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Table 10 Association between individual potential prognostic factors and length of stay in overall cohort

From: Patient and surgical prognostic factors for inpatient functional recovery following THA and TKA: a prospective cohort study

Potential prognostic factors rS or U, Z values
IQR LOS (nights) for groups
p value
Patient-related factors   
 Gender (0 = female, 1 = male) 14685.0, − 1.022
IQR female (4.0–5.0), IQR male (4.0–5.0)
0.31
 Age 0.20 < 0.001**
 BMI 0.06 0.29
 ASA 0.12 0.03*
 Hb − 0.03 0.54
 Living situation 0.04 0.51
 RAPT score − 0.27 < 0.001**
 Pre-op pain (VAS) 0.08 0.15
 Pre-op patient-reported general health (EQ-5D VAS) − 0.11 0.03*
 Pre-op patient-reported function (OKS/OHS) − 0.18 0.001**
 Pre-op function (mILAS) 0.20 < 0.001**
 Pre-op function (TUG) 0.26 < 0.001**
 Pre-op function (10mWT) 0.21 < 0.001**
Surgical factors   
 Arthroplasty site (0 = THA, 1 = TKA) 12065.0, − 1.996
IQR THA (3.0–5.0), IQR TKA (4.0–5.0)
0.05*
 Robot-assisted surgery (0 = no, 1 = yes) 5337.0, − 0.690
IQR no (4.0–5.0), IQR yes (3.25–5.0)
0.49
 GA only (0 = no, 1 = yes) 10172.5, − 2.769
IQR no (4.0–5.0), IQR yes (3.0–5.0)
0.006**
 GA and spinal anaesthesia (0 = no, 1 = yes) 13215.0, − 2.419
IQR no (3.0–5.0), IQR yes (4.0–5.0)
0.02*
 Sedation and spinal anaesthesia (0 = no, 1 = yes) 7972.0, − 0.373
IQR no (4.0–5.0), IQR yes (4.0–5.0)
0.71
 LIA use (0 = no, 1 = yes) 7150.0, − 2.398
IQR no (4.0–5.75), IQR yes (4.0–5.0)
0.02*
 PCA use (0 = no, 1 = yes) 9709.0, − 1.122
IQR no (4.0–5.0), IQR yes (4.0–6.0)
0.26
 Intra-articular catheter (TKA only) (0 = no, 1 = yes) 6671.0, − 0.755
IQR no (4.0–5.0), IQR yes (4.0–5.0)
0.45
 Single-shot regional block (TKA only) (0 = no, 1 = yes) 2566.5, − 1.867
IQR no (4.0–5.0), IQR yes (4.0–6.0)
0.06
 Ambulatory regional block (TKA only) (0 = no, 1 = yes) 2437.0, − 0.720
IQR no (4.0–5.0), IQR yes (3.0–5.5)
0.47
 Surgical approach (THA only) (0 = PA, 1 = DAA or DSA) 975.5, − 3.645
IQR PA (4.0–5.0), IQR DAA or DSA (3.0–4.0)
< 0.001**
 Surgery duration − 0.03 0.52
 Tourniquet duration (TKA only) − 0.02 0.94
 Tourniquet pressure (TKA only) − 0.02 0.50
Post-operative factors   
 DOS mobilisation (0 = no, 1 = yes) 10,659.0−2.443
IQR no (4.0–6.0), IQR yes (4.0–5.0)
0.02*
 Incidence of post-operative progress barriers (0 = no, 1 = yes) 8482.5, − 7.735
IQR no (3.0–4.0), IQR yes (4.0–6.0)
< 0.001**
 POD 2 mILAS 0.54 < 0.001**
 POD 2 TUG 0.31 < 0.001**
 POD 2 10mWT 0.28 < 0.001**
  1. p values were derived from Spearman’s correlation or Mann-Whitney U test, as appropriate for variable type
  2. ASA American Society of Anaesthesiologists, BMI body mass index, DAA direct anterior approach, DSA direct superior approach, DOS day of surgery, EQ-5D VAS EuroQol-5 Dimension Visual Analogue Scale, GA general anaesthesia, Hb haemaglobin, IQR inter-quartile range, LIA local infiltration analgesia, LOS length of stay, mILAS modified Iowa Level of Assistance Scale, OKS Oxford Knee Score, OHS Oxford Hip Score, PA posterior approach, PCA patient-controlled analgesia, POD post-operative day, RAPT Risk Assessment and Prediction Tool, THA total hip arthroplasty, TKA total knee arthroplasty, TUG Timed Up and Go test, VAS visual analogue scale, 10mWT ten-metre walk test
  3. *Statistical significance p < 0.05 level
  4. **Statistical significance p < 0.01 level