Table 2 Trial outcomes—primary, secondary and process indicators.

From: Lactation-focused audio relaxation versus standard care for mothers of very preterm infants (the EXPRESS randomised clinical trial)

 

Study recording (n = 68)

Control (n = 64)

Unadjusted effect estimate (95% CI)

Adjusteda effect estimate (95% CI)

p-value

Primary outcome: 24-h expressed milk weightb (grams)

 Mean (SD)

596.7 (433.6)

467.7 (350.2)

MD 129.1 (−20.8 to 278.9)

MD 73.9 (−61.7 to 209.5)

0.28

 Median [IQR]

521.4 [254.6 to 902.7]

397.8 [176.6 to 719.2]

   

 Min to max

(2 to 1926)

(7 to 1274)

   

 Missing

16

8

   

Secondary outcomes

Expressing ≥750 g milk in 24 hb, n (%)

18 (35)

12 (21)

RR 1.62 (0.86 to 3.02)

RR 1.43 (0.77 to 2.66)

0.26

 Missing

16

8

   

Rate of milk expressed day 21 (g/min), median [IQR]

3.7 [2.4 to 6.2]

3.7 [1.8 to 6.2]

Med Diff 0.0 (−1.7 to 1.7)

Med Diff 0.5 (−1.4 to 2.4)

0.59

 Min to max

(0 to 13)

(0 to 16)

   

 Missing

25

21

   

STAIc score day 21, mean (SD)

48.3 (15.8)

47.3 (15.9)

MD 1.1 (−5.8 to 7.9)

MD −1.9 (−8.2 to 4.3)

0.54

 Min to max

(20 to 80)

(20 to 73)

   

 Score >40, n (%)

25 (58)

23 (56)

   

 Missing

25

23

   

PCL-5d score day 21, median [IQR]

16.5 [9.5 to 24.5]

18 [9 to 32.5]

Med Diff −2.0 (−11.7 to 7.7)

Med Diff −1.4 (−11.8 to 9.1)

0.80

 Min to max

(0 to 61)

(0 to 66)

   

 Score >33, n (%)

6 (14)

10 (23)

   

 Missing

24

20

   

Exclusive breastmilke 36 weeks’ PMA, n (%)

37 (64)

37 (67)

RR 0.95 (0.72 to 1.24)

RR 0.96 (0.74 to 1.24)

0.75

 Missing

10

9

   

Exclusive breastmilke 4 months’ corrected age, n (%)

4 (15)

4 (13)

RR 1.07 (0.29 to 3.89)

RR 1.10 (0.30 to 4.01)

0.89

 Not eligible for assessmentf

25

22

   

 Missing

16

12

   

Any breastmilkg 36 weeks’ PMA, n (%)

51 (88)

47 (85)

RR 1.03 (0.89 to 1.19)

RR 1.03 (0.90 to 1.19)

0.67

 Missing

10

9

   

Process indicators (Day 21):

     

Time spent in skin-to-skin contact (hours), mean (SD)

2.2 (1.9)

2.0 (1.8)

Med Diff 0.0 (−1.2 to 1.2)

Med Diff 0.0 (−0.9 to 0.9)

1.00

 Median [IQR]

2 [0.8 to 3]

2 [1 to 3]

   

 Min to max

(0 to 8)

(0 to 9)

   

 Missing

24

23

   

Expressing episodes in 24 hh, mean (SD)

5.6 (2.4)

5.9 (1.8)

MD −0.3 (−1.2 to 0.6)

MD −0.3 (−1.1 to 0.6)

0.53

 Median [IQR]

6 [5 to 7]

6 [5 to 7]

   

 Min to max

(0 to 11)

(1 to 8)

   

 No longer lactating

3 (6.7)

0 (0.0)

   

 Solely breastfeeding

0 (0.0)

0 (0.0)

   

 Missing

20

21

   

Time spent expressing (hours), mean (SD)

151.5 (90.9)

159.3 (84.9)

   

 Median [IQR]

151.5 [105 to 200]

150 [110 to 195]

Med Diff 3.0 (−36.2 to 42.2)

Med Diff −2.3 (−40.4 to 35.8)

0.90

 Min to max

(0 to 500)

(10 to 480)

   

 Missing

20

21

   

Perception of low milk supply, n (%)

9 (21)

17 (39)

   

 Missing

26

20

   

Direct breastfeedsi, mean (SD)

0.1 (0.4)

0.0 (0.2)

   

 Median [IQR]

0 [0 to 0]

0 [0 to 0]

   

 Min to max

(0 to 2)

(0 to 1)

   

 Missing

40

41

   
  1. Missing observations are excluded from percentage denominators.
  2. PMA postmenstrual age, CI confidence interval, SD standard deviation, IQR interquartile range, RR relative risk, MD mean difference, Med Diff median difference.
  3. aAdjusted for recruiting hospital, gestational age, multiple births and, as noted below for certain outcomes, measurement day and baseline STAI score.
  4. bHighest of any/all submitted logs on days 4, 14 or 21. Adjusted for gestational age at birth, recruitment centre, multiple birth and measurement day.
  5. cSix item Spielberger State-Trait Anxiety Index (STAI), transformed to an equivalent score to 20 item STAI. Score range is 20 to 80, higher score indicates more anxiety. Adjusted for gestational age at birth, recruitment centre, multiple births and baseline STAI.
  6. dPost-traumatic Stress Scale for DSM-5. Score range is 0 to 80, higher score indicates more post-traumatic stress.
  7. eExclusive breastmilk is defined as no infant formula used in the last 24 h. If two babies, then no infant formula in the last 24 h for either baby. Outcome at 4 months’ corrected was not adjusted for multiple births or centre due to collinearity.
  8. fThese participants were recruited in the latter part of the study, which concluded at 36 weeks’ PMA.
  9. gAny breastmilk is defined as any use of breastmilk in the last 24 h, either direct breastfeeding or as expressed milk. If two babies, then any breastmilk for either baby.
  10. hAn expressing episode is defined as where two breasts are expressed simultaneously or where two breasts are expressed sequentially, with the start time of the second breast expression within 10 min of the end time of the first breast expression or where one breast is expressed alone.
  11. iA direct breastfeed is defined as an episode at the breast where the mother felt the baby was sucking and swallowing some milk. If the baby is offered both breasts in a single episode, this is one breastfeed. If the baby stops sucking or swallowing for 30 min or more, then any further feeding is a new breastfeed. If two babies, then the sum of all episodes with both babies.
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