Table 2.

 Diagnostic information for the biochemical diagnosis of CHF

Analyte	Cut off concentration (ng/l)	Sensitivity (95% CI)	Specificity (95% CI)	PPV	NPV	Diagnostic accuracy
BNP	100*	96% (92 to 99)	61% (52 to 70)	0.75	0.93	80%
	118	95% (90 to 98)	64% (55 to 73)	0.76	0.91	81%
	160	90% (84 to 95)	73% (64 to 81)	0.80	0.87	83%
	295†	80% (73 to 87)	86% (78 to 92)	0.87	0.78	83%
NT-proBNP	292	95% (90 to 98)	53% (43 to 62)	0.71	0.90	76%
	125/450*	94% (89 to 97)	46% (37 to 56)	0.68	0.87	73%
	476	90% (84 to 95)	65% (55 to 74)	0.76	0.85	79%
	825†	87% (80 to 92)	81% (72 to 88)	0.84	0.84	84%

*Approved cut off concentrations for the AxSYM BNP assay (100 ng/l) and Elecsys NT-proBNP assay (dual cut off 125 ng/l for patients <75 years of age and 450 ng/l for those ⩾75 years of age); †criterion concentrations corresponding to the highest diagnostic accuracy (that is, optimal cut off concentrations with minimum false negative and false positive results).

CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value.