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Table 2 Regression models to compare approach groups for revision risk (n = 723,747 with complete information)

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

(i) Stratified Cox proportional hazards regression models, with stratification by age/sex/risk groups

Approach

Minimally invasive procedure used

Unadjusted Hazard rate ratio (95%CI)

With adjustment for fixation and ASA hazard rate ratio (95%CI)

With adjustment for fixation, ASA and BMI subgroup (n = 443,657) hazard rate ratio (95%CI)

Posterior

No

1 [referent]

1 [referent]

1 [referent]

Posterior

Yes

0.99 [0.89–1.10] P = 0.864

0.92 [0.83–1.02] P = 0.110

0.89 [0.77–1.02] P = 0.097

Lat/Ant-Lat/Hard

No

1.05 [1.01–1.09] P = 0.009

1.07 [1.03–1.11] P = 0.001

1.12 [1.06–1.17] P < 0.001

Lat/Ant-Lat/Hard

Yes

1.31 [1.16–1.50] P < 0.001

1.28 [1.13–1.46] P < 0.001

1.02 [0.80–1.30] P = 0.861

Ant/Other

No

1.04 [0.95–1.14] P = 0.431

1.03 [0.94–1.13] P = 0.561

1.01 [0.88–1.15] P = 0.921

Ant/Other

Yes

1.67 [1.36–2.05] P < 0.001

1.48 [1.21–1.82] P < 0.001

1.03 [0.71–1.51] P = 0.870

Trans-trochanteric

No

1.22 [1.07–1.40] P = 0.004

1.40 [1.22–1.60] P < 0.001

1.48 [1.14–1.91] P = 0.003

Additional pairwise comparisons:

Lat/Ant-Lat/Hard

No vs. Yes

P = 0.001

P = 0.005

P = 0.475

Ant/Other

No vs. Yes

P < 0.001

P = 0.001

P = 0.902

(ii) FPM models, with adjustment for time-varying effects of age, sex, risk group

Approach

Minimally invasive procedure used

Unadjusted Coefficient (95%CI)

With adjustment for fixation and ASA, as time-varying effects Coefficient (95%CI)

Posterior

No

0 [Referent]

0 [Referent]

Posterior

Yes

−0.006 [−0.109–0.096] P = 0.903

−0.081 [−0.183–0.022] P = 0.125

Lat/Ant-Lat/Hard

No

0.056 [0.019–0.093] P = 0.003

0.069 [0.031–0.106] P < 0.001

Lat/Ant-Lat/Hard

Yes

0.282 [0.154–0.411] P < 0.001

0.264 [0.135–0.392] P < 0.001

Ant/Other

No

0.031 [−0.063–0.126] P = 0.516

0.019 [−0.075–0.114] P = 0.688

Ant/Other

Yes

0.516 [0.311–0.721] P < 0.001

0.380 [0.174–0.585] P < 0.001

Trans-trochanteric

No

0.213 [0.075–0.350] P = 0.002

0.309 [0.170–0.448] P < 0.001

Additional pairwise comparisons:

Lat/Ant-Lat/Hard

No vs. Yes

P = 0.001

P = 0.003

Ant/Other

No vs. Yes

P < 0.001

P = 0.002

  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
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BMC Medicine

ISSN: 1741-7015

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