Table 2

Marginal effects of patient utilizing health care services and experiencing serious illnesses in 12-months after first provider seen for low back pain

	Early Opioid Rx		Long Opioid Rx		Had MRI/CT		Had Radiography		Had ED Visit		Had Hospitalization		Had Surgery		Had Serious Illness
	Margin	SE	Margin	SE	Margin	SE	Margin	SE	Margin	SE	Margin	SE	Margin	SE	Margin	SE
PT	3.2	0.058	1.4	0.040	16.1	0.112	11.0	0.096	16.5	0.114	7.4	0.081	2.3	0.046	22.9	0.125
Chiro	1.7	0.015	0.6	0.009	6.7	0.027	17.4	0.040	43.3	0.053	5.8	0.026	0.7	0.009	19.2	0.042
Acu	1.2	0.069	0.4	0.045	5.7	0.127	5.9	0.125	18.7	0.209	8.4	0.166	0.5	0.039	22.1	0.225
APRN	11.2	0.127	5.3	0.090	18.2	0.157	19.7	0.162	19.1	0.158	8.0	0.112	2.7	0.066	21.8	0.166
PCP	9.9	0.030	3.6	0.018	16.4	0.038	17.6	0.039	17.0	0.038	6.5	0.025	1.9	0.014	19.9	0.040
PM&R	11.1	0.073	6.3	0.055	27.4	0.111	20.5	0.101	19.3	0.096	8.7	0.067	3.7	0.047	24.6	0.103
Ortho	8.0	0.060	2.5	0.034	36.8	0.110	47.4	0.115	17.6	0.086	10.0	0.066	6.8	0.057	25.9	0.097
EM	12.6	0.109	1.9	0.048	16.7	0.126	20.6	0.134	34.5	0.154	8.6	0.096	2.0	0.048	21.7	0.140

Margins refer to the marginal effect (dy/dx) at the means reported from the second stage (probit) of a two-stage residual inclusion instrumental variable approach where the numerator (dy) is the change in outcomes as specified in the column headings and the denominator (dx) is the initial choice of provider. Models control for gender, age, co-morbidity, insurance status, rurality, county-level economic measures, and state limitations/provisions to physical therapy access. SE standard error (robust), PT physical therapist, Chiro chiropractor, ACU Acupuncturist, APRN advanced practice registered nurse, PCP primary care physicians, PM&R physical medicine and rehabilitation physician, Ortho orthopedist, EM emergency medicine physician. “Other” category results available upon request