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Table 3 Cox ‘proportional hazards’ regression model to compare 90-day mortality between the 7 approach subgroups

From: The effect of surgical approach in total hip replacement on outcomes: an analysis of 723,904 elective operations from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

Approach

Minimally invasive procedure used

Number for analysis

(i) Unadjusted model (n = 723,747; 2673 deaths) hazard rate ratio [95%CI]

(ii) With covariate adjustment for sex, age, ASA and year of primary, stratified by ‘risk group’ (n = 723,747; 2673 deaths) hazard rate ratio [95%CI]

(iii) With covariate adjustment for sex, age, ASA, year of primary and fixation, stratified by ‘risk group’ (n = 723,747; 2673 deaths) hazard rate ratio [95%CI]

Posterior

No

394,655

1 [referent]

1 [referent]

1 [referent]

Posterior

Yes

22,655

0.80 [0.62–1.04] P = 0.101

0.88 [0.68–1.14] P = 0.344

0.90 [0.69–1.17] P = 0.447

Lat/Ant-Lat/Hard

No

260,353

1.38 [1.27–1.49] P < 0.001

1.14 [1.05–1.24] P = 0.002

1.14 [1.05–1.23] P = 0.002

Lat/Ant-Lat/Hard

Yes

9099

1.21 [0.87–1.69] P = 0.252

1.02 [0.73–1.43] P = 0.896

1.03 [0.74–1.44] P = 0.847

Ant/Other

No

26,578

1.03 [0.83–1.28] P = 0.793

0.96 [0.77–1.19] P = 0.703

0.96 [0.77–1.19] P = 0.715

Ant/Other

Yes

3829

0.80 [0.43–1.50] P = 0.493

0.88 [0.47–1.65] P = 0.697

0.91 [0.49–1.71] P = 0.780

Trans-trochanteric

No

6578

1.49 [1.05–2.11] P = 0.026

1.19 [0.83–1.69] P = 0.342

1.16 [0.81–1.65] P = 0.412

Additional pairwise comparisons:

Lat/Ant-Lat/Hard

No vs. Yes

 

P = 0.452

P = 0.517

P = 0.573

Ant/Other

No vs. Yes

 

P = 0.460

P = 0.807

P = 0.884

Approach

Minimally invasive procedure used

(iv) With covariate adjustment for sex, age, ASA, year of primary, fixation, mechanical and chemical thromboprophylaxis and anaesthetic group, stratified by ‘risk group’ (n = 713,994 with complete information; 2621 deaths) hazard rate ratio [95%CI]

(v) With covariate adjustment for sex, age, ASA, year of primary, fixation, mechanical and chemical thromboprophylaxis, anaesthetic group and quintile of area deprivation, stratified by ‘risk group’ (n = 572,719 with complete information; 2192 deaths) hazard rate ratio [95%CI]

(vi) With covariate adjustment for sex, age, ASA, year of primary, fixation, mechanical and chemical thromboprophylaxis, anaesthetic group, quintile of area deprivation and BMI subgroup, stratified by ‘risk group’ (n = 359,883 with complete information; 1148 deaths) hazard rate ratio [95%CI]

Posterior

No

1 [referent]

1 [referent]

1 [referent]

Posterior

Yes

0.91 [0.70–1.18] P = 0.475

0.93 [0.68–1.27] P = 0.644

0.87 [0.57–1.34] P = 0.525

Lat/Ant-Lat/Hard

No

1.16 [1.06–1.26] P = 0.001

1.11 [1.01–1.21] P = 0.027

1.15 [1.01–1.30] P = 0.029

Lat/Ant-Lat/Hard

Yes

0.91 [0.63–1.31] P = 0.605

0.87 [0.58–1.31] P = 0.512

0.80 [0.41–1.55] P = 0.507

Ant/Other

No

0.96 [0.78–1.20] P = 0.732

0.94 [0.75–1.19] P = 0.620

0.89 [0.63–1.26] P = 0.509

Ant/Other

Yes

0.92 [0.49–1.71] P = 0.787

1.23 [0.61–2.47] P = 0.563

1.01 [0.32–3.15] P = 0.986

Trans-trochanteric

No

1.16 [0.81–1.67] P = 0.409

1.12 [0.75–1.68] P = 0.571

1.12 [0.52–2.41] P = 0.771

Additional pairwise comparisons:

Lat/Ant-Lat/Hard

No vs Yes

P = 0.195

P = 0.250

P = 0.283

Ant/Other

No vs Yes

P = 0.885

P = 0.447

P = 0.833

  1. Lat/Ant-Lat/Hard lateral/anterolateral/Hardinge, Ant/Other anterior/other, ASA American Society of Anesthesiologists Physical Status, BMI body mass index, CI confidence interval