statistics

Question 1

highly sensitive test is useful for what?

Answer 1

SNOUT: rule out

helps for screening purposes, as it negative results on these tests will help rule out diagnosis

Question 2

what is a likelihood ratio?

Answer 2

probability of a given test result occurring in a patient with a disorder compared to a probability of the same result occurring in a patient without the disorder

• does NOT change with prevalence of the disease
• useful for >2 different studies
• positive LR: sensitivity/ (1- specificity)
• negative LR: (1-sensitivity)/ specificity

Question 3

sensitivity vs specificity

Answer 3

• sensitivity: TP/ (TP+FN)

- specificity: TN/ (TN+FP)

Question 4

PPV vs NPV

Answer 4

• DOES depend on disease prevalence
• PPV: (TP/TP+FP)
• NPV: (TN/TN+FN)

Question 5

which studies use odds ratio?

Answer 5

• case control studies–> exposure of participants with the disease vs exposure of participants without the disease

Question 6

which studies use relative risk?

Answer 6

cohort studies

Question 7

attributable risk percent

Answer 7

risk of exposed- risk of unexposed/ risk of exposed

Question 8

What is the basic premise for intention to treat analysis

Answer 8

Randomization

Blinding

Question 9

What is a type II error and what is its relation with sample size and power?

Answer 9

Occurs when the alternative hypothesis is rejected but is actually true

Power and sample size increase will decrease type II error

Question 10

What is a measurement bias?

Answer 10

Poor data collection leads to inaccurate results, usually not seen in randomized clinical trials

Question 11

Calculating number needed to treat

Answer 11

1/ARR

1/risk of control-risk of case

Question 12

define standardized mortality ratio

Answer 12

observed n of death/ expected n of death
adjusted measure of overall mortality
used in occupational epidemiology

Question 13

What is a factorial study design?

Answer 13

experimental study design with 2 or more interventions and all combinations of intervention

Question 14

what is length time bias?

Answer 14

when survival benefits of a screening tests are overstated due to including lots of benign slow progressing cases

Question 15

What does external validity measure?

Answer 15

generalizability of the study to other populations

Question 16

Initial evaluation tests for lead poisoning includes what?

Answer 16

CBC, serum iron and ferritin levels, and reticulocytes

Question 17

Treatment of rosacea (erythema in central face associated with flushing, telangiectasias, pustules, recurrent chalazions)

Answer 17

topical metronidazole

- would need ophtho consult

Question 18

Best initial test for polycythemia (elevated hemoglobin/hematocrit)

Answer 18

erythropoietin level test— low is polycythemia vera, high is chronic hypoxia

Question 19

erbs palsy serious complication, prognosis

Answer 19

diaphragmatic paralysis due to phrenic nerve involvement

- prognosis: good, 80% chance to full recovery

Question 20

schizoaffective disorder ddx

Answer 20

psychosis without mood sx lasting for at least 2 weeks, with major mood episode concurrent w/ sx of schizophrenia

Question 21

Hypertension after kidney transplant is caused by what? what lab values will change after using ace inhibitors?

Answer 21

• renal artery stenosis

- creatinine will increase after starting ace-i if ddx is renal artery stenosis

Question 22

Parkinson’s disease (bradykinesia, resting tremor, rigidity) initial treatment

Answer 22

levodopa
dopaminergic agonists (pramipexole, bromocriptine)

Question 23

Lab and image findings of Paget’s disease, diagnosis, treatment

Answer 23

• elevated serum and bone specific ALP
• calcium and phosphorus usually normal, elevated with fracture/immobilization
• lytic lesions or mixed on plain radiograph
• ddx: combo of radiographic findings and increased ALP, bone scan is more sensitive than x-ray
• tx: bisphosphonate

Question 24

Good lab test to order for diagnosing chronic kidney disease when creatinine is elevated? Tx?

Answer 24

• urine protein levels

- Ace-i or ARBs for proteinuria

Question 25

HIV patients with odynophagia, giant ulcers with no virus. Ddx and tx?

Answer 25

Aphthous ulcer

Prednisone

Question 26

Clinical fx of thyrotoxicosis, elevated T3 and T4 and elevated TSH and serum alpha units leads to what ddx?

Answer 26

TSH secreting pituitary adenoma

Question 27

Chronic prostatitis treatment

Answer 27

• first line: fluoroquinolones– cipro or levo

- second line: TMP-SMX

Question 28

Massive pulmonary embolism can cause pulmonary hypertension. What would the ECHO show?

Answer 28

• RV strain

- tricuspid issues

Question 29

Management of acute aortic dissection

Answer 29

• pain control with morphine
• IV beta blocker for target systolic bp of 100-120 to decrease left ventricular contractility
• if not well controlled, add nitroprusside

Question 30

Management of unstable angina in high risk patients

Answer 30

• coronary angiography then PCI/CABG if needed

Question 31

Septic embolism usually results from septic thrombophlebitis (painful subcutaneous mass in right cubital area). Best next step in management?

Answer 31

• obtain blood cx and start abx