Self-reported disability according to the International Classification of Functioning, Disability and Health low back pain core set: Test-retest agreement and reliability Karl S. Bagraith, Jenny Strong, Pamela J. Meredith, Steven M. McPhail
PII: S1936-6574(17)30001-8 DOI: 10.1016/j.dhjo.2017.01.001
Reference: DHJO 560
To appear in: Disability and Health Journal Received Date: 4 September 2016
Revised Date: 22 December 2016 Accepted Date: 2 January 2017
Please cite this article as: Bagraith KS, Strong J, Meredith PJ, McPhail SM, Self-reported disability according to the International Classification of Functioning, Disability and Health low back pain core set: Test-retest agreement and reliability, Disability and Health Journal (2017), doi: 10.1016/ j.dhjo.2017.01.001.
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Brief Report
Running head: Reliability of the LBP-CS-SRC
Self-reported disability according to the International
Classification of Functioning, Disability and Health low
back pain core set: Test-retest agreement and reliability
Karl S Bagraith, B.OccThy(Hon).
a,b,c*, Jenny Strong, Ph.D.
c, Pamela J Meredith,
Ph.D.
c, and Steven M McPhail, Ph.D.
d,ea
Interdisciplinary Persistent Pain Centre, Gold Coast Hospital and Health Service, Gold Coast, Queensland, Australia.
b
Occupational Therapy Department and the Orthopaedic Physiotherapy Screening Clinic, Royal Brisbane and Women’s Hospital, Brisbane, Australia
c
Occupational Therapy, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Queensland, Australia.
d
Centre for Functioning and Health Research, Queensland Health, Brisbane, Australia
e
Institute of Health and Biomedical Innovation and School of Public Health & Social Work, Queensland University of Technology, Brisbane, Australia
* Corresponding author: Karl S Bagraith
Interdisciplinary Persistent Pain Centre, 2 Investigator Drive, Robina, Queensland, 4226, Australia.
tel.: +61 7 5668 6825; fax: +61 7 5680 9539 e-mail address: [email protected]
Abstract word count: 248 Main text word count: 2545
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Keywords: International Classification of Functioning, Disability and Health; core sets; low back
pain; reliability; agreement.
Funding: The Royal Brisbane and Women’s Hospital Foundation and the Allied Health
Professions’ Office of Queensland provided support. SMM is supported by a National Health and Medical Research Council (of Australia) fellowship. These agencies did not provide input on any aspect of the study, decision to publish, manuscript preparation or submission.
Conflicts of interest: None.
Acknowledgement: The authors are grateful to the clinicians and, in particular, the administration
officers and therapy assistants, for their assistance with data collection. The investigators appreciate the support provided by the Manager of each clinic (Darryl Lee and Louise Matthews) and the Program Manager for the statewide service (Maree Raymer). In addition, the investigators are thankful for input from Emeritus Professor Roland Sussex during the preliminary stages of this project.
Contributions: KB led the study conception and design, data collection and analysis, results
interpretation, and manuscript drafting. JS provided input on the study design and interpretation of the results. PM assisted with results interpretation. SM contributed to the data analysis and results interpretation. The manuscript was critically reviewed and approved by each author.
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Brief Report
1 2Running head: Reliability of the LBP-CS-SRC
3
4
5
Self-reported disability according to the International
6
Classification of Functioning, Disability and Health low
7
back pain core set: Test-retest agreement and reliability
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Abstract
9Background: The International Classification of Functioning, Disability and Health (ICF) Low 10
Back Pain Core Set (LBP-CS) has been proposed as a tool to facilitate the description and
11
measurement of chronic low back pain (CLBP) related disability. Patient ratings of ICF categories
12
may serve as a practical and effective method for acquiring patient input on activity limitations and
13
participation restrictions.
14
Objective: To investigate the test-retest agreement and reliability of patient ratings of activity and 15
participation according to the LBP-CS.
16
Methods: A cross-sectional repeated-measures questionnaire study was undertaken with thirty-one 17
medically stable adults with CLBP who presented for treatment at two public Australian hospitals.
18
Participants completed the LBP-CS Self-Report Checklist (LBP-CS-SRC) on two occasions (mean
19
= 12.5 (SD = 4.5) days between administrations). The LBP-CS-SRC permits patients to self-rate
20
their functioning according to the LBP-CS activity and participation categories and enables the
21
derivation of activity limitation and participation restriction scales.
22
Results: Patient ratings of individual LBP-CS categories generally exhibited good – excellent test-23
retest agreement (percentage exact agreement: 74.19 – 100.00%) and reliability (kappa: 0.53 –
24
1.00). The test-retest reliability coefficients of the LBP-CS-SRC activity (ICC = 0.94) and
25
participation (ICC = 0.90) scales were excellent. The minimum detectable change values for the
26
activity and participation scales were 8.11 and 15.26, respectively.
27
Conclusions: This study is the first to demonstrate that patients can provide reliable ratings of 28
functioning using the LBP-CS. The LBP-CS-SRC was shown to be acceptably reliable and precise
29
to support understanding of patients’ perspectives on disability in rehabilitation practice and
30
research.
31
Keywords: International Classification of Functioning, Disability and Health; core sets; low back 32
pain; reliability; agreement.
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Introduction
34Chronic low back pain (CLBP) affects approximately one in five individuals.1 People living with
35
CLBP seek to reduce activity limitations and participation restrictions when undertaking
36
rehabilitation.2 The International Classification of Functioning, Disability and Health (ICF) Low
37
Back Pain Core Set (LBP-CS), with its universally agreed upon language and framework, has been
38
proposed as a practical tool to facilitate consistent description and measurement of CLBP-related
39
functioning across different treatment settings and geographic regions.3 The LBP-CS contains 29
40
activity and participation categories that can be used to guide and evaluate multidisciplinary
41
rehabilitation.3 It is presently receiving empirical attention from a variety of perspectives to
42
understand its utility for rehabilitation research and clinical practice.4-7
43 44
Health professional ratings of LBP-CS categories are increasingly being used in clinical practice
45
and research to classify patient functioning, guide treatment, and measure outcomes.6, 8, 9 However,
46
health professionals and patients may provide quite different perspectives when quantifying
47
functioning, even when using the same instrument.10 Therefore, to gain a comprehensive
48
functioning perspective it is important to obtain patient ratings of activity and participation
49
according to the LBP-CS, in addition to those of health professionals.11
50 51
Simple patient ratings of ICF categories, akin to those provided by health professionals, may serve
52
as a practical and effective method for acquiring patient input on activity and participation.12 To
53
facilitate patient ratings of activity limitations and participation restrictions according to the
LBP-54
CS, the Low Back Pain Core Set Self-Report Checklist (LBP-CS-SRC) was developed.13 The
LBP-55
CS-SRC presents the LBP-CS categories with the modified 3-point ICF qualifier scale6, 14 to obtain
56
patients’ ratings of their activity limitations and participation restrictions. The 3-point qualifier scale
57
has been reported to function appropriately when rated by health professionals6 and patients,13 and
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is a recommended alternative to the original 5-point ICF qualifier scale.14 Psychometric analysis has
59
supported the construction of distinct measures of activity limitations and participation restrictions
60
from CLBP patients’ responses to the LBP-CS-SRC.13 The reliability of direct self-reported
61
disability according to individual LBP-CS categories has not previously been reported. Similarly,
62
whether the LBP-CS-SRC exhibits sufficient reliability for quantifying the extent of overall activity
63
limitations and participation restrictions in clinical practice and research has yet to be examined.
64
The aims of this study were to investigate: (1) the test-retest agreement and reliability of patient
65
ratings of LBP-CS activity and participation categories, and (2) the test-retest reliability, minimum
66
detectable change and feasibility of the LBP-CS-SRC activity and participation scales in patients
67
with CLBP.
68
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Methods
70Design, Participants, and Setting 71
A cross-sectional repeated measures questionnaire study was undertaken with a sample of
72
outpatients attending a multidisciplinary service that provided conservative rehabilitative
73
management of chronic musculoskeletal conditions at two public hospitals in Brisbane, Australia.
74
As part of routine practice, patients who were new to the service were mailed a letter notifying them
75
of their initial appointment details. From June – December, 2013 a study invitation letter, informed
76
consent form, and the LBP-CS-SRC were included with the aforementioned letter for eligible
77
patients. Eligibility criteria for the study were: 1) non-specific LBP15 of >3 months duration as the
78
primary reason for attendance, 2) ≥18 years of age, 3) no known cognitive deficits, and 4) able to
79
read and write English. Participants returned all completed materials on the day of their initial
80
appointment. Six days after their initial appointment, participants were mailed another clean copy of
81
the LBP-CS-SRC and invited to independently complete it, without consideration of their prior
82
ratings, and return the LBP-CS-SRC using a reply-paid envelope. The study was approved by
83
hospital (HREC/11/QPAH/08) and university (MREC/UQ/2011000604) ethics committees. Each
84
participant provided written informed consent.
85 86 Measures 87 LBP-CS-SRC 88
The LBP-CS-SRC13 is comprised of the 29 LBP-CS activity and participation second-level
89
categories, with the exception of d859 (work and employment, other specified and unspecified) due
90
to its lack of specificity, as well as 5 additional categories (d230 carrying out daily routine, d520
91
caring for body parts, d720 complex interpersonal interactions, d855 non-remunerative 92
employment, and d930 religion and spirituality) identified as potentially relevant from prior 93
empirical work.4, 5 The LBP-CS-SRC presents each ICF category label along with its associated
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examples from the ICF manual. The modified 3-point ICF qualifier scale6, 14 (0 = no difficulty, 1 =
95
some difficulty, 2 = severe difficulty/could not do, and 9 = not applicable) is utilized in the
LBP-96
CS-SRC to permit patients to self-rate activity and participation performance. Rasch analysis has
97
indicated that after the deletion of six aberrant items, the LBP-CS-SRC can also be employed as
98
distinct measures of activity limitations (17 items; scale range: 0 – 100; d230, d240, d410, d420,
99
d430, d450, d455, d460, d465, d470, d475, d520, d530, d540, d630, d640, and d650) and
100
participation restrictions (10 items; scale range: 0 – 100; d660, d710, d720, d760, d770, d845, d850,
101 d910, d920, and d930).13 102 103 Other 104
Feasibility of the LBP-CS-SRC was assessed at time one in terms of ease (interpretability, 1 = very
105
easy – 5 = very hard) and convenience (completion time, minutes) of administration. At time two,
106
participants responded to a patient global impression of change item (1 = very much improved – 7 =
107
very much worse) that assessed change in health state between LBP-CS-SRC administrations.
108 109
Data analysis 110
Test-retest agreement and reliability with adjustment for concordance due to chance were examined
111
for individual LBP-CS-SRC items using Percentage Exact Agreement (PEA) and Cohen’s nominal
112
kappa coefficient, respectively. Bootstrap resampling (1000 replications) was used to generate
113
kappa 95% confidence intervals. The Intraclass Correlation Coefficient (ICC2,1) was used to
114
quantify test-retest reliability for the LBP-CS-SRC activity and participation scales. Bland-Altman
115
plots16 (scatter plots of ‘mean of time 1 and time 2’ vs ‘difference between time 1 and time 2’ for
116
each pair of ratings) were employed to visualize whether agreement between time 1 and time 2
117
scale scores varied systematically along the measurement continua. Pearson correlation coefficients
118
(r) >|0.3| between points in the Bland-Altman plots were considered evidence of meaningful
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systematic bias.17 In addition, a paired two-tailed t-test was used to test for significant differences
120
between time 1 and time 2 scale scores. The mean LBP-CS-SRC completion time and frequency of
121
very easy/easy interpretability ratings were calculated to evaluate feasibility of administration.
122
Finally, to further inform application of the LBP-CS-SRC, the standard error of measurement
123
(SEM) and minimum detectable change (MDC95) of the activity and participation scales were
124
calculated using equations (1) and (2),18 respectively.
125 126 (1) 127 128 (2) 129 130
The guidelines proposed by Cicchetti19 were used when interpreting PEA and kappa/ICC: poor
131
(<70% and <0.40), fair (70-79% and 0.40-0.59), good (80-89% and 0.60-0.74) and excellent
(90-132
100% and 0.75-1.00). In addition, ICCs of at least 0.70 and 0.90 have been proposed as benchmarks
133
for applying instruments in research and clinical practice, respectively.20 A scale’s MDC95 was
134
considered acceptable if it was <20% of the scale’s range.21 No prior data was available to inform
a-135
priori power based sample size calculations, therefore a target sample size of 30 participants was
136
chosen based on simulation generated rule-of-thumb recommendations.22, 23 IBM SPSS (v23.0) was
137
used for analyses.
138
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Results
140Thirty-eight participants completed the LBP-CS-SRC at both time-points. Of these, seven were
141
omitted from further analyses as they either commenced treatment in-between the two
LBP-CS-142
SRC administrations or endorsed a response other than ‘no change’ on the patient global impression
143
of change item at time 2. Participants’ demographic and clinical characteristics are contained in
144
Table 1.
145 146
[Please insert Table 1 about here]
147 148
The mean (SD) time between LBP-CS-SRC administrations was 12.5 (4.5) days. PEA and kappa
149
ranged from 74.19 – 100.00% and 0.53 – 1.00, respectively (Table 2). According to Cicchetti’s
150
guidelines,19 no items exhibited poor test-retest agreement or reliability. The ICCs were 0.94
151
(95%CI: 0.88 – 0.97) and 0.90 (95%CI: 0.79 – 0.95) for the activity and participation scales,
152
respectively. The Bland-Altman plots (Fig.1) did not indicate that systematic bias was present for
153
the activity and participation scales, which was supported by the absence of meaningful correlations
154
between points (activity: r = -0.02, p = 0.90; participation: r = 0.13, p = 0.49). The mean differences
155
between time 1 and time 2 scores were -0.40 [95%CI: -1.94 – 1.14; t = -0.53; p = 0.60] and -0.37
156
[95%CI: -3.28 – 2.54; t = -0.26; p = 0.80] for the activity and participation scales, respectively.
157 158
[Please insert Table 2 about here]
159 160
[Please insert Fig.1 about here]
161 162
The SEM (MDC95) for the activity and participation scales was 2.93 (8.11) and 5.50 (15.26),
163
respectively. The LBP-CS-SRC mean (SD) completion time was 16.79 (11.09) minutes and
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participants generally considered the instrument easy to interpret (84% endorsed very easy/easy;
165
range: 1 – 3).
166
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Discussion
168To the investigators’ knowledge, this is the first study to examine the test-retest reliability of
self-169
reported disability according to the LBP-CS. Patient ratings of LBP-CS categories, via the
LBP-CS-170
SRC, generally exhibited good to excellent test-retest agreement and reliability adjusted for
171
concordance due to chance. The test-retest reliability of the LBP-CS-SRC activity and participation
172
scales was excellent. LBP-CS-SRC activity and participation scale scores were temporally stable
173
(i.e., no meaningful differences were present between administrations) and no evidence of
174
systematic measurement biases were observed between administrations. The SEM and MDC95 were
175
small, suggesting that the LBP-CS-SRC is suitably precise for measuring change over time. The
176
LBP-CS-SRC was easily interpreted by patients and its completion time was sufficiently quick to
177
support feasibility for routine application in rehabilitation practice and research.
178 179
The test-retest reliability of health professionals LBP-CS category ratings has not previously been
180
reported. However, the present results compare favorably to the inter-rater reliability observed for
181
health professionals LBP-CS ratings (i.e., >50% of activity and participation categories rated by
182
two different health professionals exhibited kappa <0.40).6 The present findings suggest that
183
patients are able to provide reliable ratings of individual LBP-CS activity and participation
184
categories. Use of LBP-CS-SRC category ratings, in addition to total scale scores, is suggested to
185
assess specific aspects of activity limitations and participation restrictions. Obtaining patient ratings
186
of LBP-CS categories via the LBP-CS-SRC may support greater integration of patients’
187
perspectives into rehabilitation practice by facilitating patient-provider communication using the
188
ICF’s common language (e.g., collaboratively developing and classifying treatment-related goals
189
according to individual activity and participation LBP-CS categories4). Employing the modified
3-190
point qualifier scale in the LBP-CS-SRC, given its recommendation for health professional
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applications,6, 14 may facilitate more straightforward utilization of patients’ LBP-CS category
192
ratings alongside those of health professionals.
193 194
The present results suggest the LBP-CS-SRC, in addition to facilitating reliable ratings of
195
individual LBP-CS categories, can be used to provide temporally stable estimates of overall activity
196
limitations and participation restrictions. The test-retest ICCs for the LBP-CS-SRC scales were
197
comparable to those of established LBP measures for analogous administration periods (e.g.,
198
Roland Morris Disability Questionnaire (RMDQ) ICC = 0.89 and Oswestry Disability Index (ODI)
199
ICC = 0.88).21 Similarly, the LBP-CS-SRC MDC95 values were superior or comparable to those of
200
the RMDQ (MDC95 = 20% of its scale range) and ODI (MDC95 = 17% of its scale range).21 These
201
comparisons suggest the LBP-CS-SRC may have utility in supporting rehabilitation practitioners to
202
obtain appropriately stable and precise estimates of overall activity limitations and participation
203
restrictions.
204 205
The LBP-CS-SRC completion time, at an average of 30 seconds/item, supports feasibility for
206
routine application in rehabilitation practice and research. The completion time is similar to reports
207
of time required for health professionals to rate LBP-CS categories (i.e., average of 37
208
seconds/item),24 which lends further support to ease of LBP-CS category interpretation by patients
209
when self-rating their functioning. Whilst the present completion time findings support routine
210
application of the LBP-CS-SRC in practice and research, short-form versions may serve as useful
211
alternatives in particularly busy settings when brevity is sought. To this end, investigations into the
212
measurement properties of LBP-CS-SRC short-forms would be a useful addition to the field.
213 214
The LBP-CS-SRC was developed to operationalize the LBP-CS with a self-report measure and
215
overcome limitations of existing patient-reported LBP disability measures.25 Current gold standard
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measures of LBP-related disability, such as the RMDQ and ODI,27 are not consistent with the
217
contemporary conceptualization of disability provided by the ICF. The RMDQ and ODI were
218
developed prior to release of the ICF and focus on the direct impact, or the interference, of pain on
219
task execution rather than actual task performance.25 In contrast, the LBP-CS-SRC assesses the
220
negative aspects of the interaction between an individual’s health condition and his/her contextual
221
factors. This difference in measurement perspective has been supported by weak correlations
222
between RMDQ items and health professional’s ratings of related LBP-CS items (e.g., patient
223
ratings of the RMDQ item ‘Because of the pain in my back, I am not doing any of the jobs that I
224
usually do around the house’ had a correlation of 0.2 with health professional’s ratings of the
LBP-225
CS category d640 housework28). Moreover, established instruments aggregate items that assess a
226
mix of ICF components, with limited coverage, into unitary scale totals.29 Therefore,
227
notwithstanding their conceptual incongruence with the ICF, it remains difficult to ascertain the
228
specific impact of interventions on activity limitations or participation restrictions when using
229
existing self-report instruments. This is in contrast to the LBP-CS-SRC, which directly and
230
distinctly measures activity limitations and participation restrictions, with evidence from this study
231
supporting its reliability as a patient-reported outcome measure. Use of the LBP-CS-SRC may
232
support rehabilitation researchers to better understand the complex interactions between CLBP and
233
contextual factors that lead to disability.30 Moreover, application of LBP-CS-SRC total scores in
234
rehabilitation research as outcome measures may afford greater insights into the differential impacts
235
of treatments on activity limitations and participation restrictions.25 Beyond rehabilitation, pending
236
further investigation, the LBP-CS-SRC could aid large scale disability surveillance programs26 or
237
even inform disability compensation decision-making.
238 239
The new methodological approach examined in the present study (i.e., direct patient ratings of ICF
240
categories) might have utility beyond the LBP-CS. Extending this present methodological approach
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to other ICF core sets may improve understanding of patient’s perspectives on disability for other
242
health conditions (e.g., obesity31). Disability measures for many health conditions, in a manner
243
similar to that noted above for LBP-specific measures, often ineffectively operationalize the ICF’s
244
disability conceptualization; for example, by aggregating items that assess a mix of components
245
into unitary scales.32 Accordingly, similar to the LBP-CS-SRC, measures derived from patients
246
ratings of other ICF core sets may serve as supplements to, or possibly replacements of, existing
247
self-report disability measures for other health conditions.
248 249
This study has several limitations. First, despite exceeding the sample size of existing LBP-CS
250
reliability analyses,6 the sample size was relatively small and further psychometric investigations
251
are suggested. Notably, however, the sample’s characteristics were consistent with those of CLBP
252
patients seeking rehabilitation,4, 6 supporting generalizability of the findings despite the sample size.
253
Second, we only considered activity and participation, given their particular amenity to
self-254
report;33 further research is required to examine the reliability of direct patient report for other ICF
255
components (e.g., environmental factors). Third, we investigated the modified 3-point ICF qualifier
256
scale and the present findings may not extrapolate to the original 5-point ICF qualifier scale. The
3-257
point ICF qualifier has been recommended6, 14 ahead of the original 5-point ICF qualifier scale,
258
which may be dysfunctional when rated by health professionals6, 7, 9, 34, 35 or patients.36
259
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Conclusion
261The present study investigated the test-retest agreement and reliability of a new methodological
262
approach for assessing self-reported disability according to the LBP-CS. The LBP-CS-SRC was
263
shown to be acceptably reliable, precise and feasible for routine application in rehabilitation
264
research and practice. Rehabilitation clinicians and researchers may consider using the
LBP-CS-265
SRC to measure disability and improve understanding of patients’ perspectives on activity
266
limitations and participation restrictions. Further examination of the LBP-CS-SRC’s measurement
267
properties appears warranted.
268 269
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Figure Legends
375 376Fig. 1. Bland-Altman plots for the Low Back Pain Core Set Self-Report Checklist activity (a) and 377
participation (b) scales. To support visualization of overlapping points, a random jitter from 0 – 1
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was applied to x-axis values. The limits of agreement for the activity and participation scales were
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-8.63 – 7.83 and -15.90 – 15.17, respectively. The Pearson correlation coefficients between ‘mean
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of time 1 and time 2’ and ‘difference between time 1 and time 2’ were -0.02 (p = 0.90) and 0.13 (p
381
= 0.49) for the activity (a) and participation (b) scales, respectively.
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Table 1Demographic and clinical variables (N=31).
Variable n (%)a
Female gender 17 (55)
Age in years , mean (SD) 53.94 (15.81)
Pain duration in months, mean (SD) 160.45 (159.48) Marital status Single 6 (19) Married 13 (43) Separated 1 (3) Divorced 5 (16) Widowed 1 (3) De facto/stable relationship 5 (16) Highest level of education
Did not complete secondary schooling 12 (39) Completed secondary schooling 8 (26) Post-secondary schooling qualification 11 (35) Employment status
Full-time 8 (26)
Part-time 2 (6)
Retired 10 (32)
Home duties 3 (10)
Unemployed due to pain 7 (23)
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General health Excellent 1 (3) Very good 1 (3) Good 13 (43) Fair 11 (35) Poor 5 (16)Average pain intensityb, mean (SD) 6.90 (1.96) Number of limiting comorbidities,
median (IQR)
2 (1)
a
Frequency count (%), unless stated otherwise.
b
11-point numerical rating scale (0 = no pain – 10 = pain as bad as you can imagine)
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Reliability of the LBP-CS-SRC Page 1 of 3
Table 2
Test-retest agreement and reliability of self-reported activity and participation according to an extended list of ICF LBP Core Set categories.
ICF code ICF label Percentage agreement Kappa
Estimate Interpretationa Estimate (95%CIb) Interpretationa
d220 Carrying out daily routine 93.55 excellent 0.88 (0.68;1.00) excellent
d240 Handling stress and other psychological demands 83.87 good 0.74 (0.51;0.94) good
d410 Changing basic body position 87.10 good 0.76 (0.54;0.94) excellent
d415 Maintaining a body position 74.19 fair 0.53 (0.25;0.75) fair
d420 Transferring oneself 87.10 good 0.72 (0.42;0.93) good
d430 Lifting and carrying objects 80.65 good 0.60 (0.32;0.85) good
d445 Hand and arm use 83.87 good 0.68 (0.42;0.88) good
d450 Walking 90.32 excellent 0.78 (0.47;1.00) excellent
d455 Moving around 90.32 excellent 0.83 (0.60;1.00) excellent
d460 Moving around in different locations 83.87 good 0.66 (0.33;0.89) good
d465 Moving around using equipment 100.00 excellent 1.00 (-;-) excellent
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Reliability of the LBP-CS-SRC Page 2 of 3
d475 Driving 90.32 excellent 0.86 (0.68;1.00) excellent
d510 Washing oneself 80.65 good 0.63 (0.34;0.84) good
d520 Caring for body parts 96.77 excellent 0.95 (0.83;1.00) excellent
d530 Toileting 87.10 good 0.74 (0.48;0.93) good
d540 Dressing 87.10 good 0.77 (0.53;0.94) excellent
d570 Looking after one’s health 100.00 excellent 1.00 (-;-) excellent
d620 Acquisition of goods and services 93.55 excellent 0.89 (0.70;1.00) excellent
d630 Preparing meals 83.87 good 0.74 (0.51;0.94) good
d640 Doing housework 93.55 excellent 0.82 (0.56;1.00) excellent
d650 Caring for household objects 90.32 excellent 0.83 (0.61;1.00) excellent
d660 Assisting others 83.87 good 0.75 (0.56;0.90) excellent
d710 Basic interpersonal interactions 93.55 excellent 0.80 (0.48;1.00) excellent
d720 Complex interpersonal interactions 87.10 good 0.67 (0.41;0.87) good
d760 Family relationships 90.32 excellent 0.77 (0.51;1.00) excellent
d770 Intimate relationships 80.65 good 0.74 (0.55;0.91) good
d845 Acquiring, keeping and terminating a job 87.10 good 0.75 (0.49;0.94) excellent
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Reliability of the LBP-CS-SRC Page 3 of 3
d855 Non-remunerative employment 90.32 excellent 0.84 (0.67;1.00) excellent
d910 Community life 83.87 good 0.78 (0.60;0.91) excellent
d920 Recreational and leisure 90.32 excellent 0.86 (0.70;1.00) excellent
d930 Religion and spirituality 93.55 excellent 0.90 (0.74;1.00) excellent
a
According to the guidelines proposed by Cicchetti, 2001. b
Bootstrapped bias-corrected confidence interval based on 1000 resamples. Where perfect agreement was present (i.e., d465 and d570) confidence intervals were not calculated.