. 2019 Nov 30;20:574. doi: 10.1186/s12891-019-2964-7

Table 2.

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

Parameter	Length of disability
Parameter	Model 1	Model 2	Model 3	Model 4	Model 5
Intercept	3.835***	3.880***	3.268***	3.269***	3.346***
Gender
Female			0.078***	0.075***	0.040*
Male^a
Age (years)			0.005***	0.005***	0.005***
Tenure (years)			−0.004***	−0.004***	−0.004***
AWW/$100			0.017***	0.013***	0.013**
Industry type
Mining			0.452***	0.445***	0.443***
Construction			0.193***	0.183***	0.182***
Transportation			0.258***	0.247***	0.247***
Agriculture			0.090	0.083	0.081
Manufacturing			0.126**	0.118**	0.117**
Wholesale trade			0.084	0.076	0.076
Retail trade			0.127**	0.119**	0.118**
Services			0.101*	0.092*	0.091*
Public administration			0.077	0.069	0.068
Finance^a
Injury severity
More severe			0.086***	0.085***	0.085***
Less severe^a
Early opioid/100 mg MEA			0.014***	0.014***	0.014***
eMRI scan
Yes			0.426***	0.435***	0.402***
No^a
Lumbar spine surgery
Yes			0.719***	0.715***	0.712***
No^a
Litigation status
Yes			1.144***	1.152***	1.152***
No^a
Median household income ($)			−0.007***	−0.007***	− 0.007***
State physician density		−0.001***	−0.001*	− 0.001**	- < 0.001
State Orthopedic surgeons density		−0.027	0.070	0.070	0.042*
MRI facility rate		−0.078	−0.144***	− 0.129***	−0.182***
Wage replacement rate		0.002	0.004	0.004	0.004
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 allowed^a
Treating provider choice
Allowed		0.165***	0.270***	0.261***	0.332***
Not-allowed^a
State medical fee schedule
Yes		0.057*	0.100***	0.100***	0.098***
No^a
Unemployment rate		0.024**	0.013*	0.012*	0.011
MRI (yes) X State Orthopedic surgeons density MRI (yes) X State Orthopedic surgeons density					0.053***
MRI (yes) X Dr choice (yes) MRI (yes) X Dr choice (no)					0.099**
MRI (Yes) X male gender MRI (Yes) X female gender					−0.047**
MRI (yes) X MRI facility density MRI (no) X MRI facility density					−0.058**
Variance components
Within-state variability	1.393***	1.390***	0.914***	0.910***	0.910***
Between-state variability	0.072***	0.035***	0.026***	0.025***	0.025***
ICC	5%	2%	3%	3%	3%
Proportional reduction in between-state variability		51%	64%	65%	65%
Random slope
eMRI				0.011**	0.011**
Model fit statistic
-2LL	188,306	188,221***	163,485***	163,323***	163,320*
BIC	188,310	188,229***	163,493***	163,342***	163,339*

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

*Indicator of statistical significance p<. 05; **p<. 01; ***p<. 001

^aIndicator of reference group