Biostatistics Flashcards

Question

Power is determined by....

Answer 1

number of outcome values collected, difference in outcome rates between groups and significance (alpha) lvl larger sample size = increases study power

Answer 2

ratio of risk in exposed group (txm) divided by risk in control group

Answer 3

number of subjects in group with an unfavorable event / total number of subjects in group

Answer 4

risk in txm group / risk in control group

Answer 5

RR =1 = no difference in risk of outcome between groups RR > 1 = greater risk of outcome in txm group RR < 1 = lower risk (reduced risk) of outcome in txm group

Answer 6

indicates how much the risk is reduced in the txm group compared to the control group 1 - Risk Ratio = RRR

Answer 7

XXXXX patients were 43% less likely to have YYYYY than placebo-treated patients

Answer 8

includes the reduction in risk and incidence rate of the outcome ARR = % risk in control group - % risk in txm group

Answer 9

12 out of every 100 patients will benefit from txm or For every 100 patients tx with XXX, 12 fever will have YYYYY

Answer 10

number of patients who need to be treated for a certain period of time for one patient to benefit 1/ ARR

Answer 11

For eery 9 pts who receive XXX, YYYY is prevented in 1 patient

Answer 12

number of patients need to be treated for one patient to experience harm same formula, 1/ ARR

Answer 13

1 patient will be harmed for every 90 patients treated with XXX instead of placebo

Answer 14

Case control studies use Odds ratio

Answer 15

Exposure/txm | Outcome present | Outcome Absent | -------------------------------------------------------------------------------- Present | A | B. | -------------------------------------------------------------------------------- Absent. |. C. |. D. | Formula = AD/ BC

Answer 16

XXXXXX is associated with 25% increased risk of YYYYYY

Answer 17

used in survival analysis instead of using "risk" Hazard rate is rate a which an unfavorable even occurs within a short period of time

Answer 18

Hazard rate of txm drop / HR rate of control group

Answer 19

OR/HR = 1 = event rate is same in txm/control arms, no advantage to txm OR/HR < 1 = event rate is lower in txm group than control OR/HR > 1 = event rate is higher in txm group than control

Answer 20

used when endpoint has continuous data and normal distributed when single sample group = one sample T test when single sample group used for pre/post measurement (pt serves as own control) = paired T test When study has 2 independent variables = student T-test

Answer 21

Used for continuous data when using continuous data with 3 or more samples or groups

Answer 22

Chi square test ie. Assessing difference in mortality between 2 groups or pain scores based on pain scale

Answer 23

technique used to determine if one variable changes or is related to another variable when independent causes dependent to increase = positive correlation when independent causes dependent to decrease = negative correlation doesn't prove causal relationships

Answer 24

used to describe relationship between a depends variable and one or more independent regression is common in observational studies where researchers need to assess multiple independent variables or need to control for many confounding factors

Answer 25

Sensitivity = how effectively test identifies pts with condition 100% sensitivity = test will be positive in all pts with condition Specificity = how effectively test identifies pts without condition 100% specificity = test will be negative in all pts without condition

Answer 26

(A / A + C) X 100 A = # that have condition w/ positive test result C = # that have condition w/ negative test result

Answer 27

( D / B + D) X 100 D = # without condition with a negative test result B = # without condition with a positive test result

Answer 28

include data for all pts original allocated to each txm group, even if the patient did not complete the trial according to study protocol

Answer 29

conducted for subset of trial population who completed the study according toe the protocol

Answer 30

attempt to demonstrate new txm has roughly same effect as old txm

Answer 31

attempt to demonstrate new txm is no worse than current standard based on predefined non-inferiority (delta) margin delta margin is minimal difference in effect btw 2 groups that is considered clinically acceptable based on previous research

Answer 32

often in meta-analysis, when multiple studies results are pooled into a single study

Answer 33

Info: compares pts with disease vs without, retrospective Benefits: data easy to get, less $$ than RCT, good for looking at outcomes in unethical interventions Limitations: cause and effect cant reliably by determined

Answer 34

Info: compares outcomes of group of pts exposed and not exposed to txm, follows prospectively Benefits: good for looking at outcomes when intervention would be unethical Limitations: more time consuming and $$$ than retrospective, can be influence by confounders (other factors that affect outcome)

Answer 35

Info: signe patient = report, few patients = series Benefit: Identify new diseases, drug SE or potential uses, can generate hypothesis for other studies Limitations: conclusions cant be drawn from single or few cases

Answer 36

Info: pts randomized and sometimes blinded to txm groups Benefit: Less potential bias, preferred study to determine cause/effect/ superity Limitations: $$$ and time consuming, hard to reflect real life scenarios

Answer 37

pts receive treatment A first, then switch to txm B and second group does opposite Benefit: act as own control, minimize confounders Limit: washout period req

Answer 38

Info: combines results from multiple studies to come to conclusion that has more statistical power Benefit: smaller studies can be pooled, instead of making large study Limit: studies may no be uniform in size/inclusion/exclusion etc

Answer 39

summary of clinical literature that focuses on specific topic or question Benefit: cheap, studies already exist

Answer 40

Drug prep, admin, etc Inpatient direct costs = hospital bed, staff, procedures etc Outpatient direct costs = office/clinic visits

Answer 41

traveling/lodging to hospital/clinic household costs like childcare, etc home health aides, etc

Answer 42

Lost work time Low work productivity morbidity, costs from having disease mortality = death

Answer 43

pain, suffering, anxiety etc

Answer 44

represents change in costs and outcomes when 2 txm alternatives are compared ex. Drug A $200, 5 txm success vs Drub B $300, 7txm success $300- $200 / 7 - 5 = $100/2 = $50 Drug B costs $50 more relative to Drug A for each additional txm success

Answer 45

used when 2 or more interventions have demonstrated equivalence in outcoems and the costs of each intervention are being compared

Answer 46

systemic process for calculating and comparing benefits of an intervention in terms of monetary units (dollars)

Answer 47

used to compare clinical effects of two or more interventions to the respective costs advantages = outcomes easier to quantify disadvantages = inability to directly compare different types of outcomes

Answer 48

specialized form of CEA that includes quality of life competent of morbidity assessments, usually use QALY and DALYs

Biostatistics Flashcards

(73 cards)