Table 2. Outcome by treatment group stratified into quartiles for TA NO-metabolite (NO_x) levels at study entry.

Survival without BPD, N/total (%)
NO metabolite	iNO (n=34)	Control (n=36)
Lowest quartile	7/8 (87.5%)*	3/9 (33.3%)
Second quartile	3/11 (27.3%)	2/7 (28.6%)
Third quartile	3/7 (42.9%)	2/10 (20%)
Highest quartile	3/8 (37.5%)	3/10 (30%)

Abbreviations: BPD, bronchopulmonary dysplasia; iNO, inhaled nitric oxide; TA, tracheal aspirate.

^*P=0.027 vs all other treated infants; P=0.07 vs control infants in lowest quartile.

Quartiles are related to the median value (27.1 nmoles mg^–1 protein): lowest<15.7; second 15.7–27.1; third 27.2–54.6; highest >54.6.