The Danish Chiropractic Low Back Pain Cohort (ChiCo): Description and Summary of an Available Data Source for Research Collaborations

Figures & data

Figure 1 Flowchart.

Table 1 Response Times for Completed Questionnaires

Response Times	Baseline 2 (N=2029)	2 Weeks (N=1989)	3 Months (N=1705)	12 Months (N=1459)
Mean (SD); days after distribution	2.3 (3.8)	2.9 (5.3)	7.2 (10.6)	10.8 (20.5)
Median (IQR); days after distribution	1 (0–3)	1 (0–4)	3 (0–8)	4 (0–9)
Late response; n (%)*	105 (5.2%)	219 (11.0%)	78 (4.6%)	138 (9.5%)

Notes: *>7 days after distribution for baseline and 2 weeks follow-up; >1 month after distribution for 3 and 12 months follow-ups.

Table 2 Participant Characteristics

Participant Characteristics	Baseline	2 Weeks	3 Months	12 Months
Age; mean (SD, full range)	44.6 (13.7; 18–87)
Sex, female; n (%)	1167 (41.0%)
BMI; mean (SD)	26.9 (5.0)
Smoker, yes; n (%)	336 (16.2%)
Longest education:
Higher or further education; n (%)	1040 (51.5%)
Vocational education; n (%)	594 (29.4%)
No qualifying education; n (%)	313 (15.5%)
Other education; n (%)	74 (3.7%)
Employment, yes; n (%)	2287 (82.2%)
Previous treatment for low back pain, yes; n (%)	1357 (66.4%)
Previous episodes with low back pain, yes; n (%)	1652 (83.3%)
Days with low back pain within past year, >30 days; n (%)	752 (37.5%)
Episode duration:
1–7 days; n (%)	1328 (47.0%)
1 week - 3 months; n (%)	1006 (35.6%)
>3 months; n (%)	494 (17.5%)
STarT Back Tool risk groups
Low; n (%)	1211 (42.5%)
Medium; n (%)	1014 (35.6%)
High; n (%)	623 (21.9%)
Current use of over the counter and/or prescribed pain killers for back pain, yes; n (%)	1041 (51.0%)
Fear-Avoidance, FABQ Work subscale (0–42); mean (SD)	12.6 (9.4)
Days off sick within past 3 months; median (IQR)	0 (0–1)
Present sick leave, yes; n (%)	74 (4.8%)	43 (2.3%)	25 (1.3%)	20 (1.1%)
Back pain intensity, NRS (0–10); mean (SD)	6.7 (2.1)	3.7 (2.3)	2.3 (2.3)	2.3 (2.4)
Leg pain intensity, NRS (0–10); mean (SD)	3.0 (2.9)	1.9 (2.4)	1.3 (2.1)	1.1 (2.0)
Back Beliefs, BBQ (9–45); mean (SD)	32.2 (5.9)		32.8 (6.2)	32.0 (6.0)
Activity limitation, RMDQ (0–100); mean (SD)	55.0 (23.8)	30.3 (26.1)	19.7 (23.5)	20.0 (22.8)
Clinician reported working diagnosis
Non-specific LBP; n (%)	2372 (84.7%)
Back related leg pain WITHOUT nerve root involvement; n (%)	665 (23.8%)
Back related leg pain WITH nerve root involvement; n (%)	164 (5.9%)
Fracture; n (%)	14 (0.5%)
Initial suspicion of systemic pathology (Cancer, Cauda equina syndrome, Inflammatory rheumatoid arthritis, Infection)*; n (%)	31 (1.1%)

Note: *Participants not excluded because pathology not confirmed.

Table 3 Characteristics at Baseline 1 of Responders and Non-Responders to Baseline 2 and 2-Weeks Follow-Up

Patient Characteristics at Baseline*	Baseline 2		2 Weeks
	Responders (N=2083)	Non-Responders (N=765)	Responders (N=2023)	Non-Responders (N=825)
Age; mean (SD)	46.1 (13.5) (n=2083)	40.5 (13.4) (n=765)	46.6 (13.4) (n=2023)	39.6 (13.1) (n=825)
Sex, female; n (%)	918 (44.1%) (n=2083)	249 (32.6%) (n=765)	872 (43.1%) (n=2023)	295 (35.8%) (n=825)
Episode duration, >7 days; n (%)	1109 (53.6%) (n=2070)	391 (51.6%) (n=758)	1078 (53.6%) (n=2011)	422 (51.7%) (n=817)
Back pain intensity, NRS (0–10); mean (SD)	6.7 (2.0) (n=2042)	6.6 (2.2) (n=749)	6.7 (2.0) (n=1987)	6.7 (2.1) (n=804)
Leg pain intensity, NRS (0–10); mean (SD)	3.0 (2.9) (n=2039)	2.7 (2.8) (n=744)	3.0 (2.9) (n=1980)	2.9 (2.9) (n=803)
FABQ work subscale (0–42)	12.2 (9.2) (n=1715)	13.7 (10.0) (n=636)	12.2 (9.1) (n=1650)	13.7 (10.1) (n=701)
Activity limitation, RMDQ (0–100)	55.4 (23.6) (n=2083)	53.6 (24.5) (n=765)	55.0 (23.5) (n=2023)	54.8 (24.8) (n=825)
Use of medication, yes; n (%)	1041 (51.0%) (n=2043)	N/A	924 (51.4%) (n=1797)	117 (47.6%) (n=246)

Note: *All except medication are from Baseline 1.

Table 4 Baseline Characteristics of Responders to Questionnaires, Participants Interviewed and Non-Responders at 3- and 12-Month Follow-Ups

Patient Characteristics at Baseline*	3 Months			12 Months
	Responders to Questionnaires (N=1725)	Interviewed (N=201)	Non-Responders (N=922)	Responders to Questionnaires (N=1486)	Interviewed (N=329)	Non-Responders (N=1033)
Age; mean (SD)	47.3 (13.3) (n=1725)	40.6 (12.5) (n=201)	40.3 (13.4) (n=922)	47.3 (13.0) (n=1486)	41.5 (13.1) (n=329)	41.6 (14.0) (n=1033)
Sex, female; n (%)	746 (43.3%) (n=1725)	60 (29.9%) (n=201)	361 (39.2%) (n=922)	636 (42.8%) (n=1486)	124 (37.7%) (n=329)	407 (39.4%) (n=1033)
Episode duration, >7 days; n (%)	911 (53.2%) (n=1714)	108 (54.0%) (n=200)	481 (52.6%) (n=914)	787 (53.2%) (n=1478)	174 (53.2%) (n=327)	539 (52.7%) (n=1023)
Use of medication, yes; n (%)	805 (52.0%) (n=1547)	43 (43.0%) (n=100)	193 (48.7%) (n=396)	694 (51.7%) (n=1343)	98 (49.2%) (n=199)	249 (49.7%) (n=501)
Back pain intensity, NRS (0–10); mean (SD)	6.7 (2.0) (n=1695)	6.7 (2.1) (n=200)	6.7 (2.1) (n=896)	6.6 (2.0) (n=1461)	6.7 (2.1) (n=320)	6.7 (2.1) (n=1010)
Leg pain intensity, NRS (0–10); mean (SD)	3.0 (3.0) (n=1700)	3.0 (2.7) (n=194)	2.9 (2.9) (n=889)	2.9 (2.9) (n=1466)	3.1 (2.9) (n=321)	3.0 (2.9) (n=996)
FABQ work subscale (0–42)	12.0 (9.0) (n=1417)	13.4 (9.4) (n=171)	13.6 (10.2) (n=763)	11.8 (8.9) (n=1243)	14.2 (10.5) (n=260)	13.3 (9.7) (n=848)
Activity limitation, RMDQ (0–100)	54.8 (23.2) (n=1725)	56.9 (25.1) (n=201)	54.8 (24.7) (n=922)	54.7 (23.2) (n=1486)	56.0 (24.2) (n=329)	55.0 (24.6) (n=1033)

Note: *All except medication are from Baseline 1.

Table 5 Outcomes at Follow-Ups for Responders, Interviewed Participants and Non-Responders at 3- and 12-Month Follow-Ups

Patient Characteristics	3 Months			12 Months
	Responders to Questionnaires (N=1725)	Interviewed (N=201)	Non-Responders (N=922)	Responders to Questionnaires (N=1486)	Interviewed (N=329)	Non-Responders (N=1033)
Back pain intensity at 2 weeks FU, NRS (0-10); mean (SD)	3.7 (2.3) (n=1603)	3.6 (2.3) (n=85)	3.8 (2.3) (n=325)	3.7 (2.3) (n=1403)	3.9 (2.4) (n=188)	3.8 (2.3) (n=422)
Leg pain intensity at 2 weeks FU, NRS (0-10); mean (SD)	1.9 (2.4) (n=1596)	1.7 (2.1) (n=84)	2.0 (2.5) (n=325)	1.8 (2.3) (n=1395)	2.2 (2.6) (n=187)	2.0 (2.5) (n=423)
Back pain intensity at 3 months FU, NRS (0-10); mean (SD)	2.3 (2.3) (n=1718)	2.1 (2.5) (n=200)	N/A	2.3 (2.2) (n=1378)	2.3 (2.5) (n=211)	2.6 (2.4) (n=329)
Leg pain intensity at 3 months FU, NRS (0-10); mean (SD)	1.3 (2.1) (n=1717)	1.0 (2.1) (n=201)	N/A	1.3 (2.0) (n=1378)	1.2 (2.2) (n=210)	1.5 (2.2) (n=330)
Back pain intensity at 12 months FU, NRS (0-10); mean (SD)	2.3 (2.4) (n=1463)	2.0 (2.3) (n=127)	2.4 (2.5) (n=221)	2.3 (2.4) (n=1482)	2.1 (2.6) (n=329)	N/A
Leg pain intensity at 12 months FU, NRS (0-10); mean (SD)	1.1 (2.0) (n=1461)	0.8 (1.9) (n=127)	1.2 (2.1) (n=221)	1.2 (1.9) (n=1480)	0.9 (2.2) (n=329)	N/A