Complete logistic regression results according to visit

Effect	Level	1st visit model (c-statistic = 0.683)		2nd visit model (c-statistic = 0.795)		3rd visit model (c-statistic = 0.787)
		Point estimate	P	Point estimate	P	Point estimate	P
Age		1.001	0.569	0.998	0.01	0.994	0.0036
Subgroup	Subgroup II versus subgroup I	1.988	<0.0001	1.414	0.0002	2.5981	0.0002
	Subgroup III versus subgroup I	2.467		3.168		4.278
	Subgroup IV versus subgroup I	0.671		0.847		3.4774
	Subgroup Other versus subgroup I	0.794		0.77		0.6923
Age*subgroup	Age at subgroup II	0.998	0.0105	1	0.2658		0.2441
	Age at subgroup III	1.003		1.003		1.004
	Age at subgroup IV	1.017		1.015		0.9884
	Age at subgroup other	1.012		1.013		1.018
Sex	Female versus male	0.79	<0.0001	0.802	<0.0001	0.773	<0.001
First LBP is PCP or not	Yes versus no	0.676	<0.0001	0.792	<0.0001	0.594	<0.001
Charlson score		0.99	0.513	0.986	0.5221	0.958	0.0903
Smoking	Missing versus no	0.996	0.9344	0.97	0.7007	0.915	0.3212
	Quit versus no	1.217	<0.0001	1.079	0.1729	1.095	0.1504
	Yes versus no	1.384	<0.0001	1.268	<0.0001	1.254	0.0005
Alcohol	Missing versus no	1.116	0.0176	1.127	0.0853	1.032	0.6889
	Yes versus no	0.936	0.0596	0.904	0.0429	0.889	0.0403
Number of opioid Rx before LBP		1.025	0.0006	1.053	<0.0001	1.062	0.0004
First LBP visit is ED	Yes versus no	0.685	<0.0001	0.979	0.8739	1.004	0.9805
CT order at first LBP	Yes versus no	9.86	<0.0001	N/A	N/A	N/A	N/A
MRI order at first LBP	Yes versus no	4.987	<0.0001	4.14	0.0072	N/A	N/A
Other image at first LBP	Yes versus no	1.249	<0.0001	0.713	<0.0001	1.421	<0.001
Injection order at first LBP	Yes versus no	1.194	0.0599	0.775	0.0587	1.112	0.4716
Med order at first LBP	Yes versus no	1.097	0.004	0.657	<0.0001	0.753	<0.001
Lab order at first LBP	Yes versus no	0.64	<0.0001	0.373	<0.0001	0.568	<0.001
Number of visits before LBP	Yes versus no	1.003	0.0795	0.999	0.7733	1	0.8756
Fibromyalgia	Yes versus no	1.129	0.0284	1.184	0.0334	1.264	0.0091
Depression	Level 2 versus level 1	1.373	<0.0001	1.403	<0.0001	1.405	<0.001
	Level 3 versus level 1	1.164	0.756	0.742	0.6488	1.661	0.5002
	Level 4 versus level 1	1.343	<0.0001	1.285	0.0003	1.076	0.3657
	Level 5 versus level 1	1.61	<0.0001	1.491	<0.0001	1.269	0.0009
Allergic rhinitis	Yes versus no	0.897	0.007	0.842	0.0023	0.867	0.0237
Gastroesophageal reflux disease	Yes versus no	0.952	0.185	0.939	0.2287	0.882	0.0312
Arthritis	Yes versus no	1.078	0.0504	1.136	0.022	1.27	0.0002
Beta-blocker and HT	Beta-blocker order not for HT versus no beta-blocker, no HT	1.003	0.97	0.942	0.5883	1.036	0.7728
	HT without beta-blocker versus no beta-blocker, no HT	0.964	0.342	0.947	0.3351	0.831	0.0032
	Beta-blocker for HT versus no beta-blocker, no HT	0.962	0.4662	0.892	0.1256	0.892	0.1687
Physician efficiency index (/1000)		1.08	<0.0001	1.048	0.0048	1.21	<0.001
Time interval (month)		N/A	N/A	0.811	<0.0001	0.9	<0.001
Medicare	Yes versus No	1.047	0.3164	0.999	0.9854	1.006	0.9377
Workers’ Compensation	Yes versus No	1.883	<0.0001	1.481	0.0479	5.48	<0.001
Commercial insured	Yes versus No	0.88	0.0001	0.923	0.0887	1.005	0.9236

CT Computed tomography; ED Emergency department; HT Hypertension; Lab Laboratory; LBP Low back pain; Med Medical; MRI Magnetic resonance imaging; PCP Primary care physician; Rx Prescriptions