General Medicine Flashcards
What is the confidence interval
95% confidence interval indicates that the researcher can be 95% certain that the value expressed in a study truly lies within the interval.
What is the P value
P value less than .05 represents a low likelihood of it happening by chance. .05 is usually the cut off representing a 1 in 20 change of obtaining the observed results by chance
Prevalence (prev) equation
= (TP + FN)/(TP+FP+FN+TN)
the proportion of patients with the disease in the population
Sensitivity (Sn)
Sn = TP/ (TP+FN)
proportion of patients with the disease who have a positive test
Specificity (Sp)
= TP/ (FP+TN)
proportion of patients without the disease who have a negative test
Positive predictive value (PPV)
PPV= TP/(TP+FP)
Proportion of patient with a positive test who has the disease
Negative predictive value (NPV)
= TN/(TN+FN)
Proportion of patients with a negative test who do not have the disease
Positive likelihood ration (LR+)
LR+= Sn/ (1-Sp)
The ratio of positive test with disease to positive test without disease
Negative likelihood ratio (LR-)
= (1-Sn)/Sp
ratio of negative test in patients with the disease to those with negative test without disease
Pretest odds
= pretest probability /(1- pretest probability)
the odds that a patient has the disease before the test is performed
Posttest odds
= pretest odds x LR
The odds that a patient has the disease after a test is performed
Absolute risk (AR)
AR = patient with event in group/total patients in group
Number needed to treat
NNT = 1/ARR
Number of patients needed to receive a treatment for one additional patient to benefit
Number needed to harm (NNH)
= 1/ARI
Number of patients needed to receive a treatment for one additional patient to be harmed
(ARI= absolute risk increase)
Screening for lipid disorders
Recommended in all men 35 years of age and older
20-34 years old if risk factors for CVD, DM, family history of CVD, HTN, Tobacco, Obesity.
Women 20 and older if any of the above
- Screen every 5 years
