Table 6.

PPVs and NPVs for ERI-2 (score range 0–44) with cut-off values 12, 19, 26 and 33 for different possible prevalences of endometriosis

Possible prevalences (%)	ERI-2≥12		ERI-2≥19		ERI-2≥26		ERI-2≥33
	Sensitivity 78.1% Specificity 79.7%		Sensitivity 45.2% Specificity 92.6%		Sensitivity 24.5% Specificity 98.0%		Sensitivity 10.3% Specificity 100.0%
	PPV (%)	NPV (%)	PPV (%)	NPV (%)	PPV (%)	NPV (%)	PPV (%)	NPV (%)
2.0	7.3	99.4	11.1	98.8	20.0	98.5	29.6*	98.2
1.0	3.7	99.7	5.8	99.4	11.0	99.2	17.2*	99.1
0.5	1.9	99.9	3.0	99.7	5.8	99.6	9.4*	99.5
0.1	0.4	100.0	0.6	99.9	1.2	99.9	2.0*	99.9

Only participants with complete data for the predictors included in ERI-1 and ERI-2 (155 cases and 148 controls) were included in the analyses.

*PPV for ERI-2 cut-off ≥33 was calculated using a specificity of 99.5%, not 100.0%.

ERI-1, Endometriosis Risk Index Variant 1; ERI-2, Endometriosis Risk Index Variant 2; NPV, negative predictive value; PPV, positive predictive value.