Epidemiology Flashcards
A patient asks you about a drug she saw advertised to treat her diagnosis. A recent journal article studied to treat her diagnosis. A recent journal article studied the drug’s effect and reported Number Needed to Treat (NNT) of 24. You tell your patient:
- 24 patients in the trial benefited from the drug
- You have 24% change of benefiting from the drug
- 24 individuals with characteristics like those in the trial would need to be treated with this drug for one individual to benefit
- The absolute risk reduction is smaller compared to the relative risk reduction
- 24 individuals with characteristics like those in the trial would need to be treated with this drug for one individual to benefit
Lower the NNT, the more effective the drug
A randomized controlled trial is conducted to compare a new drug to placebo in preventing a clinical outcome (progression of a disease). The results are as follows: relative risk of disease progression on the drug is 0.80; 95% confidence interval 0.65-0.98. Your conclusion is:
- The result is significant, demonstrating that the drug is effective
- This drug is completely ineffective
- You cannot determine the effectiveness without a number needed to treat (NNT)
- The confidence interval to too broad to be useful
- The result is significant, demonstrating that the drug is effective
0.80 is the relative risk, it’s a ratio, if it’s < 1 it means the risk is less for that treatment group
if the number was 1 it means there is no effective
Always want this number to be on either side of 1
Range of possible values of the risk 0.65-0.98 you do not want the interval to cross 1 that means the
treatment had no impact. If it contains is = 1 it is not statistically significant
Rank the following trial types from most robust to least robust for clinical use:
a. Meta analysis
b. Case report
c. Randomized controlled trial
d. Cohort study
C, A, D, B or A, C, D, B
A test with high sensitivity may:
- Have a high false positive rate
- Detect 99% of individuals with the condition
- Have a high false negative rate
- Have a low specificity
- Have a high false positive rate
- Detect 99% of individuals with the condition
- Have a low specificity
Treating postmenopausal women with estrogen plus progestin will:
a. Decrease the risk of coronary artery disease
b. Decrease the risk of a bone fracture
c. Decrease the risk of blood clot
d. Decrease the risk of breast cancer
b. Decrease the risk of a bone fracture
A, C, D all increase risk
Which of the following is NOT TRUE about valacyclovir?
a. It is indicated to treat genital herpes simplex outbreak (HSV-2 outbreaks)
b. It is indicated to decrease the risk of HSV-2 transmission from an affected person to an unaffected person
c. It is indicated for treatment of seronegative people (without HSV-2 antibodies) to prevent HSV-2 infection
d. Is reliably prevents all HSV-2 transmission when used as indicated
c. It is indicated for treatment of seronegative people (without HSV-2 antibodies) to prevent HSV-2 infection
d. Is reliably prevents all HSV-2 transmission when used as indicated
Evaluation to lower the risk of death from cancer may involve which of the following:
a. Screening for early cancer
b. Screening for precancerous lesions
c. Screening for genetic predisposition to cancer (only for high risk individual)
d. Assessing cancer risk factors
All options
Which of the following is true regarding cancer screening?
a. As cancer risk increases in a population, the likelihood that an abnormal finding one exam or testing is due to cancer increases
b. A positive screening test can be used to confirm a cancer diagnosis
c. Discussion around screening should stay focused on testing and not cover cancer prevention strategies
a. As cancer risk increases in a population, the likelihood that an abnormal finding one exam or testing is due to cancer increases
Which of the following is true for a cancer with lead time bias?
a. Early diagnosis is generally effective at decreasing mortality
b. Delayed diagnosis is unlikely to have much impact on the long term outcome
c. Sensitive screening tools exist
d. Slow-growing
b. Delayed diagnosis is unlikely to have much impact on the long term outcome
c. Sensitive screening tools exist
Which of the following is true for a cancer with length time bias?
a. Early diagnosis is generally effective at decreasing mortality
b. Delayed diagnosis is unlikely to have much impact on long term outcome
c. Sensitive screening tools exist
d. Slow-growing
b. Delayed diagnosis is unlikely to have much impact on long term outcome
c. Sensitive screening tools exist
d. Slow-growing
A 45 year old female asks her PCP about breast cancer screening
during a routine physical.
Medical history: High cholesterol
Medications: Simvastatin, calcium
Family history: Mother alive, age 75, breast CA Dx age 65 and treated, father alive, age 78, CAD (s/p MI), sister
and well age 48
Social History: no smoking; 2 glasses of wine per day; no drug use, married to male partner, 2 kids ages 18 and 15
Which of the following factors does not increase her risk of breast cancer?
a. Increasing age
b. Family history of breast cancer
c. Alcohol consumption
d. Childbirth before age 30
d. Childbirth before age 30
A 45 year old female asks her PCP about breast cancer screening
during a routine physical.
Medical history: High cholesterol
Medications: Simvastatin, calcium
Family history: Mother alive, age 75, breast CA Dx age 65 and treated, father alive, age 78, CAD (s/p MI), sister
and well age 48
Social History: no smoking; 2 glasses of wine per day; no drug use, married to male partner, 2
kids ages 18 and 15
You tell her:
a. At her age, mammograms have repeatedly been shown to offer statistically significant
decreases in the risk for breast cancer death
b. Breast MRI is a good option for breast cancer screening
c. Genetic testing is good option for any woman concerned about breast cancer risk
d. It is important for every woman to make an individual decision based upon personal risks and
benefits
a. At her age, mammograms have repeatedly been shown to offer statistically significant decreases in the risk for breast cancer death
d. It is important for every woman to make an individual decision based upon personal risks and benefits
MRI’s are not generally used for an average risk patient since its very expensive, usually more used for high
risk individuals
A 45 year old female asks her PCP about breast cancer screening
during a routine physical.
Medical history: High cholesterol
Medications: Simvastatin, calcium
Family history: Mother alive, age 75, breast CA Dx age 65 and treated, father alive, age 78, CAD (s/p MI), sister
and well age 48
Social History: no smoking; 2 glasses of wine per day; no drug use, married to male partner, 2
kids ages 18 and 15
How would you advise this patient?
a. Perform breast self-exam (BSE) regularly because that is proven to increase rates of early breast
cancer detection and cure
b. There is no question that you should have annual mammography to decrease your risk of breast
cancer death with little risk of false positive
c. Consider BSE and mammography, but be aware that both have fairly high false-positive rates at your age
c. Consider BSE and mammography, but be aware that both have fairly high false-positive rates at your age
A 75 year old male is found to have an elevated PSA test on screening. Prostate exam shows moderate,
symmetrical gland enlargement. He reports waking up once or twice a night to void. Studies of prostate cancer
screening indicate:
a. PSA-detected prostate cancer death rates increase as men get older (especially above 70)
b. PSA screening for prostate cancer is a meaningful health screening in all men over age 50
c. PSA screening can detect early prostate cancer, but it is unclear whether intervening
on these PSA detected cancer will decrease overall mortality
c. PSA screening can detect early prostate cancer, but it is unclear whether intervening on these PSA detected cancer will decrease overall mortality
A 75 year old male is found to have an elevated PSA test on screening. Prostate exam shows moderate,
symmetrical gland enlargement. He reports waking up once or twice a night to void.
At this point, you should do the following:
a. Diagnose prostate cancer based upon the elevated PSA level
b. Conduct imaging studies (e.g. CT scan) and if findings are consistent with prostate cancer you can confirm the diagnosis and begin treatment
c. Obtain tissue (i.e. biopsy) before you can make a diagnosis of prostate cancer
c. Obtain tissue (i.e. biopsy) before you can make a diagnosis of prostate cancer
A 75 year old male is found to have an elevated PSA test on screening. Prostate exam shows moderate,
symmetrical gland enlargement. He reports waking up once or twice a night to void.
A prostate biopsy is performed and he is found to have prostate cancer. Additional evaluation reveals the
cancer is likely localized to the prostate gland. After an appointment with multi-disciplinary team, the patient is left
to decide between 3 options. How would you advise him?
a. Watchful waiting
b. Prostate surgery
c. Prostate radiation therapy
a. Watchful waiting
Prostate cancer is associated with which of the following:
a. Lead time bias
b. High false positive rate on screening
c. Aggressive tumors that rapidly progress to death
b. High false positive rate on screening
An 18-year-old female presents for a physical exam at her college health department. Which of the
following should be discussed regarding cervical cancer?
a. She is due for a pap test regardless of history
b. She should have a pap test only if at risk for HPV
c. Gardisil (HPV vaccination) cannot be offered to protect against HPV due to her age
d. A pap test is not indicated due to age
d. A pap test is not indicated due to age
Cervical cancer:
a. Is on the rise
b. Is often caused by a viral infection
c. Can only be detected in advanced stages
d. Is potentially vaccine preventable
e. Risk is increased with HIV infection
b. Is often caused by a viral infection
d. Is potentially vaccine preventable
e. Risk is increased with HIV infection
A 20-year-old male feels a testicular lump and presents for evaluation. What is the next step?
a. Check a PSA test
b. Remove the lump surgically
c. Perform an ultrasound for further evaluation
c. Perform an ultrasound for further evaluation
Smoking cessation counseling is provided, but the patient replies that he is too old for any impact from smoking cessation. You tell him:
a. He is right, but your clinical medicine professor suggested that you do so anyway
b. In as little as one-years time, his risk of coronary artery disease will fall by 50%
c. After stopping, his lung cancer risk wont change but at least it won’t increase as it would if he
continued to smoke
b. In as little as one-years time, his risk of coronary artery disease will fall by 50%
A 50-year-old woman presents for a physical examination. She is feeling well and takes no medications.
Family history is negative for cancers in first degree relatives. She asks about colorectal cancer screening.
Regarding colorectal screening:
a. Colonoscopy is the only currently recommended method
b. Several options are available and should be selected based upon the individual’s risk profile and preferences
c. Techniques available today can only detect cancer once it has developed
d. Has not been shown to impact mortality
e. You advise her against colorectal cancer screening
b. Several options are available and should be selected based upon the individual’s risk profile and preferences
Breast Cancer Screening Methods:
Mammogram
• MRI
• Breast exams
o Clinical breast exam (CBE)
o Breast self exam (BSE)
Confidence interval
Gives the range of expected values if the study was repeated many times, with X%
confidence (usually 95% or 99%)
o A result is significant if its confidence interval DOES NOT cross 1.0 (treatment
group/control group)
- Relative risk ratio, absolute risk ratio, odds ratio, hazard ratio
- If the value is 1, that means there is no difference between treatment and control groups,
greater than 1 increased risk
o Example: AREDS1
“Single-arm comparisons with placebo found risk reduction statistically significant for
antioxidant plus zinc…but not for the antioxidants arm (antioxidants: OR, 0.8; 99% CI,
0.59-1.09…; antioxidants plus zinc: OR, 0.75; 99% CI, 0.52-0.98)”
P-value
o Probability the result is due to change alone
o A result is significant if it is associated with p-value of p<0.05 (p<0.001 is even more significant!)
o If it was close to 0.05, can refer to it as a trend
o Example: OHTS
“At 60 months, the cumulative probability of developing POAG was 4.4% in the medication
group and 9.5% in the observation group (P<0.001)”
Relative Risk (RR) and Absolute risk (AR)
Relative Risk (RR)
o Risk reduction (or increase) of treatment relative to no treatment
o RR= % treated with disease / % untreated with disease
• Absolute risk (AR)
o Risk reduction (or increase) of treatment relative to baseline risk of disease
o AR = % untreated with disease - % treated with disease
• Example: OHTS study
o Relative risk reduction at 60 months = 4.4%/9.5%= 46%
o Absolute risk reduction at 60 months = 9.5%-4.4%= 5.1%
Sensitivity vs Specificity
Sensitivity
Likelihood your test will be (+) for a person with disease
- Sensitive test = high FP, low FN
- “SensiTive to the Truth” (i.e. get a positive test
result and have the disease)
Specificity
likelihood your test will be (-) for a person without
disease
- specific test= low FP, high FN
- “SpeciFies the False” (i.e. do not have a
positive test result and do not have the disease)
A test with a high sensitivity may:
have a high false positive rate
Detect 99% of people with the condition
Have low specificity
Results to Risks and Benefits of Estrogen Plus Progestin study
- Effect on estrogen + progestin on CHD and breast cancer in post-menopausal women
- Previous, smaller case-control studies + animal studies suggested a benefit
- This trial—16,608 post-menopasual women of all SEC (META-ANALYSIS
- After 5.2 years the trial was STOPPED due to INCREASED RISK OF BREAST CANCER + others
Results to Once Daily Valacyclovir to Reduce the Risk of Transmission of Genital Herpes study
• Decrease the risk of either HSV-1 or HSV-2 infection to susceptible partners: Hazard ratio for those
whose source partner was taking valacyvlovir as compared with placebo 0.45 (55% risk reduction)
(95% confidence interval, 0.24 to 0.84; P=0.01)
• Decrease in symptoms of genital HSV-2 infection among susceptible partners: Hazard ratio for those
source partner was taking valacyclovir 0.25 (75% risk reduction)
(95% CI, 0.08 to 0.75; P- 0.008)
• Decrease in virus shedding in HSV+ partner
• Decrease in viral load in HSV+ partner
Lead time bias-
earlier detection of fatal disease
does not improve mortality
• Earlier detection may lead to the
false impression that survival is
increased by screening
• Aggressive cancer (lung, pancreatic)
Length time Bias
earlier detection of a disease that
will probably not lead to the patients’ mortality
• Earlier detection may lead to diagnostic
procedures/treatments that carry risk of
adverse effects and cause undue stress
• Slow-growing, less aggressive cancer (prostate)
Breast Cancer
Risk Factors
• Age
• Family history
o One first degree relative risk 2x
o Two first degree relatives 5x
• Prior breast cancer
• Late pregnancy, nulliparity are risk factors
o Pregnancy is protective (especially before 30)
• Prolonged estrogen/progestin exposure
o Early menarche
o Later menopause
o Postmenopausal HRT
• Chest irradiation
• DES exposure
• Alcohol intake > 1 drink/day
• Overweight/obesity
• Physical inactivity
Breast cancer screening ages
Px chief complaint: Double vision & droopy eyelid
History:63 year old female presented at clinic after three months of gradually progressive double vision and droopy eyelid. She had binocular oblique diplopia, worse when looking to right. Symptoms where constant and didn’t fluctuate during day and activity. No difficulty swallowing, weakness, shortness of breath or trauma.
Ocular history: Wears glasses, no ocular surgery, trauma
Medications: None
Medical history: None
Family history: father died of oesophageal cancer
Social history: 60 pack year history, quit at 44. Worked in factory.
Prostate Cancer Screening
Methods:
o Prostate-specific antigen (PSA) – blood test
o Digital rectal exam (DRE)
USPSTF
Individualized decision for ages 55-69
No evidence for/against screening past age 70
American Urological Society
NO screening ages 40-54
Individual decision age 55-69, every 2+ years
NO screening age 70+ or if life expectancy <10y
Cervical Cancer Screening
Methods:
o Papanicolaou (Pap) test (cytology)
o Human papilloma virus (HPV) test (DNA)- blood test
American College of OB-CYNs (ACS)
Start screening at age 25, stop screening at age 65
Pap cytology + HPV every 5 years
OR
Pap cytology ever 3 years
Testicular Cancer (FYI)
• Most common cancer in males age 15-34 but only 10% of cancer deaths
• Treatable—95% survival at 5 years w/early detection/treatment
• USPSTF (2011)—no screening is recommended
• ACS (2015)—“testicular exam as part of routine cancer-related checkup” no formal recommendation on
monthly self-testicular exam
• Men with new lump are encouraged to seek medical attention
Screening is not recommended on daily basis
Lung Cancer Screening
• Risk based on “Pack-Years” of smoking
o 1 pack-year = 1 pack of cigarettes (20 cigs) every day for 1 year
= 2 packs of cigarettes every day for 1⁄2 year
= 1⁄2 pack of cigarettes every day for 2 years
o Methods:
chest X-ray (CXR)
Low- dose computed tomography (LDCT)
American Cancer Society
Annual screening with LD-CT for: age 55-74 with 30+ PYS history as current smoker or quit < 15 years ago
Patient in good health; no signs of sx of lung cancer
Smoking cessation counseling and informed decision-making
Risks exceed benefits in screening for low risk younger populations
*Insurance also may not cover low risk populations for screening
dose dependent risk- the more you smoke the more risk
Smoking Cessation
• Importance of quitting
o despite reducing smoking by 50%, rates of MI remain closer to heavy smokers
• Smokers who quit by age 35 have preserved longevity
• Additional benefits to smoking cessation:
o At 1 year, CAD risk falls 50%
o At 15 years, CAD risk is similar to non-smokers
o At 10 years, lung cancer risk falls to almost half vs. continuing to smoke
83 WM reffered for decreased vision in the left eye x 10 days
ROS - (+)night sweats, (+) weight loss over past 6 months, (+) dyspnea(shortness of breath)
Has smoked 1ppd x 60 years
No history of cancer
Deep lesions seen infiltrating both eyes at same time affecting macula, metastatic lung cancer to the choroid
• choroid is the most common location of cancer metastasis to the eye (when it occurs—overall, rare
event)
• Breast and lung are the most common cancer types to metastasize to the eye
• Bilateral, white or yellow multifocal deep lesions
64 Woman walsks into clinicDec 2014
CC: Blurry,double vision and imbalance x 2 weeks. Constant
PMH: NSCLC s/p chemoradiation Dec 2013, renal cell carcinoma s/p partial resection Aug 2013
VA: OD 20/50
OS 20/30 (previously 20/20 both)
Normal eye health anterior and posterior
NEW incomitant hypertropia
NEW horizontal jerk nystagmus in all gazes including primary gaze, worsening significantly on R gaze
Concern for cerebellar and/or brainstem stroke or metastasis (lung CA versus renal CA)
Pt has metastatic lung cancer that metastasized to the cerebellum
Colorectal Cancer Screening
• Methods
o Fecal testing
Fecal occult blood test (FOBT)
Fecal immunochemical test (FIT)
Fecal DNA test
o Imaging
Colonoscopy
Sigmoidoscopy (FSIG)
Barium enema x-ray
CT colonography (“Virtual colonoscopy”)
“Bear-tracking” (grouped CHRPE) is associated with FAP
o most common extra-colonic manifestation (up to 90%)
o Specificity: 95-100%/ Sensitivity: 54-85% depending on study
o Location, size, shape, degree of pigmentation can vary
o Be suspicious when lesions are multiple & bilateral
> or equal to 4 or 2 with one being large—68% sensitivity, 100% specificity
FAP associated CHRPE lesions:
- Bilateral
- Occurence in multiple quadrants
- Pisiform shape (most specific finding)
- Irregular borders
11 year old colombian female
MHx:
(+) FAP confirmed by genetic testing 3/2019 after developing 2 primary invasive colon cancers with significant colon polyps no s/p adjuvant chemo and currently on immunotherapy
(+) Medulloblastoma (8/2020) s/p craniospinal radiation and chemotherapy. Complicated by severe posterior fossa syndrome - remission with persisting endocrine (growth hormone and thyroid supplementation needed) and cognitive complications
Wilms Tumor
o Renal tumor in children
o WAGR Syndrome , Wilms tumor, aniridia, genitourinary (GU) anomalies and intellectual disability
§ Children have constitutional chromosomal deletion of the WT1 gene
§ Greater than 20% risk of developing Wilms tumor
“Bear-tracking” (grouped CHRPE) is associated with FAP
o most common extra-colonic manifestation (up to 90%)
o Specificity: 95-100%/ Sensitivity: 54-85% depending on study
o Location, size, shape, degree of pigmentation can vary
o Be suspicious when lesions are multiple & bilateral
> or equal to 4 or 2 with one being large—68% sensitivity, 100% specificity
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