Please enable JavaScript.
Coggle requires JavaScript to display documents.
equation/diagnostic test evaluation - Coggle Diagram
equation/diagnostic test evaluation
introduction
diagnostic assays assess disease presence/absence
statistical measures determine test performance
important for screening and confirmation
equations
sensitivity
TP ÷ (TP + FN) x 100
A ÷ (A + C) × 100
specificity
TN ÷ (TN + FP) × 100
D ÷ (D + B) × 100
PPV
TP ÷ (TP + FP) × 100
A ÷ (A + B) × 100
NPV
TN ÷ (TN + FN) × 100
D ÷ (D + C) × 100
letters
B
false +ve
C
false -ve
A
true +ve
D
true -ve
definitions
sensitivity
ability to identify true +ve
high sensitivity = fewer false -ve
specificity
ability to identify true -ve
high specificity = fewer false +ve
PPV
probability +ve result is truly +ve
NPV
probability -ve result is truly -ve
interpretation section
high sensitivity
useful for screening
minimises missed disease
high specificity
useful for confirmation
minimises false positives
high PPV
positive results reliable
high NPV
negative results reliable
conclusion
sensitivity/specificity essential in evaluating assays
best test depends on clinical context
screening prioritises sensitivity, confirmation prioritises specificity
evaluation
screening tests
prioritise sensitivity
accept more false +ve
confirmatory tests
prioritise specificity
trade-off discussion
no test perfect
balance depends on clinical purpose
clinical implications
false -ves may delay treatment
false +ves may cause anxiety/unnecessary testing