Table 3.

The sensitivity, specificity, PPV, NPV, LR & post-test odds with 95% confidence intervals of HARK at different cut off scores

Hark cut off scores	% of study sample	Sensitivity with 95% C.I.	Specificity with 95% C.I.	Positive predictive value with 95% C.I.	Negative predictive value with 95% C.I.	Likelihood ratio with 95% C.I.	Post-test odds
= 4	1%	4% (3% to 13%)	100% (98% to 100%)	100% (22 to 100%)	78% (72% to 83%)	Undefined	Undefined
≥3	6%	26% (15% to 40%)	100% (98% to 100%)	100% (81% to 100%)	82% (76% to 87%)	Undefined	Undefined
≥2	13%	51% (37% to 65%)	98% (95% to 100%)	90% (73% to 98%)	87% (82% to 91%)	30 (10 to 96)	9
≥1	22%	81% (69% to 90%)	95% (91% to 98%)	83% (70% to 91%)	94% (90% to 97%)	16 (8 to 31)	5
≥0	100%	100% (93% to 100%)	0% (0% to 2%)	23% (18% to 29%)	error	1	0.3

When the specificity is 100%, the likelihood ratio and post test odds are undefined.

Confidence intervals for likelihood ratios are approximate since they were calculated by the delta method which is less reliable when some cell sizes are small (Armitage P, Matthews JNS, Berry G. Statistical methods in medical research. Oxford; Blackwell, 1994).