Biostatitics - Review Flashcards Preview

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Flashcards in Biostatitics - Review Deck (78):
1

Recall bias

results from inaccurate recall of past exposure
- applies mostly to retrospective control studies
- people who have suffered adverse effects are more likely to recall risk factors than those who don't

2

Referral bias

- ocurs when the case and control populations differ due to admission or referral pracrices

- example, study involving cancer risk performed at cancer research hospital may enroll cases referred all over the nation however, hospitalized control

3

Detection bias

refers to risk factor itself may itself may lead to intensive investigation and may increase probability of finding disease

- patients who smoke may undergo increased imaging due to smoking status

4

Lead time bias

occurs when screening test diagnoses a disease earlier than it would have appeared by natural history so time from diagnosis until death appears longer
- affected studies may not accurately reflect improvement in health

5

Allocation bias

results from how the treatment and control are assembled. May occur if subjects are assigned to study groups of clinical trial in a non-random fashion

6

Hawthorne effect

tendency of study population to affect outcome due to knowledge of being studies

7

Berkson's bias

selecting hospitalized patients as control group

8

Pygmalion effect

describes researcher's effect in the efficacy of treatment that can potentially affect outcome

9

Cystinuria

caused by defect in renal proximal tubules which result in decreased resorption of amino acid cysteine

- renal stones at young age
- hexagonal cystine crystals

10

Sodium cyanide nitroprusside tests

detects cystine's sulfhydryl groups
- turns purple

11

Primary oocytes

- developed by 5th month of gestation
- arrested in PROPHASE of meiosis I

12

Secondary oocytes

- arrested in METAPHASE of meosis II prior to fertilization

13

Sx: Simultaneous development of stroke, foot/intestinal ischemia and renal infarction. Likely diagnosis

Embolic phenomena
- often caused by left atrial clots, left ventricular clots, valvular vegetations, and aortic sclerotic plaques

14

Sx: Signs of renal failure (increased creatinine) and toe gangrene/livedo reticularis. Likely diagnosis?

Atheroembolic renal disease
- cholesterol emboli obstructs renal arterioles

15

Sx: Urinary hestinancy, urgency, frequency, incomplete coiding, post-void leakage in men > 60 years old.

BPH

16

Prostate

found between pubic symphysis and anal canal

17

Common causes of impetigo

S. aureus and Group A Strep

18

Post-streptococcal glomerulonephritis

- follows pharyngitis or skin infection (impetigo)

19

Conditions caused by incomplete obliteration of processus vaginalis

Hydrocele
Indirect inguinal canal

20

Hydrocele

- due to incomplete obliteration of processus vaginalis
- occurs when there is connection between scrotum and abdominal cavity that allows for leakage of fluid

21

Secretory phase of menstrual cycle

- occurs between ovulation and menses
- progesterone released by corpus luteum causes uterine glands to coil and secrete mucus-rich secretions and plumps up endometrium

22

In follicular phase, what hormone mediates endometrial proliferation?

Estrogen

- glands appear straight and narrow (small lumens)

23

In secretory phase, what hormone mediates endometrial proliferation

Progesterone
- glands appear dilated and coiled (wide lumens)

24

Best way to visualize T. pallidum

Darkfield microscopy

25

Cryptochordism

- undescended testes
- normal testosterone levels but low sperm (in adults)
- if uncorrected, seminiferous tubules atrophy and Sertoli cells secrete less inhibin
- increased risk of testicular cancer

26

Sertoli cells

- found in seminiferous tubules
- secrete INHIBIN - which inhibits FSH
- support sperm synthesis

27

Leydig cells

- secrete testosterone

28

Annovulation

-common in first five to seven years after menarche and last years before menophause
- manifests with marked menstrual in variability

29

FSH levels in menopause

Elevated FSH levels in menopause

30

Phenylepherine

alpha agonist with some selectivity for alpha 1 receptors
- would encourage urinary retention

31

Treatment for urinary retention

Muscarinic agent (bethanecol)
or alpha-blocking agents

32

Finasteride

- prescribed to patients urinary retention secondary to BPH
- 5-alpha reductase inhibitor which decreases DHT, which would decrease hypertrophy of bladder

33

Hydronephrosis

dilation of renal pelvis and calyces due to obstruction of urine flow
- kidney enlargement and distortion, compression of papillae, and thinning of parenchyma around calyces seen
- commonly caused by BPH

34

Treatment for patients presenting with calcium stones with hyperoxaluria

low sodium diets

35

Ectopic pregnancy

- higher occurence in patients with PID
- abdominal pain, vaginal bleeding, hemorrhagic shock, and amenorrhea
- biopsy shows decidual changes but no chorionic villi

36

Sildenafil

inhibitor of cGMP phosphodierase
- NO and ANP use this mechanism

37

Signs of urethral injury

- inability to void despite sensation of full bladder
- high riding boggy prostate
- blood in urethral meatus

38

Injury to posterior urethra

associated with pelvic fracture

39

Injury to anterior urethra

associate with straddle injuries

40

Hormones that prevent lactation during pregnancy

Estrogen and progesterone

41

B-lactamase inhibitors

Clavulanic acid
Sulbactam
Tazobactam

** extend the spectrum of penicilin binding antibiotics by decreasing their destruction

42

Tazobactam-Piperacillin

- Tazobactam - B-lactamase inhibitor allows piperacillin to act on gram negative bacteria that would not be vulnerable to piperacillin alone

43

BPH

- epithelial and stromal hyperplasia, mostly in periurethral and transitional zones
- urinary retention as a result leads to increased pressure in urinary tract, nephropathy, and hydronephrosis

44

Organs that drain to superficial inguinal lymph nodes

- all skin from umbilicus down (up to pectinate line) drains to superficial inguinal lymph nodes

45

Testicular hydrocele

- when serous fluid accumulates in tunica vaginalis
- results when processus vaginalis fails to close

46

Contraindications to OCPs

- Prior embolic event (stroke, PE, MI)
- History of estrogen dependent tumor
- Women over 35 who smoke
- Hypertriglyceridemia
- Liver disease
- Pregnancy

47

Gram-negative sepsis is caused by which bacterial factor?

LPS
- it is NOT secreted by bacteria but part of outer membrane
- induces activation of macrophages leading to IL-1 and TNF-alpa

48

Signs of septic shock

Fever
hypotension
Diarrhea
Oliguria
Vascular compromise
DIC

49

TNF-alpha

cytokines that induces systemic inflammatory response
- causes septic shock

50

Cytokines responsible for inducing systemic inflammatory response

IL-1
IL-6
TNF-alpha

51

Which mechanism does mifepristone use to terminate early pregnancy

Anti-progestin

52

Endometrial cells undergo what process upon withdrawal of progesterone

Apoptosis

53

Calcium oxalate/ calcium phosphate

- radiopaque
- octahedron
- most common

54

Magnesium struvite

- radiopaque
- resemble coffin lids (retangular prism)

55

Uric acid

- RADIOLUCENT
- yellow/red-brown diamond/rhombus

56

Cysteine

- Radiopaque
- hexagonal
- least common

57

Vasectomy

- transection of vas deferens
- has no effect on sperm proximal to ligation
- patients may still have viable sperm 3 months and at least 20 ejaculations

58

Pathogenesis of acute pyelonephritis

- vesicoureteral reflux

59

Pathogenesis of lower UTIs

- suppression of indigenous flora
- colonization of distal urethra by gram - rods
- attachment of gram - pathodesnt to bladder mucosa

60

Sx: Adnexal mass in elderly female

- Likely ovarian malignancy

61

Serum marker for recurrence of ovarian malignancy

CA-125

62

Sx: fever, maculopapular rash and symptoms of ARF, 1-3 week after beginning treatment with B-lactam antibiotic

suggests interstitial neprhitis
- peripheral eosinophilia and eosinophiluria
- symptoms will stop after cessation of medication

63

Serum and urine levels associated with calcium kidney stone

- Normocalcemia
- Hypercalciuriae

64

Standard treatment for N. gonorrthoae

- Ceftriaxone ( for the N. gonorrohoe) + Doxycycline or Azithromycin for possible co-infection of C. trachimatis

65

Mechanism of OCPs

- doses of estrogen and progesterone
decrease synthesis of FSH and LH in anterior pituitary thus decreasing gonadotropin levels

66

Type I error

when researchers reject a TRUE null hypothesis

b/b+d (kind of like specificity)

Alpha - probability of making a type 1 error, typtically set at p = 0.05

67

Type II

when researchers accept a FALSE null hypothesis

c/a+c - (kind of like sensitivity)

B - probability of commiting type 2 error

68

Alpha (in terms of biostatistics)

maximum probability of committing a type I error

typically accepting p = 0.05

69

Beta ( in terms of biostatistics)

maximum probability of committing a type II error (accepting a false null hypothesis)

70

Power

(1 - Beta)
probability of rejecting a null hypothesis when it is truly false

71

Observer Bias

to prevent patient or researcher expectancy from interfering with determining outcome
- often prevented by blinding patients OR both patients and physicians from the groups

72

Selection bias

results from manner in which people are selected for the study, or from the selective losses from follow-up

73

Odds Ratio

ad/bc

74

Relative Risk

a/(a+b) - c/(c+d)

75

Prospective cohort study

initially a group of subjects is selected and their exposure status is determined. The cohort is then followed for a certain amount of time and observed for development of outcome

76

Retrospective cohort study

exposure status is determied retrospectively and then that person is tracked from that point of time, using medical records

77

Cross sectional study

simultaneous measure of exposure and outcome
- uses surveys

78

Case control

selecting patients with particular disease (cases) and with that disease (controls) and then determining exposure status