Tranexamic acid reduces intraoperative occult blood loss and tourniquet time in obese knee osteoarthritis patients undergoing total knee arthroplasty: a prospective cohort study

Figures & data

Figure 1 Study cohort and design.

Abbreviations: TKA, total knee arthroplasty; PLAGH, Chinese PLA General Hospital.

Table 1 Clinical characteristics of study population

Items	Total, N = 304
Gender
Male	54 (17.8%)
Female	250 (82.2%)
Age (years)	66.06 ± 7.36
Hypertension	173 (56.9%)
Diabetes mellitus	45 (14.8%)
Cardiovascular diseases	46 (15.1%)
Cerebral infarction	25 (8.2%)
Anticoagulation therapy
Rivaroxaban	181 (59.5%)
LMWH	123 (40.5%)

Abbreviation: LMWH, low-molecular-weight heparin.

Table 2 Comparison of clinical baseline characteristics between tranexamic acid group and non-tranexamic acid group

	Tranexamic acid group	Non-tranexamic acid group	Statistics*	P-value
	N = 146 (52.0%)	N = 158 (48.0%)
Gender			0.338	0.561
Male	24 (16.4%)	30 (19.0%)
Female	122 (83.6%)	128 (81.0%)
Age (years)	66.44 ± 6.84	65.70 ± 7.82	0.870	0.385
Hypertension	90 (61.6%)	83 (52.5%)	2.569	0.109
Diabetes mellitus	23 (15.8%)	22 (13.9%)	0.201	0.654
Cardiovascular diseases	17 (11.6%)	29 (18.4%)	2.661	0.103
Cerebral infarction	15 (10.3%)	10 (6.3%)	1.565	0.211
Anticoagulation therapy			0.000	0.986
Rivaroxaban	87 (59.6%)	94 (59.5%)
LMWH	59 (40.4%)	64 (40.5%)

Notes:

* For normally distributed data, differences between groups were compared by Student’s t-test and shown as T-statistics. For categorical data, differences between groups were compared by Pearson’s chi-squared test and shown as χ²-statistics.

Abbreviation: LMWH, low-molecular-weight heparin.

Table 3 Comparison of perioperative parameters between tranexamic acid group and non-tranexamic acid group

	Tranexamic acid group	Non-tranexamic acid group	Statistics*	P-value
	N = 146 (52.0%)	N = 158 (48.0%)
Preoperative 1 d Hb (g/L)	131.96 ± 11.89	131.41 ± 13.20	0.383	0.702
Preoperative 1 d HCT (%)	39.50 ± 3.26	39.36 ± 3.62	0.352	0.725
Postoperative 1 d Hb (g/L)	127.41 ± 13.59	120.73 ± 13.86	4.235	0.000
Postoperative 1 d HCT (%)	37.44 ± 3.68	35.61 ± 3.84	4.235	0.000
Total preoperative blood volume (mL)	3,901.77 (3,667.16, 4,255.21)	3,986.34 (3,614.81, 4,405.84)	−0.398	0.690
Theoretical blood loss volume (mL)	85.53 (−9.62, 156.49)	161.23 (36.06, 243.57)	−4.579	0.000
Intraoperative blood loss volume (mL)	203.63 ± 74.28	210.13 ± 75.87	−0.753	0.452
Intraoperative red cell transfusion volume (mL)	415.58 ± 118.87	403.01 ± 130.17	0.877	0.381
Actual blood loss volume (mL)	494.29 (401.39, 593.98)	553.98 (440.33, 662.33)	−3.292	0.001
Occult blood loss volume (mL)	294.97 ± 151.18	348.39 ± 173.04	−2.856	0.005
Postoperative drainage volume (mL)	54.44 ± 44.03	62.61 ± 59.93	−1.346	0.179
Operation time (min)	110.00 (95.00, 121.00)	111.00 (98.50, 128.00)	−1.212	0.225
Tourniquet time (min)	56.50 (46.00, 63.25)	61.00 (51.25, 71.00)	−3.549	0.000
Postoperative local swelling	7 (4.8%)	9 (5.7%)	0.124	0.725

Notes:

* For normally distributed data, differences between groups were compared by Student’s t-test and shown as T-statistics. For abnormally distributed variables or those with heterogeneity of variance, differences between groups were compared by Mann–Whitney U-test and shown as Z-statistics. For categorical data, differences between groups were compared by Pearson’s chi-squared test and shown as χ²-statistics.

Abbreviations: Hb, hemoglobin; HCT, hematocrit.

Table 4 Subgroup analysis of baseline characteristics between obese and non-obese groups

	Obese group N = 130				Non-obese group N = 174
	Tranexamic acid group N = 60	Non-tranexamic acid group N = 70	Statistics*	P-value	Tranexamic acid group N = 86	Non-tranexamic acid group N = 88	Statistics*	P-value
Gender			1.121	0.290			0.010	0.920
Male	5 (8.3%)	10 (14.3%)			19 (22.1%)	20 (22.7%)
Female	55 (91.7%)	60 (85.7%)			67 (77.9%)	68 (77.3%)
Age (years)	65.82 ± 7.00	64.80 ± 7.80	0.694	0.489	66.87 ± 6.73	66.42 ± 7.81	0.408	0.684
Hypertension	47 (78.3%)	43 (61.4%)	4.334	0.037	43 (50.0%)	40 (45.5%)	0.360	0.548
Diabetes mellitus	13 (21.7%)	9 (12.9%)	1.783	0.182	10 (11.6%)	13 (14.8%)	0.375	0.540
Cardiovascular diseases	4 (6.7%)	11 (15.7%)	2.591	0.107	13 (15.1%)	18 (20.5%)	0.847	0.358
Cerebral infarction	5 (8.3%)	4 (5.7%)	0.058	0.810	10 (11.6%)	6 (6.8%)	1.205	0.272
Anticoagulation therapy			0.028	0.868			0.033	0.857
Rivaroxaban	36 (60.0%)	43 (61.4%)			51 (59.3%)	51 (58.0%)
LMWH	24 (40.0%)	27 (38.6%)			35 (40.7%)	37 (42.0%)

Notes:

* For normally distributed data, differences between groups were compared by Student’s t-test and shown as T-statistics. For categorical data, differences between groups were compared by Pearson’s chi-squared test and shown as χ²-statistics.

Abbreviation: LMWH, low-molecular-weight heparin.

Table 5 Subgroup analysis of perioperative parameters between obese and non-obese groups

	Obese group N = 130				Non-obese group N = 174
	Tranexamic acid group, N = 60	Non-tranexamic acid group, N = 70	Statistics*	P-value	Tranexamic acid group, N = 86	Non-tranexamic acid group, N = 88	Statistics*	P-value
Preoperative 1 d Hb (g/L)	132.52 ± 8.70	133.37 ± 12.46	−0.446	0.656	131.57 ± 13.72	129.84 ± 13.63	0.834	0.406
Preoperative 1 d HCT (%)	39.74 ± 2.35	40.04 ± 3.57	−0.555	0.580	39.33 ± 3.78	38.82 ± 3.58	0.918	0.360
Postoperative 1 d Hb (g/L)	127.72 ± 10.34	123.13 ± 12.46	2.261	0.025	127.20 ± 15.52	118.83 ± 14.67	3.656	0.000
Postoperative 1 d HCT (%)	37.70 ± 2.85	36.41 ± 3.37	2.333	0.021	37.27 ± 4.17	34.99 ± 4.09	3.650	0.000
Total preoperative blood volume (mL)	4,097.95 (3,787.49, 4,311.89)	4,168.11 (4,009.29, 4,565.07)	−1.119	0.263	3,784.57 (3,500.10, 4,147.15)	3,659.57 (3,395.03, 4,202.13)	−0.856	0.392
Theoretical blood loss volume (mL)	75.58 (−17.18, 166.57)	175.06 (30.46, 264.48)	−3.066	0.002	84.49 (−9.79, 174.84)	155.28 (72.84, 244.17)	−3.419	0.001
Intraoperative blood loss volume (mL)	209.17 ± 87.09	212.14 ± 84.03	−0.198	0.843	199.77 ± 64.11	208.52 ± 69.16	−0.886	0.388
Intraoperative red cell transfusion volume (mL)	412.50 ± 126.18	420.00 ± 109.40	−0.363	0.717	417.73 ± 114.20	389.48 ± 143.78	1.433	0.154
Actual blood loss volume (mL)	499.93 ± 148.06	578.07 ± 186.74	−2.612	0.010	497.68 ± 140.15	542.96 ± 157.73	−2.000	0.047
Occult blood loss volume (mL)	290.76 ± 153.37	365.92 ± 117.85	−2.558	0.012	297.91 ± 150.46	334.44 ± 168.84	−1.506	0.134
Postoperative drainage volume (mL)	49.67 ± 40.43	57.14 ± 51.97	−0.904	0.368	57.77 ± 46.32	66.97 ± 65.54	−1.067	0.287
Operation time (min)	114.50 (98.25, 129.25)	115.00 (99.00, 130.00)	−0.949	0.343	105.00 (95.00, 120.00)	110.00 (100.00, 130.00)	−0.658	0.510
Tourniquet time (min)	58.00 (45.00, 66.25)	68.00 (60.00, 76.00)	−3.546	0.000	56.00 (47.00, 62.00)	60.00 (50.00, 66.00)	−1.404	0.160
Postoperative local swelling	2 (3.3%)	7 (10.0%)	1.314	0.252	5 (5.8%)	2 (2.3%)	0.644	0.422

Notes:

* For normally distributed data, differences between groups were compared by Student’s t-test and shown as T-statistics. For abnormally distributed variables or those with heterogeneity of variance, differences between groups were compared by Mann–Whitney U-test and shown as Z-statistics. For categorical data, differences between groups were compared by Pearson’s chi-squared test and shown as χ²-statistics.

Abbreviations: Hb, hemoglobin; HCT, hematocrit.