Table 4.

Derivation and external validation of the prognostic rule for respiratory insufficiency and death

Variable	c-statistic (95% CI)	Sensitivity % (95% CI)	Specificity % (95% CI)	PPV % (95% CI)	NPV % (95% CI)
Respiratory insufficiency
Derivation	0.86 (0.84−0.89)	83 (71−91)	81 (72−89)	77 (65−86)	86 (77−93)
External validation	0.74 (0.72−0.75)	53 (51−55)	82 (81−83)	62 (60−64)	76 (75−77)
Death
Derivation	0.84 (0.80−0.89)	83 (63−95)	81 (73−87)	46 (30−61)	96 (91−99)
External validation	0.72 (0.71−0.74)	47 (44−50)	82 (81−83)	36 (34−38)	88 (87−89)

PPV: positive predictive value; NPV: negative predictive value. Sensitivity, specificity, PPV and NPV were based on the following cut-off points: respiratory insufficiency ≥0.45 and death ≥0.11.