cbse equations

Question 1

filtration fraction

Answer 1

FF = GFR / RBF
GFR is about 120
RPF is about 600 (renal plasma flow)

in healthy FF is about 20% of RPF

Question 2

clearance

Answer 2

Cs + [urine concentration of S] x [urine flow rate] / [plasma concentration of S]

Question 3

GFR can be obtained by ?

RPF?

Answer 3

clearance of creatine

clearance of PAH

Question 4

absolute risk increase?

number needed to harm?

Answer 4

adverse event rate in control and experimental then subtract adverse in experimental from control

NNH = 1/ the absolute risk increase

Question 5

sensitivity

Answer 5

people with the disease that test positive

want this number high to know picking up on diagnosis
higher = better at ruling out disease
SCREENING diseases

A / A+C
true positive / true positive + flase negative

rule OUT disease

Question 6

specificity

Answer 6

true negative
without the disease who test negative

closer to 100 p = better at ruling in
low false positive
confirm after positive screen
SPIN

D/D+B
true negative/ true negative + false positive

Question 7

type 1 error

Answer 7

shows a relationship tht does not really exist

Question 8

type II error

Answer 8

study fails to show a relationship that does exist

beta error

Question 9

Vd=

Answer 9

amount of drug given (IV)/ [drug] plasma

low Vd = intravascular space and large/ charged molecules + bound

medium = intrvascualr and extracellular

large = able to get to all tissues and including fat
- usually small and lipophilic molecules

Question 10

clearance of a drug

Answer 10

0.7 X Vd/ t 1/2

Question 11

1/2 life =

Answer 11

.7 X Vd / clearance

Question 12

hardy weinberg equations

Answer 12

p+q=1
P^2 +2pq+q^2=1

p^2= frequency of homozygous for p

q^2 = freq for homozygous for q

2pq= frequency of heterygosity

Question 13

positive skew graph in terms of mean median and mode

negative?

Answer 13

shifted to the left
tail to the right

mean > median
median > mode

mode > median
median >mean

Question 14

case control study

Answer 14

w/ disease and w/out groups
then look back at it

look at some exposure risk

retrospetive and observational

purely observational
- no intervention

*used to identify risk factors for diseases

NOT causal -
yields an odds ratio!!

Question 15

odds ratio

study design and equation?

Answer 15

AxD divided by BxC

Question 16

cohort study

Answer 16

group of people that has something in common

compare them to group that have not had that exposure and then follow them

*purely observational
either retrospective or prospective

Question 17

formula associated with cohort study

Answer 17

relative risk

or risk ratio

Question 18

relative risk equation

Answer 18

A/A+B divided by C/C+D

Question 19

cross sectional study

Answer 19

looks at a population at a point in time
(ex dx of COPD at a time)
or ask about a risk factor
- exposed to 2nd hand smoke on that day

known as PREVALENCE

observational study

Question 20

what does cross sectional show

Answer 20

prevalence

Question 21

controlled clinical trial

Answer 21

investigator intervenes
so not purely observational - there is intervention

controlled = placebo and then an experimental group

Question 22

randomized

Answer 22

limit bias

Question 23

double blinded

Answer 23

particpant or investigator doesnt know who gets what

Question 24

meta analysis

Answer 24

combines data from many studies together

increase statistical power

quality depends on quality of individual studies

Question 25

true positive location

Answer 25

upper left (A)

Question 26

false positive location

Answer 26

upper right (B)

Question 27

false negative location

Answer 27

lower left (C)

Question 28

true positive location

Answer 28

lower right (D)

Question 29

sensitivity equation | + acronym

Answer 29

A/ A+C true positives divided by everyone who has the disease (true positives plus the false negatives) 1- the false negative PID - positive in disease

Question 30

specificity | + acronym

Answer 30

proportion without disease with a negative test results true negative / true negative plus false positives D/ (D+B) 1- false positive NIH acronym negative in health

Question 31

PPV | positive predictive value

Answer 31

A/ (A+B) true positives / everyone that tested positive

Question 32

NPV | negative predictive value

Answer 32

D/ (C+D)

Question 33

PPV change with increasing prevalence

Answer 33

PPV increases with increases in prevalence of disease so increase true positives and false negatives

Question 34

NPV change with increasing prevalence

Answer 34

increasing flase negatives | so decreasing the NPV

Question 35

low disease prevalence changes to PPV and NPV?

Answer 35

PPV decreases and NPV increases

Question 36

prevalence

Answer 36

of people with the disease / total population certain amount with disease at a certain time

Question 37

incidence

Answer 37

``` # of new cases diagnosed / total # of people at risk for that illness ``` people with the disease not used in this calculation

Question 38

low prevalence effect on relative risk and odds ration

Answer 38

in low prevalence situations | RR will EQUAL OR

Question 39

attributable risk equation

Answer 39

rlative risk equation but instead of dividing you subtract A/(A+B) - C/(C+D)

Question 40

absolute risk reduction

Answer 40

looks at how much an intervetnion will reduce risk of disease opposite attributable risk equation so C/(C+D) - A/(A+B)

Question 41

number needed to treat

Answer 41

1/ absolute risk reduction needed to treat to save a life or avoid a bad outcome

Question 42

Number needed to harm

Answer 42

1 divided by the attributable risk reduction which is A/(A+B) - C/(C+D) so 1 divided by that

Question 43

standard distribution curve / graph | % that fall within SD?

Answer 43

``` 68% fall within 1 SD (34% +/-) 95% fall within 2 SD (13.5% +/-) 99.7% fall within 3 SD (2.35% +/-) ``` then .15%

Question 44

small p value?

Answer 44

more likely to be | less than 0.05 - can reject null and shows an association

Question 45

standard error of the mean?

Answer 45

standard deviation divided by / square root sample size (n)

Question 46

confidence interval

Answer 46

range from [mean-Z(SEM)] to [mean+Z(SEM)] Z is specific to confidence interval

Question 47

Z in confidence interval if 90% CI? 95% CI? 99% CI?

Answer 47

90% CI = 1.645 95% CI =1.96 99% CI = 2.57

Question 48

if CI crosses 0?

Answer 48

accept null hypothesis

Question 49

chi ^2 vs t test

Answer 49

t test looks at the means chi-square looks at percentaes or proportions of categorical outcomes in 2 or more groups

Question 50

correlation coefficient that is perfect

Answer 50

``` 1= perfect 0= none ``` greater than 0 = positive correlation less than 0 = negative