneumococcal Vaccines

Pneumococcal vaccinations, 65 and above, or at risk patients, always a question of revaccination comes up, this is who you need to revaccinate.  One time revaccination after five years in patients with chronic renal failure on hemodialysis, which our patient was, somebody who doesn’t have a spleen or people who are immunosuppressed in general or, if you received your first pneumococcal vaccination before the age of 65, should have a booster in five years.  So, if you got it at 63, at 68 you would need a booster.  They don’t recommend boosters for routine people who have had the shot 65 years and older.

Vaccine Practice Question 3:

All of the following are true except for,

A, meningococcal vaccine is recommended for college freshmen;

B, varicella is recommended for women in the postpartum period if not immune;

C, meningococcal vaccine is recommended for patients with terminal complement deficiency;

D, varicella is recommended for all patients without a prior history of varicella; or

E, meningococcal vaccination is recommended for travelers to Mecca, Saudi Arabia, for the hash?  So we have a fairly wide spread here, the correct answer is actually D.

The second biggest answer was B – varicella is recommended for women in the postpartum period – so after they had given birth if not immuned.  Obviously since it’s a live attenuated vaccine, we don’t want to give it to a pregnant woman.

Varicella Vaccine

So, briefly, about varicella vaccination, as I already mentioned, is a live attenuated vaccine.  It’s recommended now for all children or adults who are at risk.  It’s a two-shot vaccination.  And studies have shown actually that you don’t vaccinate all adults – and that’s why D is the correct answer – because if you test somebody who says they haven’t had a history of chickenpox, up to 70 percent will have immunity.  So if you’re worried a 40-year-old comes into your office asking about the shot, check tithers first before you vaccinate.

Meningococcal Vaccine

The meningococcal vaccination is basically recommended in persons older than two years of age or considered at high risk, such as people with asplenia or complement deficiencies, travelers to the meningitis belt, which includes sub-Saharan Africa, into Saudi Arabia, and anybody who is going to be living in a college dorm-type setting, whether either the military or college freshmen.

Recommended Reading

So I know this was a lot to go over, but I’m going to lose my voice quick if I don’t stop.  I want to point out two good websites: www.immunize.org.  Basically, it will give you a table of all the immunizations and when they’re recommended and contraindications.  It’s very easy to download to your PDA and very easy to look at.

The second website is www.preventiveservices.ahrq.gov.  This is – it will give you the United States Task Force recommendations for all cancer screenings, letters or recommendation.

Obesity: The Next Frontier in the West

And my last slide before I quit, basically, one of the other big keys to prevention is don’t go McDonald’s or Burger King or wherever.  As you can see from this graph, we’re pretty much all red states now.  We’ve left all the blue states behind.  Pretty much, we are all on the overweight to obese side.

Leave a Comment