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Table 3 Adjusted mixed models for repeated measures over time

From: Impacts of injury severity on long-term outcomes following motor vehicle crashes

  Mean difference
β (95% CI)
p value Mean difference
β (95% CI)
p value Interaction p value*
PRE INJURY   12 MONTH
FOLLOW UP
  
PAID WORK
Model 1: Minimally sufficient adjustment at or before injury**      0.18
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −0.07 (−0.36, 0.22) 0.6 −0.23 (−0.59, 0.12) 0.19  
 LOS ≥7 days −0.25 (−0.66, 0.16) 0.2 −0.70 (−1.21, − 0.19) 0.007  
Model 2: Full adjustment including post-injury factors**      0.27
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −0.06 (− 0.37, 0.25) 0.7 − 0.22 (− 0.59, 0.15) 0.2  
 LOS 7+ days − 0.27 (− 0.69, 0.16) 0.2 − 0.67 (− 1.20,-0.14) 0.012  
  BASELINE
POST INJURY
  12 MONTH
FOLLOW UP
  
SF12 PCS
Model 1: Minimally sufficient adjustment at or before injury**      < 0.0001
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −8.29 (−9.40, −7.18) < 0.0001 −2.25 (−3.46, −1.04) 0.0003  
 LOS ≥7 days − 11.5 (−13.2, −9.8) < 0.0001 −8.78 (− 10.7, −6.92) < 0.0001  
Model 2: Full adjustment including post-injury factors**      < 0.0001
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −6.42 (−7.37, −5.46) < 0.0001 −0.41 (−1.56, 0.74) 0.5  
 LOS ≥7 days − 8.49 (− 9.89, − 7.09) < 0.0001 −5.64 (−7.41, −3.87) < 0.0001  
SF12 MCS
Model 1: Minimally sufficient adjustment at or before injury**      0.24
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −1.13 (−2.29, 0.03) 0.055 −1.65 (− 2.89, −0.40) 0.009  
 LOS ≥7 days −2.50 (−4.19, − 0.81) 0.0036 −3.05 (−4.96, − 1.13) 0.0018  
Model 2: Full adjustment including post-injury factors**      0.31
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days 0.18 (−0.73, 1.09) 0.69 −0.36 (− 1.48, 0.77) 0.53  
 LOS ≥7 days −0.51 (−1.83, 0.81) 0.44 −0.99 (− 2.73, 0.74) 0.26  
EQ 5D summary score
Model 1: Minimally sufficient adjustment at or before injury**      < 0.0001
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days −0.21 (− 0.25, − 0.17) < 0.0001 − 0.06 (− 0.09, − 0.02) 0.0002  
 LOS ≥7 days −0.38 (− 0.43, − 0.32) < 0.0001 −0.15 (− 0.20,-0.10) < 0.0001  
Model 2: Full adjustment including post-injury factors**      < 0.0001
 LOS ≤ 1 day Ref   Ref   
 LOS 2–6 days − 0.16 (− 0.19, − 0.12) < 0.0001 − 0.01 (− 0.04, 0.02) 0.53  
 LOS ≥7 days − 0.29 (− 0.34, − 0.24) < 0.0001 − 0.07 (− 0.11,-0.02) 0.001  
WHODAS
Model 1: Minimally sufficient adjustment at or before injury**      
 LOS ≤ 1 day   Ref   
 LOS 2–6 days   3.33 (1.13, 5.53) 0.003  
 LOS ≥7 days   13.36 (9.96, 16.8) < 0.0001  
Model 2: Full adjustment including post-injury factors**
 LOS ≤ 1 day   Ref   
 LOS 2–6 days   0.73 (−1.18, 2.64) 0.45  
 LOS ≥7 days   9.23 (6.27, 12.2) < 0.0001  
  1. Footnotes:
  2. *Interaction p value for interaction between time point and ISS category
  3. **Minimally sufficient adjustment factors for both exposure and outcome (Model 1): age, sex, crash role, perceived danger in crash, preinjury health, preinjury EQ. 5D, recruitment source
  4. Full adjustment for all factors hypothesised to underlie either exposure or outcome status (Model 2), including post-injury factors: covariates from Model 1 PLUS education, preinjury work, social satisfaction, preinjury history of anxiety or depression, pain at baseline, pain catastrophising at baseline, DASS-21 and IESR scores at baseline, and CTP claimant status.