Table 1.

Characteristics of the optimal EC detection tool.

Considerations	Definition	Formula	Implications in EC	Ideal EC diagnostic test criteria
Sensitivity	Probability that a person with a disease will test positive	TP TP + FN	A low sensitivity would mean a large proportion of women with EC will be falsely re-assured leading to delayed presentation (the false negatives who will later present at an advanced stage) and poor survival.	Maximal sensitivity (100%)
Specificity	Probability that a person without a disease will test negative	TN TN + FP	A low specificity would mean a large proportion of women without EC will undergo further unnecessary & invasive tests/treatments. The worried well population also increases.	Maximal specificity (100%)
Positive predictive value (PPV)	Probability that a positive test will correctly identify those with the disease	TP TP + FP	A low PPV has implications for women with a positive test, a large proportion of whom will undergo further unnecessary diagnostic tests or even treatments that are not indicated.	Maximal PPV (100%)
Negative predictive value (NPV)	Probability that a negative test will correctly identify those without the disease	TN TN + FN	A low NPV has implications for women with a negative test, a large proportion of whom will be falsely reassured.	Maximal NPV (100%)
Clinical Utility	Risks and benefits resulting from test use.	Rates of acceptability, complications and side effects	A highly invasive test is less acceptable to patients and may lead to complications.	Safe, minimally invasive, sensitive and specific, acceptable, minimal side effects
Cost Effectiveness	Direct monetary costs and indirect costs associated with the disease, tests and a misdiagnosis of the disease	Cost Effectiveness Ratio CER: Cost of intervention Effect of intervention	An expensive test is unlikely to be affordable by patients or health service providers including the NHS	Cheap/cost effective

TP, True Positives; TN, True Negatives; FP, False Positives; FN, False Negatives.