Risk Factors Associated With Transition From Acute to Chronic Low Back Pain in US Patients Seeking Primary Care

doi:10.1001/jamanetworkopen.2020.37371

Table 2.

Chronic Low Back Pain Status by Independent Variable for Each Risk Level and All Risk Levels Combined for Those With Completed 6-Month Follow-up

Factor Low risk (n = 1788) Medium risk (n = 2152) High risk (n = 1293) Combined risk levels (N = 5233 )
Total, No. Chronic at 6 mo, No. (%) Total, No. Chronic at 6 mo, No. (%) Total, No. Chronic at 6 mo, No. (%) Total, No. Chronic at 6 mo, No. (%)
Patient characteristics
Age, y^a
18-40 580 104 (18) 681 188 (28) 443 214 (48) 1704 506 (30)
41-60 633 124 (20) 838 284 (34) 509 249 (49) 1980 657 (33)
≥61 575 105 (18) 633 231 (36) 341 167 (49) 1549 503 (32)
Sex^a^,^b
Women 984 176 (18) 1254 429 (34) 791 421 (53) 3029 1026 (34)
Men 804 157 (20) 898 274 (31) 502 209 (42) 2204 640 (29)
Race^a^,^b^,^c
White 1503 282 (19) 1852 581 (31) 998 456 (46) 4353 1319 (30)
Black or African American 187 35 (19) 205 87 (42) 217 133 (61) 609 255 (42)
Other, declined, or not available 98 16 (16) 95 35 (37) 78 41 (53) 271 92 (34)
Ethnicity^a
Not Hispanic or Latino 1672 308 (18) 2035 662 (33) 1184 575 (49) 4891 1545 (32)
Hispanic or Latino 60 12 (20) 60 20 (33) 71 38 (54) 191 70 (37)
Declined or not available 56 13 (23) 57 21 (37) 38 17 (45) 151 51 (34)
Health insurance^a^,^b
Private insurance 965 168 (17) 1177 324 (28) 560 226 (40) 2702 718 (27)
Medicaid 370 67 (18) 457 183 (40) 225 121 (54) 1052 371 (35)
Medicare 134 45 (34) 187 89 (48) 171 108 (63) 492 242 (49)
Workers’ compensation, self-pay, missing, or other 319 53 (17) 331 107 (32) 337 175 (52) 987 335 (34)
Body mass index^a^,^b^,^d
Normal or underweight, <25 428 62 (14) 425 111 (26) 246 112 (46) 1099 285 (26)
Overweight, 25 to <30 574 104 (18) 661 195 (30) 364 155 (43) 1599 454 (28)
Obesity, ≥30 711 156 (22) 959 364 (38) 638 342 (54) 2308 862 (37)
Missing or unknown 75 11 (15) 107 33 (31) 45 21 (47) 227 65 (29)
Smoker^a^,^b
Not current 1378 245 (18) 1508 486 (32) 866 401 (46) 3752 1132 (30)
Current 138 42 (30) 229 100 (44) 228 138 (61) 595 280 (47)
Not available 272 46 (17) 415 117 (28) 199 91 (46) 886 254 (29)
Clinical characteristics
Presenting diagnosis^a^,^b
Axial back pain 1476 259 (18) 1521 463 (30) 886 409 (46) 3883 1131 (29)
Back and leg pain 312 74 (24) 631 240 (38) 407 221 (54) 1350 535 (40)
Baseline Oswestry Disability Index score^a^,^b
Minimal, 0-20 1110 192 (17) 349 78 (22) 70 23 (33) 1529 293 (19)
Moderate, 21-40 520 103 (20) 979 291 (30) 389 148 (38) 1888 542 (29)
Severe, 41-60 99 26 (26) 574 225 (39) 510 271 (53) 1183 522 (44)
Very severe, ≥61 18 3 (17) 193 81 (42) 279 166 (59) 490 250 (51)
Missing or unknown 41 9 (22) 57 28 (49) 45 22 (49) 143 59 (41)
Psychological comorbidities^b
None 1690 307 (18) 2042 656 (32) 1209 577 (48) 4941 1540 (31)
Depression/anxiety 98 26 (27) 110 47 (43) 84 53 (63) 292 126 (43)
Practice characteristics
Geographic location^a^,^b
UPMC 1047 219 (21) 1126 388 (34) 664 327 (49) 2837 934 (33)
Intermountain Healthcare 424 60 (14) 648 184 (28) 333 135 (41) 1405 379 (27)
Johns Hopkins Medicine 143 18 (13) 213 68 (32) 112 47 (42) 468 133 (28)
Boston Medical Center 174 36 (21) 165 63 (38) 184 121 (66) 523 220 (42)
Area Deprivation Index quartile^a
1, Low deprivation 529 98 (19) 595 176 (30) 382 200 (52) 1506 474 (31)
2 339 63 (19) 396 125 (32) 199 87 (44) 934 275 (29)
3 471 81 (17) 582 209 (36) 328 150 (46) 1381 440 (32)
4, High deprivation 449 91 (20) 579 193 (33) 384 193 (50) 1412 477 (34)
Guideline-recommended processes of care
Pharamcologic therapies^a^,^b
Concordant 1439 249 (17) 1405 415 (30) 845 396 (47) 3689 1060 (29)
Nonconcordant 349 84 (24) 747 288 (39) 448 234 (52) 1544 606 (39)
Diagnostic imaging^a^,^b
Concordant 1416 254 (18) 1616 500 (31) 956 465 (49) 3988 1219 (31)
Nonconcordant 372 79 (21) 536 203 (38) 337 165 (49) 1245 447 (36)
Back pain subspecialty referral^a^,^b
Concordant 1713 308 (18) 2027 634 (31) 1160 548 (47) 4900 1490 (30)
Nonconcordant 75 25 (33) 125 69 (55) 133 82 (62) 333 176 (53)
Nonconcordant composite^a^,^b
0 1106 180 (16) 1018 269 (26) 598 275 (46) 2722 724 (27)
1 572 119 (21) 877 317 (36) 489 239 (49) 1938 675 (35)
2 106 33 (31) 240 108 (45) 189 106 (56) 535 247 (46)
3 4 1 (25) 17 9 (53) 17 10 (59) 38 20 (53)

Abbreviation: UPMC, University of Pittsburgh Medical Center.
^aOverall term was significantly associated with Subgroups for Targeted Treatment Back tool risk level at P < .05.

^bOverall term was significant in a univariate logistic regression model controlling for the clustered study design of chronic low back pain status at 6 months in the combined risk levels at P < .05.

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

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

Factor	Low risk (n = 1788)		Medium risk (n = 2152)		High risk (n = 1293)		Combined risk levels (N = 5233 )
Factor	Total, No.	Chronic at 6 mo, No. (%)	Total, No.	Chronic at 6 mo, No. (%)	Total, No.	Chronic at 6 mo, No. (%)	Total, No.	Chronic at 6 mo, No. (%)
Patient characteristics
Age, y^a
18-40	580	104 (18)	681	188 (28)	443	214 (48)	1704	506 (30)
41-60	633	124 (20)	838	284 (34)	509	249 (49)	1980	657 (33)
≥61	575	105 (18)	633	231 (36)	341	167 (49)	1549	503 (32)
Sex^a^,^b
Women	984	176 (18)	1254	429 (34)	791	421 (53)	3029	1026 (34)
Men	804	157 (20)	898	274 (31)	502	209 (42)	2204	640 (29)
Race^a^,^b^,^c
White	1503	282 (19)	1852	581 (31)	998	456 (46)	4353	1319 (30)
Black or African American	187	35 (19)	205	87 (42)	217	133 (61)	609	255 (42)
Other, declined, or not available	98	16 (16)	95	35 (37)	78	41 (53)	271	92 (34)
Ethnicity^a
Not Hispanic or Latino	1672	308 (18)	2035	662 (33)	1184	575 (49)	4891	1545 (32)
Hispanic or Latino	60	12 (20)	60	20 (33)	71	38 (54)	191	70 (37)
Declined or not available	56	13 (23)	57	21 (37)	38	17 (45)	151	51 (34)
Health insurance^a^,^b
Private insurance	965	168 (17)	1177	324 (28)	560	226 (40)	2702	718 (27)
Medicaid	370	67 (18)	457	183 (40)	225	121 (54)	1052	371 (35)
Medicare	134	45 (34)	187	89 (48)	171	108 (63)	492	242 (49)
Workers’ compensation, self-pay, missing, or other	319	53 (17)	331	107 (32)	337	175 (52)	987	335 (34)
Body mass index^a^,^b^,^d
Normal or underweight, <25	428	62 (14)	425	111 (26)	246	112 (46)	1099	285 (26)
Overweight, 25 to <30	574	104 (18)	661	195 (30)	364	155 (43)	1599	454 (28)
Obesity, ≥30	711	156 (22)	959	364 (38)	638	342 (54)	2308	862 (37)
Missing or unknown	75	11 (15)	107	33 (31)	45	21 (47)	227	65 (29)
Smoker^a^,^b
Not current	1378	245 (18)	1508	486 (32)	866	401 (46)	3752	1132 (30)
Current	138	42 (30)	229	100 (44)	228	138 (61)	595	280 (47)
Not available	272	46 (17)	415	117 (28)	199	91 (46)	886	254 (29)
Clinical characteristics
Presenting diagnosis^a^,^b
Axial back pain	1476	259 (18)	1521	463 (30)	886	409 (46)	3883	1131 (29)
Back and leg pain	312	74 (24)	631	240 (38)	407	221 (54)	1350	535 (40)
Baseline Oswestry Disability Index score^a^,^b
Minimal, 0-20	1110	192 (17)	349	78 (22)	70	23 (33)	1529	293 (19)
Moderate, 21-40	520	103 (20)	979	291 (30)	389	148 (38)	1888	542 (29)
Severe, 41-60	99	26 (26)	574	225 (39)	510	271 (53)	1183	522 (44)
Very severe, ≥61	18	3 (17)	193	81 (42)	279	166 (59)	490	250 (51)
Missing or unknown	41	9 (22)	57	28 (49)	45	22 (49)	143	59 (41)
Psychological comorbidities^b
None	1690	307 (18)	2042	656 (32)	1209	577 (48)	4941	1540 (31)
Depression/anxiety	98	26 (27)	110	47 (43)	84	53 (63)	292	126 (43)
Practice characteristics
Geographic location^a^,^b
UPMC	1047	219 (21)	1126	388 (34)	664	327 (49)	2837	934 (33)
Intermountain Healthcare	424	60 (14)	648	184 (28)	333	135 (41)	1405	379 (27)
Johns Hopkins Medicine	143	18 (13)	213	68 (32)	112	47 (42)	468	133 (28)
Boston Medical Center	174	36 (21)	165	63 (38)	184	121 (66)	523	220 (42)
Area Deprivation Index quartile^a
1, Low deprivation	529	98 (19)	595	176 (30)	382	200 (52)	1506	474 (31)
2	339	63 (19)	396	125 (32)	199	87 (44)	934	275 (29)
3	471	81 (17)	582	209 (36)	328	150 (46)	1381	440 (32)
4, High deprivation	449	91 (20)	579	193 (33)	384	193 (50)	1412	477 (34)
Guideline-recommended processes of care
Pharamcologic therapies^a^,^b
Concordant	1439	249 (17)	1405	415 (30)	845	396 (47)	3689	1060 (29)
Nonconcordant	349	84 (24)	747	288 (39)	448	234 (52)	1544	606 (39)
Diagnostic imaging^a^,^b
Concordant	1416	254 (18)	1616	500 (31)	956	465 (49)	3988	1219 (31)
Nonconcordant	372	79 (21)	536	203 (38)	337	165 (49)	1245	447 (36)
Back pain subspecialty referral^a^,^b
Concordant	1713	308 (18)	2027	634 (31)	1160	548 (47)	4900	1490 (30)
Nonconcordant	75	25 (33)	125	69 (55)	133	82 (62)	333	176 (53)
Nonconcordant composite^a^,^b
0	1106	180 (16)	1018	269 (26)	598	275 (46)	2722	724 (27)
1	572	119 (21)	877	317 (36)	489	239 (49)	1938	675 (35)
2	106	33 (31)	240	108 (45)	189	106 (56)	535	247 (46)
3	4	1 (25)	17	9 (53)	17	10 (59)	38	20 (53)