SIMPREDICT

Simpredict Tasks

Task 203: Minimal C-statistic required
Input the disease incidence and the test-positive threshold (based on PPV and SR) to obtain the minimal C-statistic required to identify such a group.

Disease Incidence	25 50 75 100 125 150 175 200

Minimal PPV	1 % 2 % 5 % 10 % over 10 years
Minimal SR	5 % 10 % 20 %

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At an incidence of 50 / 100,000 person-years, a meaningful subgroup (PPV > 5%; SR > 10%) can be identified when the model achieves a C-statistic of at least 0.81.

Search Detail SR: sensitivity rate; PPV: positive predictive value; TP: test positive rate

Risk threshold	Minimal
(over 10 years)	C-statistic	SR	PPV	TP
1%	0.84	0.564	0.024	0.116	Best suboptimal match
2%	0.84	0.370	0.040	0.045	Best suboptimal match
3%	0.81	0.202	0.052	0.019	Good
4%	0.81	0.143	0.067	0.011	Good
5%	0.81	0.104	0.081	0.006	Good
6%	0.84	0.126	0.101	0.006	Good
7%	0.84	0.105	0.116	0.004	Good
8%	0.84	0.087	0.130	0.003	Best suboptimal match
9%	0.84	0.074	0.145	0.003	Best suboptimal match
10%	0.84	0.063	0.157	0.002	Best suboptimal match