Table 1.

Descriptive Summary of the Inception Cohort

Characteristic	No. (%)			P value
	Overall sample (N = 9547)	Missing 6-mo follow-up (n = 4314)	Completed 6-mo follow-up (n = 5233)
Patient characteristics
Age, y
18-40	2986 (31)	1282 (30)	1704 (33)	.01
41-60	3697 (39)	1717 (40)	1980 (38)
≥61	2859 (30)	1310 (30)	1549 (30)
Sex
Women	5502 (58)	2473 (57)	3029 (58)	.63
Men	4040 (42)	1836 (43)	2204 (42)
Race
White	7587 (80)	3234 (75)	4353 (83)	<.001
Black or African American	1321 (14)	712 (17)	609 (12)
Other, declined, or not availablea	634 (7)	363 (8)	271 (5)
Ethnicity
Not Hispanic or Latino	8849 (93)	3958 (92)	4891 (93)	.005
Hispanic or Latino	404 (4)	213 (5)	191 (4)
Declined or not available	289 (3)	138 (3)	151 (3)
Health insurance
Private	4888 (51)	2186 (51)	2702 (52)	.27
Medicaid	869 (9)	377 (9)	492 (9)
Medicare	1923 (20)	871 (20)	1052 (20)
Workers’ compensation, self-pay, missing, or other	1862 (20)	875 (20)	987 (19)
Body mass index b
Normal or underweight, <25	1871 (20)	772 (18)	1099 (21)	<.001
Overweight, 25 to <30	2668 (28)	1069 (25)	1599 (31)
Obesity, ≥30	3757 (39)	1449 (34)	2308 (44)
Missing or unknown	1246 (13)	1019 (24)	227 (4)
Smoking
Not current	6188 (65)	2436 (57)	3752 (72)	<.001
Current	1125 (12)	530 (12)	595 (11)
Not available	2229 (23)	1343 (31)	886 (17)
Clinical characteristics
Presenting diagnosis
Axial back pain	7111 (75)	3228 (75)	3883 (74)	.43
Back and leg pain	2431 (25)	1081 (25)	1350 (26)
SBT risk level
Low	3460 (36)	1672 (39)	1788 (34)	<.001
Medium	3783 (40)	1631 (38)	2152 (41)
High	2299 (24)	1006 (23)	1293 (25)
Baseline Oswestry Disability Index score
Minimal, 0-20	2939 (31)	1410 (33)	1529 (29)	.002
Moderate, 21-40	3364 (35)	1476 (34)	1888 (36)
Severe, 41-60	2063 (22)	880 (20)	1183 (23)
Very severe, ≥61	912 (10)	422 (10)	490 (9)
Missing or unknown	264 (3)	121 (3)	143 (3)
Psychological comorbidities
None	8973 (94)	4032 (94)	4941 (94)	.07
Depression/anxiety	569 (6)	277 (6)	292 (6)
Practice characteristics
Geographic location
UPMC	4907 (51)	2070 (48)	2837 (54)	<.001
Intermountain Healthcare	2068 (22)	663 (15)	1405 (27)
Johns Hopkins Medicine	1587 (17)	1119 (26)	468 (9)
Boston Medical Center	980 (10)	457 (11)	523 (10)
Area deprivation index quartile
1, Low deprivation	2761 (29)	1255 (29)	1506 (29)	.003
2	1764 (18)	830 (19)	934 (18)
3	2382 (25)	1001 (23)	1381 (26)
4, High deprivation	2635 (28)	1223 (28)	1412 (27)
Guideline-recommended processes of care
Pharmacologic therapies
Concordant	6925 (73)	3236 (75)	3689 (70)	<.001
Nonconcordant	2617 (27)	1073 (25)	1544 (30)
Diagnostic imaging
Concordant	7305 (77)	3317 (77)	3988 (76)	.37
Nonconcordant	2237 (23)	992 (23)	1245 (24)
Back pain subspecialty referral
Concordant	8915 (93)	4015 (93)	4900 (94)	.33
Nonconcordant	627 (7)	294 (7)	333 (6)
Nonconcordant composite
0	5152 (54)	2430 (56)	2722 (52)	<.001
1	3387 (35)	1449 (34)	1938 (37)
2	915 (10)	380 (9)	535 (10)
3	88 (1)	50 (1)	38 (1)

Abbreviations: SBT, Subgroups for Targeted Treatment Back tool; UPMC, University of Pittsburgh Medical Center.

^aOther included American Indian or Alaska Native, Asian, Hawaiian or Pacific Islander, and multirace.

^bBody mass index calculated as weight in kilograms divided by height in meters squared.