Table 1.

Patient demographics.

	Group
	Powder Group (n = 42)		Bead Group (n = 53)		Total		p-values
	Mean/Freq	%/SE	Mean/Freq	%/SE	Mean/Freq	%/SE
Age (years)	59.83	2.00	67.89	1.12	64.33	1.15	0.002*
BMI (kg/m2)	28.98	0.95	29.15	0.86	29.07	0.63	0.79
Gender							0.26
Female (n = 62)	30	71.4	32	60.4	62	65.3
Male (n = 33)	12	28.6	21	39.6	33	34.7
Total (n = 95)	42	100.0	53	100.0	95	100.0
ASA Class							0.58
I (n = 1)	1	2.4	0	0.0	1	1.1
II (n = 37)	18	42.9	19	35.8	37	38.9
III (n = 55)	22	52.4	33	62.3	55	57.9
IV (n = 2)	1	2.4	1	1.9	2	2.1
Total (n = 95)	42	100.0	53	100.0	95	100.0
Diabetes							0.28
Non-diabetic (n = 87)	37	88.1	50	94.3	87	91.6
Diabetic (n = 8)	5	11.9	3	5.7	8	8.4
Total (n = 95)	42	100.0	53	100.0	95	100.0
Smoking Status							0.45
Non-smoker (n = 43)	19	46.3	24	45.3	43	45.7
Current Smoker (n = 2)	0	0.0	2	3.8	2	2.1
Former Smoker (n = 49)	22	53.7	27	50.9	49	52.1
Total (n = 94)	41	100.0	53	100.0	94	100.0
Estimated blood loss (cc)	1023.6	144.3	1099.5	140.9	1065.9	100.8	0.86
Length of surgery (minutes)	410.8	21.6	382.9	15.0	395.3	12.7	0.29
Number of levels	9.1	0.6	11.3	0.6	10.3	0.5	0.03*
Revision Status							0.34
Primary (n = 25)	22	30.6	3	13.0	25	26.3
Revision (n = 70)	50	69.4	20	87.0	70	73.7
Total (n = 95)	72	100.0	23	100.0	95	100.0
Osteotomy							0.12
No Osteotomy (n = 56)	49	68.1	7	30.4	56	58.9
Osteotomy (n = 39)	23	31.9	16	69.6	39	41.1
Total (n = 95)	72	100.0	23	100.0	95	100.0
Durotomy							0.69
No durotomy (n = 72)	31	73.8	41	77.4	72	75.8
Durotomy (n = 23)	11	26.2	12	22.6	23	24.2
Total (n = 95)	42	100.0	53	100.0	95	100.0

BMI= body mass index, ASA = American Society of Anaesthesiologists score, Cc = cubic centimeters. P-values rounded to two decimal points unless p < 0.05. Missing values for smoking were n = 1 (1%). No values were missing for age, BMI, gender, ASA class, diabetes, estimated blood loss, length of surgery, revision status, osteotomy, number of levels, or durotomy.

^⁎p -value less than 0.05.