Table 2. Difference between the two groups based on categorical variables.

ciNPT: closed incision negative pressure therapy, df: degrees of freedom, BL: bilateral, CL: contralateral, UL: unilateral

		Group A (conventional dressing)	Group B (ciNPT)	Chi-square	df	p-value
Incision type	Transverse	17	22	1.34	1	0.24
	Wise pattern	45	37
Surgical procedure	Mastectomy and implant insertion	37	37	0.80	2	0.66
	Oncoplastic reduction	18	13
	Change of implant	8	9
Smoker	Yes	7	4	4.25	2	0.11
	No	34	43
	Ex-smoker	21	12
Laterality	BL	20	20	0.68	2	0.79
	CL	20	20
	UL	22	19
Radiotherapy	Yes	5	8	0.95	1	0.32
	No	57	51
Neoadjuvant chemotherapy	Yes	10	12	0.36	1	0.54
	No	52	47