Table 2 Univariate analysis for variable selection (p < 0.20) and multivariable Cox regression analysis for risk factors.

From: Axial impairment and falls in Parkinson’s disease: 15 years of subthalamic deep brain stimulation

 

Univariate analysis

Multivariable Cox regression

 

HR

95% CI (lower–upper)

p value

HR

95% CI (lower–upper)

p value

Axial impairment

Age at disease onset

1.058

1.025–1.093

<0.001

1.095

1.044–1.148

<0.001

Disease duration at surgery

1.090

1.035–1.148

0.001

0.978

0.889–1.076

0.649

Clinical phenotype (AR vs. tremorigen and mixed)

0.521

0.325–0.834

0.007

0.716

0.358–1.434

0.346

WMH on brain MRI

2.595

1.340–5.024

0.005

1.715

0.820–3.585

0.152

Baseline UPDRS part III OFF medication

1.017

1.002–1.032

0.030

0.992

0.959–1.026

0.638

Baseline UPDRS part III ON medication

1.053

1.028–1.078

<0.001

1.002

0.949–1.059

0.931

Baseline H&Y OFF medication

1.587

1.223–2.061

0.001

1.127

0.626–2.030

0.690

Baseline H&Y ON medication

1.393

1.007–1.926

0.045

0.660

0.395–1.103

0.113

Baseline axial score OFF medication

1.179

1.104–1.258

<0.001

1.104

0.980–1.243

0.103

Baseline axial score ON medication

1.544

1.373–1.736

<0.001

1.468

1.217–1.770

<0.001

Baseline MDRS

0.955

0.912–0.999

0.045

1.064

0.985–1.150

0.114

Baseline frontal score

0.935

0.901–0.969

<0.001

0.952

0.909–0.998

0.042

Baseline L-Dopa responsiveness of axial signs

0.987

0.979–0.996

0.005

1.007

0.982–1.033

0.582

Falls

Age at disease onset

1.037

1.008–1.067

0.013

1.051

1.011–1.092

0.011

Disease duration at surgery

1.097

1.046–1.152

<0.001

1.117

1.117–1.045

0.001

Clinical phenotype (AR vs. tremorigen and mixed)

1.839

1.184–2.856

0.007

1.869

1.114–3.135

0.018

Baseline UPDRS part III ON medication

1.026

1.000–1.052

0.047

0.986

0.949–1.025

0.489

Baseline H&Y OFF medication

1.368

1.085–1.725

0.008

0.932

0.581–1.494

0.769

Baseline H&Y ON medication

1.497

1.086–2.063

0.014

1.085

0.710–1.659

0.706

Baseline axial score OFF medication

1.126

1.062–1.194

<0.001

1.045

0.956–1.142

0.336

Baseline axial score ON medication

1.382

1.242–1.537

<0.001

1.291

1.133–1.471

<0.001

Baseline L-Dopa responsiveness of axial signs

0.989

0.980–0.997

0.009

0.996

0.975–1.018

0.733

Baseline frontal score

0.974

0.943–1.007

0.117

1.022

0.985–1.060

0.243

  1. Bold font indicates statistical significance of the variable at the Cox regression analysis.
  2. AR akinetic/rigid, CI confidence interval, H&Y Hoehn and Yahr scale, HR hazard ratio, MDRS Mattis dementia rating scale, UPDRS unified Parkinson’s disease rating scale, WMH white matter hyperintensities.
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