Table 4.

Exploratory subgroup analysis: adjusted primary and secondary outcomes according to administration of tranexamic acid versus placebo in patients who had simple mastectomy/sentinel node biopsy at centre A

	TXA (n = 52) versus placebo (n = 56)	P
Primary outcome
Drain production in first 24 h*, †	−39 (−69, −14)	0·001
Secondary outcomes ‡
Early haematoma	TXA 0 versus placebo 3#	0·244
Total drain production*, †	−46 (−81, −18)	0·001
Days with drain*	−23 (−83, −10)	0·001
Drain removed at 24 h§	6·60 (2·07, 21·22)	0·001
Drain volume in 24 h before removal*	−9 (−30, 9)	0·309
Late haematoma, postoperative infection or wound rupture	TXA 5 versus placebo 6#	1·000
Seroma ¶
Aspiration required§	1·11 (0·44, 2·79)	0·821
≥ 5 aspirations§	0·47 (0·15, 1·50)	0·203
Cumulative seroma ≥ 500 ml§	1·05 (0·38, 2·90)	0·930
Chronic seroma§	0·18 (0·04, 0·89)	0·035

Values in parentheses are 95 per cent confidence intervals.

^*Ratio between logarithmic mean as percentage difference; univariable general linear model adjusted for drug and wound surface area;

^†additionally adjusted for surgeon seniority.

^‡Number of patients with early haematoma calculated from all patients; patients with early haematoma excluded from other secondary postoperative outcome registrations.

^§Odds ratio: logistic regression model adjusted for wound surface area.

^¶Patients with early or late haematoma, infection or wound rupture excluded from seroma registrations. TXA, tranexamic acid.

^#Fisher's exact test owing to number of patients being too low for logistic regression analysis.