Table 2.

Primary and Secondary Outcomes (Intention-to-Treat Population).

Outcome and Feeding Subgroup	Buprenorphine (N = 33)	Morphine (N = 30)	Difference (95% CI)*	P Value
			days
No. of infants
Bottle-feeding	21	21
Breast-feeding	12	9
Primary outcome
Median duration of treatment (range) — days	15 (3 to 67)	28 (13 to 67)	−13 (−21 to −7)	<0.001†
Bottle-feeding	15 (3 to 67)	28 (13 to 67)	−13 (−23 to −6)
Breast-feeding	20 (3 to 55)	28 (16 to 52)	−8 (−30 to 2)
Secondary outcomes
Median length of hospital stay (range) — days	21 (7 to 71)	33 (18 to 70)	−12 (−22 to −7)	<0.001†
Bottle-feeding	21 (7 to 71)	33 (18 to 70)	−12 (−23 to −7)
Breast-feeding	26 (7 to 58)	32 (20 to 58)	−8 (−29 to 2)
Use of supplemental phenobarbital — no. (%)	5 (15)	7 (23)		0.36‡
Bottle-feeding	2 (6)	4 (13)
Breast-feeding	3 (9)	3 (10)

^*The difference between the buprenorphine group and the morphine group was calculated with the use of the Hodges–Lehmann estimator as the median of all paired differences between observations in the two groups with the corresponding nonparametric 95% confidence interval (CI).

^†This P value was calculated by means of the van Elteren test.

^‡This P value was calculated by means of the Cochran–Mantel–Haenszel test.