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Table 2 Parameter estimates from the five multilevel regression models examining the associations of LOD with individual-level and state-level variables

From: Why does the adverse effect of inappropriate MRI for LBP vary by geographic location? An exploratory analysis

ParameterLength of disability
Model 1Model 2Model 3Model 4Model 5
 Female  0.078***0.075***0.040*
Age (years)  0.005***0.005***0.005***
Tenure (years)  −0.004***−0.004***−0.004***
AWW/$100  0.017***0.013***0.013**
Industry type
 Mining  0.452***0.445***0.443***
 Construction  0.193***0.183***0.182***
 Transportation  0.258***0.247***0.247***
 Agriculture  0.0900.0830.081
 Manufacturing  0.126**0.118**0.117**
 Wholesale trade  0.0840.0760.076
 Retail trade  0.127**0.119**0.118**
 Services  0.101*0.092*0.091*
 Public administration  0.0770.0690.068
Injury severity
 More severe  0.086***0.085***0.085***
 Less severea     
Early opioid/100 mg MEA  0.014***0.014***0.014***
eMRI scan
 Yes  0.426***0.435***0.402***
Lumbar spine surgery
 Yes  0.719***0.715***0.712***
Litigation status
 Yes  1.144***1.152***1.152***
Median household income ($)  −0.007***−0.007***− 0.007***
State physician density −0.001***−0.001*− 0.001**- < 0.001
State Orthopedic surgeons density −0.0270.0700.0700.042*
MRI facility rate −0.078−0.144***− 0.129***−0.182***
Wage replacement rate 0.0020.0040.0040.004
Waiting period 0.052***0.069***0.069***0.069***
Retroactive period 0.006**0.006***0.006***0.006***
Treating provider change
 Allowed 0.234***0.115***0.109***0.114***
 Allowed once 0.001−0.118**− 0.116***− 0.114***
 Not alloweda     
Treating provider choice
 Allowed 0.165***0.270***0.261***0.332***
State medical fee schedule
 Yes 0.057*0.100***0.100***0.098***
Unemployment rate 0.024**0.013*0.012*0.011
MRI (yes) X State Orthopedic surgeons density
MRI (yes) X State Orthopedic surgeons density
MRI (yes) X Dr choice (yes)
MRI (yes) X Dr choice (no)
MRI (Yes) X male gender
MRI (Yes) X female gender
MRI (yes) X MRI facility density
MRI (no) X MRI facility density
Variance components
 Within-state variability1.393***1.390***0.914***0.910***0.910***
 Between-state variability0.072***0.035***0.026***0.025***0.025***
 Proportional reduction in between-state variability 51%64%65%65%
Random slope
 eMRI   0.011**0.011**
Model fit statistic
  1. AWW Average weekly wage, MEA Morphine equivalent amount, eMRI Early magnetic resonance imaging, ICC Intraclass correlation coefficient, −2LL −2 log likelihood ratio, BIC Bayesian information criterion
  2. *Indicator of statistical significance p<. 05; **p<. 01; ***p<. 001
  3. aIndicator of reference group