Biopsychosocial predictors of short-term success among people with low back pain referred to a physiotherapy spinal triage service

Figures & data

Table 1 Description of variables included in bivariate analysis

Category	Variable	Description and units
Sociodemographicsa	Age	<50 years; ≥50 years
	Sex	Male; female
	Symptom duration	≤6 months; >6 months
	Current episode duration	≤6 months; >6 months
	BMI	Weight (kg)/height (m^2) normal 18.5–24.9, overweight 25–29.9, grade 1 obesity 30–34.9, grade 2 obesity 35–39.9 or grade 3 obesity ≥40
	Marital status	Married; not married
	Education	≤grade 12; >grade 12
	Income	Annual household income Canadian dollars: <30 K; 30–59,999 K; 60–99,999 K; ≥100 K
	Rural residence	Urban (urban, strong or moderate MIZ); rural (weak or no MIZ)
	Farmer	yes; no
	LBP caused by work	yes; no
	Not working due to LBP	yes; no
Clinical	Comorbiditiesa	<2; ≥2
	Leg paina	Absent; above knee; below knee
	LBP triage diagnosisb	Not spine; serious spine; nerve root; non-specific LBP
	Nerve root sourceb	None; discogenic; stenotic
Treatment Recommendationsb	PT only	Physical therapy treatment recommended (without surgeon referral): yes; no
	Surgeon only	Referral to surgeon only: yes; no
	MRI/CT	MRI or CT recommendation: yes; no
	Any surgeon referral	Referral to surgeon (with or without PT referral): yes; no
	Any PT referral	Referral to PT (with or without surgeon referral): yes; no
	Any imaging	Recommendation of any imaging or other diagnostic tests
Psychologicala	FABQ_PA	Fear avoidance beliefs physical activity subscale: ≤15; >15c
	FABQ_W	Fear avoidance beliefs work subscale: ≤14; >14c
	DRAM	Distress and risk assessment measure: normal; at risk or distressed
Baseline Measuresa	Baseline NPRSc	Numeric pain rating scale: ≤5; >5
	Baseline ODQ	Oswestry Disability Questionnaire: minimal perceived disability; moderate perceived disability; severe perceived disability; crippled perceived disability
	Baseline PCSc	SF-36v2^® Physical component summary: <35; ≥35
	Baseline MCSc	SF-36v2^® Mental component summary: <48; ≥48

Notes:

a Variables derived from self-report intake questionnaire;

b variable derived from clinical classification tool;

c cutpoints derived from median values.

Abbreviations: BMI, body mass index; LBP, low back pain; PT, physiotherapy; MRI, magnetic resonance imaging; CT, computed tomography; FABQ_PA, Fear Avoidance Beliefs Questionnaire physical activity subscale; FABQ_W, Fear Avoidance Beliefs Questionnaire work subscale; DRAM, Distress and Risk Assessment Measure; NPRS, Numeric Pain Rating Scale; ODQ, Oswestry Disability Questionnaire; PCS, physical component summary; MCS, mental component summary; MIZ, metropolitan influence zone; SF-36v2^®, Medical Outcomes Survey 36-item short-form survey version 2.

Table 2 Baseline sociodemographic and health characteristics

Variable	Value (%)	N	Range
Age <50 yrs	53 (46.1)	115	20–79
Female	56 (48.7)	115
Marital status: married	86 (74.8)	115
Education: Grade 12 or less	21 (44.3)	115
Income <30 K (Canadian dollars)	20 (18.3)	109
Rural residenceb	77 (70.0)	115
Employment: full-time	62 (53.9)	115
Farmer	32 (27.8)	115
Not working due to LBP	22 (19.1)	115
LBP “caused by work”	42 (36.5)	115
Smoking status		115
Never smoked	44 (38.3)
Used to smoke	45 (39.1)
Current smoker	26 (22.6)
BMIa		115	24.4–31.6
Normal	30 (26.1)
Overweight	44 (38.3)
Grade 1 Obesity	26 (22.6)
Grade 2 Obesity	8 (7.0)
Grade 3 Obesity	7 (6.1)
Other health problems		115
Other bone or joint	72 (62.6)
Headaches	42 (36.5)
Stomach or digestive	29 (25.2)
Lung or breathing	16 (13.9)
Hypertension	14 (12.2)
Heart	12 (10.4)
Diabetes	9 (7.8)
Other	18 (15.7)
Number of other health problems		115
None	12 (10.4)
1	36 (31.3)
2	42 (36.5)
3 or more	25 (21.7)
DRAM		115
Normal	37 (32.2)
At risk	58 (50.4)
Distressed, somatic	8 (7.0)
Distressed, depressive	12 (10.4)
ODQ
Minimal (0–20)	16 (13.9)
Moderate (21–40)	60 (52.2)
Severe (41–60)	31 (27.0)
Extreme Disabilityb (61–80)	8 (7.0)

Notes:

a Combination of “weak” or “no” metropolitan area and census agglomeration influenced zones;

b BMI (kg/m²): Normal 18.5–24.9, Overweight 25–29.9, Grade 1 Obesity 30–34.9, Grade 2 Obesity 35–39.9, Grade 3 Obesity ≥40;⁸²

b there were no participants in the 80–100 category.

Abbreviations: BMI, body mass index; DRAM, Distress and Risk Assessment Method; ODQ, Oswestry Disability Questionnaire; yrs, years; LBP, low back pain.

Table 3 Baseline clinical characteristics, diagnostic classification, and triage recommendations

Variable	Value (%)	N	Range
LBP duration		114	28.5–240.0
0–6 months	15 (13.2)
7–12 months	5 (4.4)
13–24 months	8 (7.0)
>24 months	86 (74.8)
LBP current episode		115	4.0–36.0
0–6 months	46 (40.0)
7–12 months	19 (16.5)
13–24 months	18 (15.7)
>24 months	32 (27.8)
Past treatment for LBPa		115
Medication	75 (65.2)
Massage therapy	72 (62.6)
Chiropractic	69 (60.0)
Physiotherapy	63 (54.8)
Exercise therapy	39 (33.9)
Acupuncture	30 (26.1)
Surgery	4 (3.5)
Radiating leg symptoms		115
Absent	16 (13.9)
Above knee	31 (27.0)
Below knee	68 (59.1)
Diagnosisa		115
Problem in back	108 (93.9)
Medical	11 (9.6)
Mechanical/degenerative other body part	5 (4.3)
Spinal cord/cauda equina	5 (4.3)
LBP triage		115
Nerve root problem	54 (47.0)
Non-specific/mechanical spine	48 (41.7)
Serious spine pathology	8 (7.0)
Not spine related	5 (4.3)
Nerve root source		115
None	52 (45.2)
Stenotic	35 (30.4)
Discogenic	28 (24.3)
Treatment recommendationsa		115
Referral to surgeon (any)	23 (20.0)
Urgent referral to surgeon	17 (14.8)
Surgeon referral + PT treatment	6 (5.2)
Referral to another specialistb	11 (9.6)
PT treatment (any)	73 (63.5)
PT treatment (only)	67 (58.3)
Imaging and diagnostic test recommendations		115
Any imaging or other diagnostic testsc	38 (33.0)
Advanced imaging (ie, CT, MRI)	31 (27.0)
X-rays	8 (7.0)
No further follow-up	2 (1.7)	115
Other recommendationsd	7 (6.1)	115

Notes:

a Categories are not mutually exclusive;

b type of specialist: vascular, neurologist, pain management physician, urogynecologist, rheumatologist;

c includes X-ray, CT, MRI, blood work, bone scan;

d includes functional testing, chiropractic treatment.

Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; PT, physiotherapist; LBP, low back pain.

Figure 1 Proportion of participants that improved versus those that did not improve.

Abbreviations: NPRS, Numeric Pain Rating Scale; ODQ, Oswestry Disability Questionnaire; SF-36 PCS, Medical Outcomes Survey 36-item short-form; PCS, physical component summary; MCS, mental component summary.

Table 4 Proportion of participants who improved versus those who did not improve

Variable/outcome	Improved (%)	Did not improve (%)
NPRS_MIC*	12/104 (11.5)	92/104 (88.5)
ODQ_MIC*	25/108 (23.1)	83/108 (76.9)
SF-36 PCS_MIC*	52/107 (48.6)	55/107 (51.4)
SF-36 MCS_MIC*	33/107 (30.8)	74/107 (69.2)
Satisfaction	86/108 (79.6)	22/108 (20.4)

Notes:

* Based on MIC cut-points.

Abbreviations: MIC, minimal important change; NPRS, Numeric Pain Rating Scale; ODQ, Oswestry Disability Questionnaire; SF-36, Medical Outcomes Survey 36-item short-form; PCS, physical component summary; MSC, mental component summary.

Table 5 Crude and adjusted estimates for improvement in perceived pain, function, general health, and satisfaction

Variables	Crude OR	Adjusted OR	95% CI	P-value
A. Covariates of improved NPRS
Urban	2.41	3.58	(0.851, 15.056)	0.082
LBP triage: non-specific LBP (ref)	–	–
Nerve root	3.72	6.51	(0.977, 43.333)	0.058
Serious spine or not spine related	4.44	11.13	(0.918, 134.895)	0.053
ODQ: minimal (ref)	–	–
Moderate	0.31	0.14	(0.021, 0.956)	0.045
Severe	0.26	0.14	(0.016, 1.252)	0.079
Crippled	2.20	1.35	(0.158, 11.445)	0.786
B. Covariates of improved ODQ
Male	2.77	9.93	(2.202, 44.794)	0.003
LBP current episode <6 months	2.79	3.65	(0.831, 16.042)	0.086
LBP duration <6 months	3.60	7.25	(0.669, 78.605)	0.103
Smoking: Never smoked (ref)	–	–
Used to smoke	0.311	0.058	(0.010, 0.330)	0.001
Smoker	0.393	0.038	(0.005, 0.298)	0.002
Baseline PCS <35	3.75	5.95	(1.454, 24.348)	0.013
Baseline FABQ_PA >15	2.83	6.20	(1.397, 27.530)	0.016
Another specialist referral	4.94	125.26	(8.037, 1,952.163)	0.001
C. Covariates of improved PCS of SF-36
Smoking: Never smoked (ref)	–	–
Used to smoke	0.50	0.46	(0.188, 1.142)	0.094
Smoker	2.18	2.06	(0.693, 6.145)	0.193
Baseline FABQ_W >14	2.21	2.21	(1.010, 5.100)	0.047
D. Covariates of improved MCS of SF-36
Married	2.37	2.93	(0.883, 9.736)	0.079
Comorbidities <2	2.09	2.40	(0.918, 6.276)	0.074
NPRS baseline <5	3.50	4.60	(1.677, 12.591)	0.003
MCS baseline <48	3.37	5.56	(1.998, 15.458)	0.001
E. Covariates of participant satisfaction
Age <50	4.51	8.81	(2.22, 34.975)	0.002
Not married	2.98	4.17	(0.779, 22.261)	0.095
Education: grade 12 or less	2.39	4.45	(1.234, 16.013)	0.022
MRI/CT	3.73	4.11	(0.858, 19.705)	0.077
Baseline ODQ: minimal (ref)
Moderate	0.17	0.08	(0.008, 0.795)	0.031
Severe	0.35	0.15	(0.012, 1.856)	0.139
Crippled	0.07	0.02	(0.001, 0.282)	0.015
DRAM: at risk or distressed	2.27	6.65	(1.788, 24.755)	0.005

Note: Bolded values are significant at the P<0.05 level.

Abbreviations: OR, odds ratio; CI, confidence interval; NPRS, Numeric Pain Rating Scale; LBP, low back pain; ref, reference category; ODQ, Oswestry Disability Questionnaire; PCS, physical component summary; FABQ_PA, Fear Avoidance Beliefs Questionnaire physical activity subscale; FABQ_W, Fear Avoidance Beliefs Questionnaire work subscale; MCS, mental component summary; MRI, magnetic resonance imaging; CT, computed tomography; DRAM, Distress and Risk Assessment Method; SF-36, Medical Outcomes Survey 36-item short-form.

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