Epidemiology Flashcards
Event rate in control group
Event rate experimental group
Absolute risk
Occurs because screening test are more likely to find slow growing tumors rather than those that are rapidly growing. This can bias in favor of screening because more slow growing cancers with a good prognosis will be found with a screening test
Lead time bias
Occurs because study volunteers and persons willing to undergo screening test are likely to be compliant. Compliant patients have better outcomes
Compliance bias
Occurs when two or more factors are associated with the outcome and only the one being studied is accounted for
Confounding bias
Occurs when subjects for the study do not represent the population. This is avoided by having large representative samples
Selection bias
This occurs when care provided to the experimental and the control group differ substantially other than the intervention. It is avoided by blinding. Patients and doctors tend to behave differently when they know they are being studied. Radiomized blinded trials protect against this bias
Performance bias
There is no consistent relationship between blood levels of morphine and analgesic effects. Thus no single right dose. You should titrate to desired effect. This is because of?
Tolerance
Hypothesis that a there is no significant difference between two groups being compared to each other Thus is the p value is less than 0.05 REJECT IT
Null hypothesis
When error occurs because too few are tested
Type 2 error
Calculate the median number
127,104,103, 81, 86, 117, 89, 97, 95
First rank the numbers: 81, 86,89, 95, 97, 103, 104, 117, 127 then add the total number +1 divided by 2 to identify
Median= 97
Calculate the mean?
81,86,89,95,97,103, 104,127,127
N=the total number included in data set n=9 81+86+89+95+97+103+104+117+127= 899 =899/n = 899/9 =99.89
Calculate mode
81, 86, 89, 95, 97, 103, 104, 117, 127
The mode of a sample of data is the observation that occurs most frequently
There is no unique mode since each number in data set is listed only once
The more cases you detect , the more false negatives will be included in your sample. Thus best screening test includes both both high sensitivity and high specificity
As sensivity increases specificity decreases
In study diabetic pts w no intense treatment had 10% neuropathy, diabetic pts with intense therapy had 2% neuropathy how many diabetic patients need to be treated with intense therapy to prevent neuropathy?
first test is for NTT
NTT= 1/ABSOLUTE RELATIVE RISK ARR= control group event rate - experimental group event rate ARR= 10-2%= 8% = .08 NTT=1/.08 =12.5
To prevent a disease from occurring at all by removing it’s cause
Primary prevention
