Table 1.

Demographics of the infants who underwent pulmonary function testing (development cohort) and of infants whose parents completed the four week diary card (validation cohort)

The data are presented as median (range) or n (%)
	Development cohort	Validation cohort
N	76	227
Male	42 (55%)	113 (50%)
Gestational age (week)	26 [23 to 28]	27 [23 to 28]
Birth weight (g)	870 [458 to 1335]	890 [500 to 1459]
Birth weight z-score	−0.47 [−3.45 to 1.73]	−0.46 [−3.30 to 2.41]
Small for gestational age (birth weight z-score <−1.28)	13 (17%)	53 (23%)
Multiple birth	16 (21%)	59 (26%)
Race
White	56 (74%)	208 (92%)
black	13 (17%)	8 (4%)
Other	7 (9%)	11 (5%)
Maternal smoking in pregnancy	13 (20%)	46 (20%)
Oxygen dependent at 28 days	64 (84%)	190 (84%)
Oxygen dependent at 36 wk PMA	45 (59%)	142 (63%)
Oxygen dependent at discharge	14 (18%)	50 (22%)
Days on ventilator support	14 [0 to 112]	8 [0 to 62]
Air leak	11 (14%)	28 (12%)