Incidence of symptomatic venous thromboembolism in 2372 knee and hip replacement patients after discharge: data from a thromboprophylaxis registry in Montreal, Canada

Figures & data

Figure 1 Flow diagram of the registry.

Notes: ^aEnoxaparin dose during hospitalization: 30 mg BID. ^bOther therapies prescribed at discharge included warfarin, rivaroxaban, or apixaban. cDabigatran dose, options after discharge: 220, 150 mg DIE. dEnoxaparin dose, options after discharge: 30 mg BID, 40 mg DIE. ePatients were either contacted by phone or seen at the outpatient orthopedic clinic.
Abbreviations: BID, twice daily; DIE, once daily.

Table 1 Patient characteristics specific to the joint replaced

Characteristics	Total (N=2372)	TKA (n=1396)	THA (n=976)
Age (years), mean (±SD)	65.9 (10.4)	66.5 (9.7)	65.2 (11.3)*
Female, n (%)	1431 (60.3)	877 (62.8)	554 (56.8)*
Unilateral, n (%)	2123 (89.5)	1188 (85.1)	935 (95.8)
Bilateral, n (%)	249 (10.5)	208 (14.9)	41 (4.2)*
Enoxaparin dosagea			614
30 mg BID	723 (49.3)	416 (48.7)	307 (50.0)
40 mg DIE	651 (44.3)	374 (43.8)	277 (45.1)
Dabigatran dosageb
220 mg DIE	751 (83.1)	447 (82.5)	304 (84.0)
150 mg DIE	107 (11.8)	63 (11.6)	44 (12.1)
Other dosage/missing data	140 (5.9)	96 (6.9)	44 (4.5)
Patients with PO transfusion(s), n (%)	140 (5.9)	95 (6.8)	45 (4.6)*
Infectionsc, n (%)	26 (1.1)	20 (1.4)	6 (0.6)

Notes:

a Denominator is 1468 for the total cohort, 854 for TKA, and 614 for THA.

b Denominator is 904 for the total cohort, 542 for TKA, and 362 for THA.

c Deep infections that required debridement and washout.

* p-value <0.05 using Pearson’s chi-squared test or Fisher’s exact test, except for age (independent samples Students t-test).

Abbreviations: BID, twice daily; DIE, once daily; PO, postoperative; THA, total hip arthroplasty; TKA, total knee arthroplasty.

Table 2 Patient characteristics according to thromboprophylaxis after discharge

Characteristics	Dabigatran (n=904)	Enoxaparin (n=1468)	p-valuea
Age (years), mean (±SD)	64.1 (10.6)	67.1 (10.1)	<0.001
Female, n (%)	534 (59.1)	897 (61.1)	0.326
Joint replaced, n (%)
Knee	542 (60.0)	854 (58.2)	0.392
Hip	362 (40.0)	614 (41.8)
Treatment length (days), n (%)
<14	6 (0.7)	9 (0.6)	0.237
14	109 (12.1)	156 (10.6)
15–34	10 (1.1)	18 (1.2)
35	736 (81.4)	1218 (83.0)
>35	16 (1.8)	12 (0.8)
Missing data	27 (3.0)	55 (3.7)
DVT history, n (%)b	53 (5.9)	95 (6.5)	0.552
PE history, n (%)	4 (0.4)	13 (0.9)	0.214
Patients with PO transfusion(s), n (%)	62 (6.9)	78 (5.3)	0.121
Infections,c n (%)	16 (1.8)	10 (0.7)	0.013

Notes:

a Pearson’s chi-squared test or Fisher’s exact test, except for age (independent samples Student’s t-test).

b Ten patients with history of both DVT and PE.

c Deep infections that required debridement and washout.

Abbreviations: DVT, deep vein thrombosis; PE, pulmonary embolism; PO, postoperative.

Table 3 Thromboprophylaxis efficacy and safety outcomes for patients prescribed dabigatran or enoxaparin after joint replacement and discharge

Outcomes	Total, n(%) (N=2372)	Dabigatran, n(%) (n=904)	Enoxaparin, n(%) (n=1468)	Absolute risk differencea (per 100 patients, 95% confidence intervals)	p-valueb
Efficacy outcomes
After discharge
Total symptomatic VTE	16 (0.7)	7 (0.8)	9 (0.6)	−0.16 (−0.87; 0.54)	0.641
Proximal DVT	13 (0.6)	6 (0.7)	7 (0.5)	−0.19 (−0.83; 0.45)	0.559
Distal DVT	3 (0.1)	1 (0.1)	2 (0.1)	*	0.672
Symptomatic PE	7 (0.3)	3 (0.3)	4 (0.3)	*	0.543
Safety outcomes
After discharge
Major bleeding events	6 (0.3)	5 (0.6)	1 (0.1)	−0.50 (−0.94; −0.07)	0.033**
Minor bleeding events	688 (30.3)	288 (33.1)	400 (28.5)	−4.57 (−8.46; −0.69)	0.021**
Hematomas	521 (22.9)	217 (24.9)	304 (21.7)	−3.26 (−6.81; 0.30)	0.072
Wound bleeding/discharge	118 (5.2)	53 (6.1)	65 (4.6)	−1.46 (−3.33; 0.42)	0.129
Nose bleeding	69 (3.0)	23 (2.6)	46 (3.3)	0.64 (−0.81; 2.09)	0.389
Hematuria or blood in stool	62 (2.7)	36 (4.1)	26 (1.9)	−2.28 (−3.66; −0.90)	0.001**

Notes: Denominators are the numbers at the last follow-up (12 months): 870 for dabigatran and 1402 for enoxaparin.

a Difference in VTE risk for patients prescribed dabigatran compared to patients prescribed enoxaparin after total joint replacement. A negative value means an increased risk for patients prescribed dabigatran compared to patients prescribed enoxaparin.

b Pearson’s chi-squared test or Fisher’s exact test.

* Numbers too small to obtain significant results.

** Statistically significant with p-value of <0.05.

Abbreviations: DVT, deep vein thrombosis; PE, pulmonary embolism; VTE, venous thromboembolic event.

Table 4 Thromboprophylaxis efficacy and safety outcomes after joint replacement and discharge between knee and hip replacements

Outcomes	Total, n (%) N=2372	TKA, n (%) N=1396	THA, n (%) N=976	Absolute risk differencea (per 100 patients, 95% CI)	p-valueb
Efficacy outcomes
After discharge
Total symptomatic VTE	16 (0.7)	9 (0.7)	7 (0.7)	0.06 (−0.65; 0.77)	0.832
Proximal DVT	13 (0.6)	7 (0.5)	6 (0.6)	0.10 (−0.53; 0.74)	0.745
Distal DVT	3 (0.1)	2 (0.1)	1 (0.1)	*	1.000
Symptomatic PE	7 (0.3)	3 (0.2)	4 (0.4)	*	0.460
Safety outcomes
After discharge
Major bleeding events	6 (0.3)	3 (0.2)	3 (0.3)	0.09 (−0.34; 0.52)	0.699
Minor bleeding events	688 (30.3)	437 (33.0)	251 (26.5)	−6.53 (−10.36; −2.70)	0.001**
Hematomas	521 (22.9)	323 (24.4)	198 (20.9)	−3.51 (−7.01; 0.00)	0.050
Wound bleeding/discharge	118 (5.2)	89 (6.7)	29 (3.1)	−3.66 (−5.51; −1.81)	<0.001**
Nose bleeding	69 (3.0)	43 (3.2)	26 (2.7)	−0.50 (−1.94; 0.93)	0.489
Hematuria or blood in stool	62 (2.7)	35 (2.6)	27 (2.7)	0.20 (−1.15; 1.56)	0.768

Notes: Denominators are the numbers at the last follow-up (12 months): 1324 for TKA and 948 for THA.

a Difference in VTE risk for patients with TKA compared to patients with THA. A negative value means an increased risk for TKA patients compared to THA patients.

b Pearson’s Chi-squared test or Fischer’s exact test.

* Numbers too small to obtain significant results.

** Statistically significant with p-value of <0.05.

Abbreviations: CI, confidence interval; DVT, deep vein thrombosis; PE, pulmonary embolism; THA, total hip arthroplasty; TKA, total knee arthroplasty; VTE, venous thromboembolic event.