Table 3.

—Value of Feno in Predicting the Need for Acute Medical Attention for Asthma Over 3 Mo (One Visit)

	Hospitalization		ED Visit		Unscheduled Doctor Visit		Any Acute Visit
Feno, ppb	PPV, %	NPV, %	PPV, %	NPV, %	PPV, %	NPV, %	PPV, %	NPV, %
< 20	0.6	98.4	15.7	81.3	20.5	87.0	29.5	71.4
> 35	2.3	99.6	18.5	83.0	14.8	83.8	30.6	72.5
> 50	3.2	99.7	18.5	82.7	14.6	84.0	31.2	72.2
Lowa	0.5	98.3	16.0	81.3	19.8	87.1	29.4	71.4
Highb	2.7	99.7	19.4	83.4	16.1	84.7	32.8	73.6

NPV = negative predictive value; PPV = positive predictive value. See Table 1 legend for expansion of other abbreviations.

^aFeno < 20 ppb for those aged < 12 y and < 25 ppb for those ≥ 12 y.

^bFeno > 35 ppb for those aged < 12 y and > 50 ppb for those ≥ 12 y.