SPADA

Clinical Diagnostic Performance Related to

Disease Prevalence: Test Parameters

•

Sensitivity:

– the ability to identify as positive all those with the disease

•

Specificity:

– the ability to identify as negative all those without the disease

•

Predictive value positive (PV+):

– the proportion of true positives among those testing positive

•

Predictive value negative (PV-):

– the proportion of true negatives among those testing negative

Disease

Clinical Diagnostic Performance Related to Disease

Prevalence: Test Parameters

present

absent

a=true

positives

b=false

positives

c=false

d=true

Test

result

POS

NEG

total

a+b

PV+ = a/ (a+b)

PV- = d/ (c+d)

negatives

c+d

TOT

a+c

b+d

Sensitivity = a/ (a+c)

Specificity = d/ (b+d)