Table 6.

Fivefold cross-validation results.

Fold	No. Obs	Population prevalence parameters	% Sensitivity	% Specificity	ROC area	Odds ratio	% PPV*	% NPV*
1	28	0.35	78.6	92.9	0.857	47.7	3.7	99.9
		30	78.6	92.9	0.857	47.7	82.5	91.0
2	26	0.35	84.6	92.3	0.855	66	3.7	99.9
		30	84.6	92.3	0.885	66	82.5	93.3
3	28	0.35	85.7	64.3	0.750	10.8	0.8	99.9
		30	85.7	64.3	0.750	10.8	50.7	91.3
4	26	0.35	92.3	92.3	0.923	144	4.0	100.0
		30	92.3	92.3	0.923	144	83.7	96.6
5	26	0.35	84.6	92.3	0.885	66	3.7	99.9
		30	84.6	92.3	0.885	66	82.5	93.3
Scored 15 biomarker set	134	0.35	85.1	86.6	0.858	36.7	2.2	99.9
		30	85.1	86.6	0.858	36.7	73.1	93.1

Results are reported across prevalence values that may be clinically encountered, 0.35% prevalence = mean prevalence for schizophrenia (applicable to screening) within the Australian population, where 12 monthly MEAN schizophrenia prevalence is estimated as equivalent to 0.35/100 (0.35%), 30% prevalence = estimated prevalence rate among a clinical population (where expected conversion rate to schizophrenia is 30–35% at 1-year follow-up) (89).

*Percent positive predictive value and negative predictive value.