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Table 4 Logistic regression analysis of factors associated with having post-operative hyponatraemia following elective primary hip and knee arthroplasty

From: Prevalence, risk factors, and complications associated with hyponatraemia following elective primary hip and knee arthroplasty

 

Unadjusted Odds ratio (95% CI)

p-value

Adjusted Odds ratio (95% CI)*

p-value

Age (years)

1.05 (1.03–1.07)

< 0.001

1.07 (1.02–1.13)

0.007

Height (cm)

0.97 (0.95–0.99)

0.001

0.95 (0.93–1.01)

0.220

Weight (kg)

0.99 (0.98–1.00)

0.019

1.02 (0.99–1.05)

0.151

ASA grade

1 (reference)

1.0 (reference)

-

1.0 (reference)

-

2

2.09 (0.93–4.68)

0.074

0.64 (0.24–1.78)

0.371

3

2.82 (1.20–6.62)

0.017

0.51 (0.13–1.66)

0.245

Peripheral nerve block

1.30 (0.95–1.78)

0.100

1.31 (0.56–3.02)

0.534

Pre-operative Na (mmol/L)

0.72 (0.67–0.77)

< 0.001

0.66 (0.55, 0.78)

< 0.001

Fasting glucose (mmol/L)

1.38 (1.21–1.56)

< 0.001

1.33 (1.08, 1.64)

0.007

Pre-operative haemoglobin (g/L)

0.98 (0.97–0.99)

< 0.001

0.98 (0.95, 1.01)

0.138

Antibiotic

 Flucloxacillin

0.62 (0.45, 0.85)

0.003

0.50 (0.21, 1.18)

0.112

 Gentamicin+

0.65 (0.47, 0.89)

0.007

 Teicoplanin+

1.54 (1.12–2.12)

0.007

Medication

 Warfarin

1.86 (0.94–3.68)

0.076

0.55 (0.08–3.69)

0.540

 Antiplatelets

1.47 (1.07–2.02)

0.018

0.65 (0.24–1.71)

0.379

 Hypoglycaemic agents

2.09 (1.30, 3.38)

0.002

1.64 (0.52, 5.16)

0.396

 Insulin

2.88 (1.06–7.83)

0.038

0.81 (0.12–5.64)

0.835

 Levothyroxine

1.73 (1.13–2.65)

0.011

1.15 (0.42–3.17)

0.790

 ACEi/ARB

2.00 (1.47, 2.71)

< 0.001

1.31 (0.60, 2.86)

0.503

 Bendrofluazide/indapamide/

1.79 (1.32, 2.44)

< 0.001

0.89 (0.41, 1.94)

0.769

  CCB/alpha blocker

   B-blocker

1.49 (1.05–2.11)

0.026

2.54 (1.00–6.46)

0.050

   Antianginals, digoxin and loop and potassium sparing diuretics

1.51 (1.02–2.25)

0.041

0.81 (0.31–2.14)

0.676

  1. Logistic regression analysis used to determine factors associated with post-operative hyponatraemia (Na < 135 mmol/L)
  2. *Adjusted for variables which showed a p-value < 0.10 in Tables 1 and 2; age, height, weight, ASA grade, peripheral nerve block, pre-operative Na, fasting glucose, pre-operative haemoglobin, flucloxacillin, warfarin, antiplatelets, hypoglycaemic agents, insulin, levothyroxine, ACEi/ARB, bendrofluazide/indapamide/CCB/alpha blocker, B-blocker and antianginals, digoxin and loop and potassium sparing diuretics
  3. +Gentamicin and teicoplanin not included in multivariate analysis due to multicollinearity. Flucloxacillin kept in multivariate analysis using stepwise backwards approach