Associations of Cytokine Concentrations With Key Osteopathic Lesions and Clinical Outcomes in Patients With Nonspecific Chronic Low Back Pain: Results From the OSTEOPATHIC Trial.

Article (PDF Available)inThe Journal of the American Osteopathic Association 112(9):596-605 · September 2012with26 Reads
Source: PubMed
Abstract
Little is known about the role that cytokines play in osteopathic manual treatment (OMT) of patients with chronic low back pain (LBP). To measure the baseline concentrations of interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α in patients with chronic LBP; the correlations of these cytokine concentrations with clinical measures, including the number of key osteopathic lesions; the changes in cytokine concentrations with OMT; and the association of such changes with clinical outcomes. Design: Substudy nested within a randomized controlled trial of OMT for nonspecific chronic LBP. University-based study in Dallas-Fort Worth, Texas. Seventy adult research patients with nonspecific chronic LBP. A 10-cm visual analog scale, the Roland-Morris Disability Questionnaire, and the Medical Outcomes Study Short Form-36 Health Survey were used to measure LBP severity, back-specific functioning, and general health, respectively. At baseline, IL-1β (ρ=0.33; P=.005) and IL-6 (ρ=0.32; P=.006) were each correlated with the number of key osteopathic lesions; however, only IL-6 was correlated with LBP severity (ρ=0.28; P=.02). There was a significantly greater reduction of TNF-α concentration after 12 weeks in patients who received OMT compared with patients who received sham OMT (Mann-Whitney U=251.5; P=.03). Significant associations were found between OMT and a reduced TNF-α concentration response at week 12 among patients who achieved moderate (response ratio, 2.13; 95% confidence interval [CI], 1.11-4.06; P=.006) and substantial (response ratio, 2.13; 95% CI, 1.07-4.25; P=.01) LBP improvements, and improvement in back-specific functioning (response ratio, 1.68; 95% CI, 1.04-2.71; P=.03). This study found associations between IL-1β and IL-6 concentrations and the number of key osteopathic lesions and between IL-6 and LBP severity at baseline. However, only TNF-α concentration changed significantly after 12 weeks in response to OMT. These discordant findings indicate that additional research is needed to elucidate the underlying mechanisms of action of OMT in patients with nonspecific chronic LBP.
ORIGINAL CONTRIBUTION
596 JAOAVol 112No 9 • September 2012 Licciardone et alOriginal Contribution
Associations of Cytokine Concentrations With Key Osteopathic Lesions
and Clinical Outcomes in Patients With Nonspecific Chronic Low Back
Pain: Results From the OSTEOPATHIC Trial
John C. Licciardone, DO, MS, MBA; Cathleen M. Kearns, BA; Lisa M. Hodge, PhD;
and Michael V.W. Bergamini, PhD
Context: Little is known about the role that cytokines play
in osteopathic manual treatment (OMT) of patients with
chronic low back pain (LBP).
Objective: To measure the baseline concentrations of inter-
leukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor
(TNF)-α in patients with chronic LBP; the correlations of
these cytokine concentrations with clinical measures,
including the number of key osteopathic lesions; the
changes in cytokine concentrations with OMT; and the
association of such changes with clinical outcomes.
Design: Substudy nested within a randomized controlled
trial of OMT for nonspecific chronic LBP.
Setting: University-based study in Dallas-Fort Worth,
Texas.
Patients: Seventy adult research patients with nonspecific
chronic LBP.
Main Outcome Measures: A 10-cm visual analog scale,
the Roland-Morris Disability Questionnaire, and the Med-
ical Outcomes Study Short Form-36 Health Survey were
used to measure LBP severity, back-specific functioning,
and general health, respectively.
Results: At baseline, IL-1β (ρ=0.33; P=.005) and IL-6 (ρ=0.32;
P=.006) were each correlated with the number of key osteo-
pathic lesions; however, only IL-6 was correlated with LBP
severity (ρ=0.28; P=.02). There was a significantly greater
reduction of TNF-α concentration after 12 weeks in patients
who received OMT compared with patients who received
sham OMT (Mann-Whitney U=251.5; P=.03). Significant
associations were found between OMT and a reduced
TNF-α concentration response at week 12 among patients
who achieved moderate (response ratio, 2.13; 95% confi-
dence interval [CI], 1.11-4.06; P=.006) and substantial
(response ratio, 2.13; 95% CI, 1.07-4.25; P=.01) LBP improve-
ments, and improvement in back-specific functioning
(response ratio, 1.68; 95% CI, 1.04-2.71; P=.03).
Conclusions: This study found associations between IL-
1β and IL-6 concentrations and the number of key osteo-
pathic lesions and between IL-6 and LBP severity at base-
line. However, only TNF-α concentration changed
significantly after 12 weeks in response to OMT. These
discordant findings indicate that additional research is
needed to elucidate the underlying mechanisms of action
of OMT in patients with nonspecific chronic LBP.
J Am Osteopath Assoc. 2012;112(9):596-605
O
steopathic manual treatment (OMT) is commonly
used for a variety of musculoskeletal conditions,
including low back pain (LBP). A systematic review and
meta-analysis of 6 randomized controlled trials
1-6
demon-
strated that OMT significantly reduced low back pain.
7
Subsequently, these findings led to the development and
publication of the first and only clinical practice guideline
established by the American Osteopathic Association.
8
This
guideline, which has been accepted by the Agency for
From The Osteopathic Research Center (Drs Licciardone and Hodge
and Ms Kearns), the Department of Medical Education at the Texas
College of Osteopathic Medicine (Dr Licciardone), the Department
of Molecular Biology and Immunology at the Graduate School of
Biomedical Sciences (Dr Hodge), and the Department of Pharmacology
and Neuroscience at the Graduate School of Biomedical Sciences (Dr
Bergamini), all at the University of North Texas Health Science Center
in Fort Worth. Dr Licciardone holds a master’s degree in preventive
medicine.
Dr Licciardone presented this study during The Osteopathic Research
Center’s international, interdisciplinary conference, Using Manual and
Conventional Therapies to Enhance Musculoskeletal Health, which
was held April 27 through April 29, 2012, in Fort Worth, Texas.
Financial Disclosures: None reported. This study was partially
funded by the National Institutes of Healths National Center for
Complementary and Alternative Medicine (grant no. K24AT002422),
the Osteopathic Heritage Foundation, and the American Osteopathic
Association (grant no. 09-38-599).
Address correspondence to John C. Licciardone, DO, MS, MBA,
Professor and Executive Director, The Osteopathic Research Center,
University of North Texas Health Science Center Texas College of
Osteopathic Medicine, 3500 Camp Bowie Blvd, Fort Worth, TX 76107-
2644.
E-mail: john.licciardone@unthsc.edu
Submitted March 30, 2012; revision received May 11, 2012; accepted
May 17, 2012.
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ORIGINAL CONTRIBUTION
Healthcare Research and Quality for posting on its National
Guideline Clearinghouse,
9
recommends that osteopathic
physicians use OMT in the care of patients with LBP.
During the past decade, a small, emerging body of
research has explored biomarker response to OMT for a
variety of musculoskeletal conditions. Investigations have
included nitric oxide response in blood and vasculature
following fluidic motionscomparable to manipulations”
10
;
cytokine and growth factor responses to in vitro modeling
of repetitive motion (strain) injuries and modeled
OMT
1
1-14
; endocannabinoid responses in healthy volun-
teers subjected to OMT
1
5
; and various biomarker responses
in a pilot study of OMT administered to participants with
and without chronic LBP.
1
6
Nevertheless, the American
Osteopathic Association guideline recommends further
research to elucidate mechanistically how OMT exerts its
effects in patients with LBP.
8
The present study, nested
within the OSTEOPAThic Health outcomes In Chronic
low back pain (OSTEOPATHIC) Trial,
17
assesses the asso-
ciations of cytokine concentrations with somatic dysfunc-
tion, LBP severity, back-specific functioning, and general
health, and further explores cytokine responses to OMT
in patients with chronic LBP.
Methods
The OSTEOPATHIC Trial and Overview of the Present
Study
The OSTEOPATHIC Trial and the present nested substudy
were approved by the Institutional Review Board at the
University of North Texas Health Science Center. The
OSTEOPATHIC Trial was registered with ClinicalTrials.gov
(NCT00315120) prior to enrolling research patients.
Methodologic aspects of the OSTEOPATHIC Trial have
been reported in detail elsewhere.
17
We used a randomized,
double-blind, sham-controlled, 2×2 factorial design to
study the efficacy of OMT and ultrasound therapy (UST)
in 455 patients with nonspecific chronic LBP. The present
study was nested within the OSTEOPATHIC Trial after
November 2009. Baseline cytokine measures were per-
formed using blood samples acquired from 70 patients
who consented to be part of this optional component of
the trial. Fifty-five of these patients also provided blood
samples at week 12.
Inclusion and Exclusion Criteria
Patients were adults 21 to 69 years of age, were not preg-
nant, and did not have any of the following: LBP “red
flagconditions; history of recent low back surgery, receipt
of worker’s compensation benefits or ongoing litigation
involving back problems; medical conditions that might
impede OMT or UST protocol implementation; corticos-
teroid use in the past month; or evidence of lumbar radicu-
lopathy, as determined by clinical testing for ankle dorsi-
flexion weakness, great toe extensor weakness, impaired
ankle reflexes, loss of light touch sensation in the medial,
dorsal, and lateral aspects of the foot, ipsilateral straight-
leg raising, and crossed straight-leg raising.
18
The baseline
LBP severity criterion for eligibility was calibrated over
time to optimize the spectrum of patients with chronic
LBP in the OSTEOPATHIC Trial. Originally, there was no
eligibility threshold for baseline LBP severity. However,
from November 2009 through August 2010, a baseline
visual analog scale (VAS) pain score of at least 4 of 10 cm
was required for eligibility. Thereafter, for the remainder
of the trial, the eligibility criterion was lowered to at least
2 of 10 cm. Patients were enrolled in the present study
during both periods under the prevailing eligibility crite-
rion. The impact of these eligibility criteria was that the
subset of 70 patients in the present study generally had
greater LBP severity, and both poorer back-specific func-
tioning and general health, than the overall sample of 455
patients in the OSTEOPATHIC Trial.
Baseline Somatic Dysfunction and Key Osteopathic
Lesions
Each patient received an osteopathic structural examination
prior to randomization, the methodology and results of
which have been previously reported.
19
The musculoskele-
tal table of the Outpatient Osteopathic SOAP Note Form
20
was completed as part of this examination, including an
assessment of somatic dysfunction in the thoracic 10-12,
ribs, lumbar, sacrum/pelvis, and pelvis/innominate
regions. A 4-point classification system was used to record
the severity of somatic dysfunction in each region: none,
0; mild, 1; moderate, 2; and severe, 3. Severity was deter-
mined using the TART criteria (ie, Tissue texture abnor-
mality, Asymmetry, Restriction of motion, and Tenderness).
This study focused on the presence or absence of severe
(class 3) somatic dysfunction in each anatomic region, as
represented by the descriptorskey lesion present,”sig-
nificant, symptomatic, andrestriction of motion and/or
tissue texture abnormality stands out with minimum search
or provocation.”
20
Herein, we use the descriptorkey osteo-
pathic lesion” to signify the presence of class 3 somatic
dysfunction in a given anatomic region. Thus, the total
number of anatomic regions with such key osteopathic
lesions could potentially range from 0 to 5.
Measurement of Cytokine Concentrations
Each patient in this study agreed to have blood drawn
from an antecubital vein for cytokine measurements,
including interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor
necrosis factor (TNF)-α. The pre- and posttreatment blood
samples were taken 30 minutes prior to the first treatment
session and at the week 12 exit visit, which occurred 4
weeks after the last treatment session. The venous blood
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was centrifuged at 1200g for 15 minutes at 4C. Serum
samples were then aliquoted and stored at 20C for analy-
s
is. Serum samples were either analyzed unconcentrated
or concentrated prior to testing using Centriprep centrifugal
filter units with YM-3 3000 MW filters (EMD Millipore,
Billerica, Massachusetts).
Cytokine concentrations were measured using the
commercially available Milliplex MAP human cytokine
kit (EMD Millipore, Billerica, Massachusetts). Briefly, 25
μL of serum, standard, or control were added to the appro-
priate wells. Then, 25 μL of the mixed or premixed cytokine
assay beads were added to each well. Plates were sealed
and incubated on a plate shaker overnight at 4C. Then,
plates were washed 2 times with 200 μL/well of wash
buffer, and 25 μL of detection antibodies was added to
each well. Plates were sealed and incubated on a plate
shaker for 1 hour at room temperature (2 to 2C). Then,
25 μL of streptavidin-phycoerythrin conjugate was added
to each well containing the 25 μL of detection antibodies,
and plates were sealed and incubated on a plate shaker
for 30 minutes at room temperature (20° to 25°C). Plates
were washed 2 times with 200 μL/well of wash buffer,
and 150 μL of sheath fluid was added to all wells. The
assay beads were resuspended on a plate shaker for 5 min-
utes. Plates were run on the Bio-Plex 100 System (Bio-Rad
Life Science Research, Hercules, California). The Bio-Plex
Manager software was used to determine cytokine con-
centrations from relative median fluorescent intensity
(RMFI) responses, using linear or 5-parameter logistic
curve-fitting methods. Concentrations were determined
from the cytokine standard curves extrapolated to 0 RMFI.
Cytokine concentrations determined to be at or below
0 pg/mL were recorded as 0 pg/mL.
The OMT and Sham OMT Protocols
Six OMT sessions were provided at weeks 0, 1, 2, 4, 6, and
8 using an algorithmic approach. The OMT techniques
were delivered within 15 minutes, following a standard
diagnostic evaluation
21
at each treatment session. Unless
contraindicated, treatment included high-velocity, low-
amplitude thrusts; moderate-velocity, moderate-amplitude
thrusts; soft-tissue stretching, kneading, and pressure;
myofascial stretching and release; positional treatment of
myofascial tender points; and patient isometric muscle
activation against provider unyielding and equal coun-
terforce. These techniques were primarily aimed at the
lumbosacral, iliac, and pubic regions.
Sham OMT was provided on the same timetable, was
delivered with the same constraints, and was aimed at the
same anatomic regions as active OMT. Sham OMT
involved hand contact, active and passive range of motion,
and sham techniques that simulated OMT but that used
such maneuvers as light touch, improper patient position-
ing, purposely misdirected movements, and diminished
provider force. Similar methods achieved a robust placebo
response in the North Texas Chronic Low Back Pain Trial,
6
compared with other placebo treatments for pain.
22
These
methods have been adopted by others to deliver sham
manipulation.
23
Baseline and Repeated Clinical Measures
The primary clinical outcome of interest in the OSTEO-
PATHIC Trial was LBP severity, as measured by a 10-cm
VAS.
2
4
Additionally, the Roland-Morris Disability Ques-
tionnaire (RMDQ)
2
5
and the Medical Outcomes Study
Short Form-36 Health Survey (SF-36)
2
6
were administered
to assess back-specific functioning and general health,
respectively. Outcome measures were performed prior to
treatment and periodically thereafter during the 12-week
course of study. The primary pain outcomes were assessed
at 12 weeks using response thresholds consistent with the
Initiative on Methods, Measurement, and Pain Assessment
in Clinical Trials (IMMPACT) consensus statement
27
: mod-
erate improvement in LBP (30% pain reduction from
baseline VAS score) and substantial improvement in LBP
(50% pain reduction from baseline VAS score). Such pain
reductions are highly sensitive and specific in predicting
global impression of change in patients with chronic pain.
28
A positive response for back-specific functioning was also
based on an approximate 30% improvement from base-
line,
29
which corresponded to a 2-point reduction on the
RMDQ. A 5-point elevation in the SF-36 general health
score was considered to be a clinically and socially relevant
response.
26
Statistical Analysis
Descriptive statistics were used to explore the baseline
characteristics of the 70 patients in the present study,
including their cytokine concentrations and clinical meas-
ures. The underlying distributions of the 5 cytokines
demonstrated that only the baseline TNF-α concentration
and its corresponding change over 12 weeks were nor-
mally distributed. Consequently, we relied on nonpara-
metric statistical methods for most analyses. The median
and interquartile range (IQR) were used as measures of
central tendency and dispersion, respectively. The Spear-
man rank correlation coefficient (ρ) was used to measure
correlations among the 5 cytokine concentrations (IL-1β,
IL-6, IL-8, IL-10, and TNF-α) and 4 clinical measures
(number of key osteopathic lesions, VAS pain score,
RMDQ score, and SF-36 general health score). The Mann-
Whitney U test was used to compare the OMT and sham
OMT groups with regard to changes in cytokine concen-
trations after 12 weeks. Response ratios were computed
for any cytokines with statistically significant differences
between the OMT and sham OMT groups with regard
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to change in cytokine concentrations
after 12 weeks. The response ratio was
computed as the ratio of the percentage
of patients who experienced a reduced
cytokine concentration after 12 weeks
in the OMT group as compared with
the corresponding percentage in the
sham OMT group. No analyses were
performed to assess OMT efficacy, as
this subset of 70 patients (38 in the
OMT group and 32 in the sham OMT
group) did not provide sufficient sta-
tistical power to adequately address
this issue.
1
7
The results were not adjust-
ed for concomitant UST group assign-
ments because these were randomly
distributed among the OMT and sham
OMT groups, and UST was not found
to be efficacious in preliminary analy-
ses. Database management and analy-
ses were performed with the IBM SPSS
Statistics software package (version 20;
IBM Corporation, Armonk, New York).
Hypo thesis testing was conducted at
the .05 level of statistical significance.
Results
The baseline characteristics of the 70
patients are presented in Table 1. The
median (IQR) age was 38 (23) years, and
40 patients (57%) were women. Forty-
two patients (60%) had LBP for longer
than 1 year. Relatively few patients had
been hospitalized for LBP, and none had
surgery for LBP. Thirty-nine patients
(57%) had used nonprescription drugs
for LBP in the previous 4 weeks; how-
ever, only 11 patients (16%) used pre-
scription drugs for LBP during this peri-
od. The numbers of patients declined
with increasing numbers of key osteo-
pathic lesions.
The overall and treatment group–
specific baseline cytokine concentrations
are summarized in Table 1. As shown in the Figure, baseline
concentrations for TNF-α were normally distributed. For
all other cytokines, baseline concentrations were not nor-
mally distributed (Shapiro-Wilk test, P<.001). The Spear-
man rank correlation coefficients for cytokine concentra-
tions and clinical measures are presented in Table 2. Eight
of the 10 pairwise correlations among cytokine concen-
trations achieved statistical significance. The 3 strongest
pairwise correlations were IL-1β/IL-6 (ρ=0.38; P=.001);
IL-6/IL-10 (ρ=0.37; P=.002); and IL-8/TNF-α (ρ=0.35;
P=.003). Further, IL-1β (ρ=0.33; P=.005) and IL-6 (ρ=0.32;
P=.006) concentrations were each correlated with the
number of key osteopathic lesions. Interleukin-6 concen-
tration was correlated with LBP severity (ρ=0.28; P=.02)
to a lesser degree. The strongest pairwise correlation
reflected an inverse relationship between back-specific
functioning and general health (ρ=−0.53; P<.001). There
was no statistically significant association between any
Table 1.
Baseline Patient Characteristics by Treatment Group
a
Treatment Group
Overall OMT Sham OMT
Characteristic, No. (%)
b
(n=70) (n=38) (n=32)
Age, median (IQR), y 38 (23) 37 (27) 38 (20)
Women 40 (57) 24 (63) 16 (50)
Completed College Education 28 (40) 16 (42) 12 (38)
Employed Full Time 21 (30) 13 (34) 8 (25)
M
edically Uninsured 31 (44) 15 (40) 16 (50)
C
urrent Smokers 19 (27) 10 (26) 9 (28)
C
omorbid Conditions
H
ypertension 13 (19) 8 (21) 5 (16)
D
iabetes mellitus 7 (10) 4 (11) 3 (9)
O
steoarthritis 7 (10) 3 (8) 4 (13)
D
epression 25 (36) 14 (37) 11 (34)
C
hronic LBP 1 y 42 (60) 23 (61) 19 (59)
Previously Hospitalized for LBP 5 (7) 4 (11) 1 (3)
Previously Had Surgical Procedure for LBP 0 0 0
VAS Score for LBP, median (IQR), cm
c
6.0 (2.0) 6.0 (1.9) 6.1 (2.5)
RMDQ Score, median (IQR)
d
7 (8) 7 (7) 9 (10)
SF-36 General Health Score, median (IQR)
e
67 (38) 62 (33) 72 (44)
Used Drugs for LBP in Previous 4 wk
Nonprescription 39 (56) 21 (55) 18 (56)
Prescription 11 (16) 3 (8) 8 (25)
Key Osteopathic Lesions
1 40 (57) 23 (61) 17 (53)
2 30 (43) 15 (39) 15 (47)
Cytokine Concentrations,
median (IQR), pg/mL
IL-1β 0.0 (0.4) 0.0 (0.3) 0.0 (0.5)
IL-6 0.7 (2.1) 0.8 (2.9) 0.5 (1.3)
IL-8 5.5 (4.8) 5.6 (4.4) 5.4 (5.7)
IL-10 1.3 (1.3) 1.4 (1.6) 1.3 (1.0)
TNF-α 5.7 (3.6) 5.8 (3.3) 5.4 (4.2)
a
Differences were not statistically significant.
b
Data presented as No. (%) unless otherwise indicated.
c
A 10-cm visual analog scale (VAS) was used to measure low back pain (LBP), with higher scores
indicating greater pain severity.
d
A 24-point Roland-Morris Disability Questionnaire (RMDQ) was used to measure back-specific function-
ing, with higher scores indicating greater disability.
e
A 100-point Medical Outcomes Study Short Form-36 Health Survey (SF-36) general health scale was
used to measure general health, with higher scores indicating better health.
Abbreviations: IL, interleukin; IQR, interquartile range; OMT, osteopathic manual treatment; TNF, tumor
necrosis factor.
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Figure. Distributions of concentrations for interleukin (IL)-1β (A), IL-6 (B), IL-8 (C), IL-10 (D), and tumor necrosis factor
(TNF)-α (E) at baseline for patients with nonspecific chronic low back pain (n=70). Tumor necrosis factor was the only
cytokine concentration that was normally distributed. P
<
.001 for all other distributions using the Shapiro-Wilk test.
0 50 100 150 200
80
60
4
0
20
0
A
Frequency
IL-1 Concentration, pg/mL
0 10 20 30 40
80
60
4
0
20
0
B
Frequency
IL-6 Concentration, pg/mL
0 5 10 15 20 25
80
60
40
20
0
D
Frequency
IL-10 Concentration, pg/mL
0 100 200 300 400 500 600
8
0
60
40
20
0
C
Frequency
IL-8 Concentration, pg/mL
0 2 4 6 8 10 12 14
80
60
40
20
0
Frequency
TNF- Concentration, pg/mL
E
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baseline cytokine concentration and duration of chronic
LBP.
As with baseline cytokine concentrations, only changes
in TNF-α concentrations were normally distributed
(Shapiro-Wilk test, P<.001 for changes in each other
cytokine). In contrast to 8 significant pairwise correlations
among the baseline cytokine concentrations, there were
only 3 marginally significant pairwise correlations for
changes in cytokine concentrations (IL-6/IL-10; IL-8/TNF-
α; and IL-10/TNF-α). As shown in Table 3, analysis of the
55 patients with complete pre- and posttreatment measures
of cytokine concentrations (28 patients in the OMT group
and 27 patients in the sham OMT group) demonstrated a
significantly greater reduction in TNF-α concentration in
patients who received OMT (Mann-Whitney U=251.5;
P=.03). There was no other significant difference between
the OMT and sham OMT groups with regard to change
in cytokine concentrations. Patients in the OMT group
were also more likely than patients in the sham OMT
group to have a reduced TNF-α concentration response
(response ratio, 1.52; 95% confidence interval [CI], 1.00-
2.29; P=.04) using a binary variable for reduced vs elevated
TNF-α concentration after 12 weeks.
The results of subgroup analyses for changes in TNF-α
concentration after 12 weeks are presented in Table 4.
Among patients who achieved moderate and substantial
improvements in LBP and improvement in back-specific
functioning, those who received OMT had significantly
greater TNF-α concentration reductions compared with
those who received sham OMT. These findings were
observed using both absolute change in TNF-α concen-
tration (pg/mL) and the response ratio. There was no asso-
ciation between OMT and changes in TNF-α concentration
Table 3.
Median (Interquartile Range) Changes in Cytokine
Concentrations (pg/mL) After 12 Weeks by Treatment Group
Treatment Group
OMT Sham OMT
Cytokine
(n=28) (n=27) P Value
a
IL-1β 0.00 (0.00) 0.00 (0.06) .16
IL-6 0.03 (1.43) 0.03 (0.47) .68
IL-8 0.08 (3.50) 0.08 (5.13) .82
IL-10 0.00 (0.86) 0.04 (0.86) .68
TNF-α
1.06 (2.11)
0.06 (1.90) .03
a
P values are based on the Mann-Whitney U test.
Abbreviations: IL, interleukin; OMT, osteopathic manual treatment; TNF,
tumor necrosis factor.
Table 2.
Correlations Among Cytokine Concentrations and Clinical Measures at Baseline
a
Clinical Measure
Key
Cytokine Concentration
Osteopathic VAS
SF-36 General
V
ariable IL-1
β
IL-6 IL-8 IL-10 TNF-
α
Lesions for LBP
b
RMDQ
c
Health Scale
d
C
ytokine
Concentration
IL-1β ... 0.38 (.001) 0.18 (.13) 0.31 (.01) 0.13 (.30) 0.33 (.005) 0.17 (.15) 0.11 (.34) 0.20 (.10)
I
L-6 ... ... 0.23 (.06) 0.37 (.002) 0.26 (.03) 0.32 (.006) 0.28 (.02) 0.14 (.25) 0.16 (.18)
I
L-8 ... ... ... 0.30 (.01) 0.35 (.003) 0.00 (.99) 0.10 (.42) 0.17 (.17) 0.05 (.68)
I
L-10 ... ... ... ... 0.26 (.03) 0.09 (.45) 0.06 (.65) 0.20 (.10) 0.07 (.55)
T
NF-α ... ... ... ... ... 0.15 (.22) 0.10 (.41) 0.17 (.16) 0.07 (.55)
C
linical Measure
K
ey osteopathic ... ... ... ... ... ... 0.21 (0.08) 0.08 (0.49) 0.15 (.20)
lesions
VAS for LBP
b
... ... ... ... ... ... ... 0.27 (0.02) 0.28 (.02)
RMDQ
c
... ... ... ... ... ... ... ... 0.53 (<.001)
SF-36 general ... ... ... ... ... ... ... ... ...
health scale
d
a
Correlations are reported as Spearman rank correlation coefficient (P value) for each table entry.
b
A 10-cm visual analog scale (VAS) was used to measure low back pain (LBP), with higher scores indicating greater pain severity.
c
A 24-point Roland-Morris Disability Questionnaire (RMDQ) was used to measure back-specific functioning, with higher scores indicating greater disability.
d
A 100-point Medical Outcomes Study Short Form-36 Health Survey (SF-36) general health scale was used to measure general health, with higher scores
indicating better health.
Abbreviations: IL, interleukin; TNF, tumor necrosis factor.
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among patients without improvements in LBP or back-
specific functioning, and among patients with or without
i
mprovement in general health after 12 weeks.
Comment
To our knowledge, the present study is the first to explore
the associations of cytokine concentrations with baseline
somatic dysfunction and outcomes in a clinical trial of
OMT. This setting enables a more conventional and realistic
assessment of the role of cytokines in mediating response
to OMT than previous studies, which either used labora-
tory-simulated OMT
10-14
or studied OMT in healthy par-
ticipants.
15,16
There were 3 advantages of nesting this study
within the OSTEOPATHIC Trial. First, because it has
already been shown that OMT is efficacious in reducing
LBP,
7,8
the likelihood of finding valid and statistically sig-
nificant associations of cytokine concentrations with OMT
was enhanced. Second, the randomization of patients to
OMT or sham OMT within the OSTEOPATHIC Trial min-
imized the possibility that confounders, known or
unknown, might distort the relationships among cytokine
concentrations, OMT, and clinical outcomes. Third, the
algorithmic approach to OMT provision in the OSTEO-
PATHIC Trial
1
7
facilitates future replication of our study
findings.
The most highly significant pairwise correlations
Table 4.
Overall and Subgroup Results for Changes in TNF-α Concentration After 12 Weeks by Treatment Group
Change in TNF-
α
Concentration, Reduced TNF-
α
Concentration
median (IQR), pg/mL Response, No. (%)
a
Sham P Sham Response P
Results OMT
b
OMT
c
Value
d
OMT
b
OMT
c
Ratio
e
95% CI Value
Overall Results 1.06 (2.11) 0.06 (1.90) .03 22/28 (79) 14/27 (52) 1.52 (1.00-2.29) .04
Subgroup Results According to
Clinical Response After 12 Weeks
g
Moderate improvement in LBP
Responders 1.12 (2.71) 0.47 (1.67) .003 17/20 (85) 6/15 (40) 2.13 (1.11-4.06) .006
(30% VAS pain score reduction)
Nonresponders 0.45 (3.06) 0.57 (1.72) .73 5/8 (62) 8/12 (67) 0.94 (0.48-1.83) >.99
f
(<30% VAS pain score reduction)
Substantial improvement in LBP
Responders 1.36 (2.86) 0.41 (2.91) .005 16/18 (89) 5/12 (42) 2.13 (1.07-4.25) .01
f
(50% VAS pain score reduction)
Nonresponders 0.45 (2.74) 0.42 (1.66) .85 6/10 (60) 9/15 (60) 1.00 (0.52-1.92) >.99
f
(<50% VAS pain score reduction)
Improvement in back-specific
functioning
Responders 1.12 (2.20) 0.06 (1.75) .007 16/18 (89) 9/17 (53) 1.68 (1.04-2.71) .03
f
(2 point RMDQ score reduction)
Nonresponders 0.53 (3.21) 0.13 (1.90) .91 6/10 (60) 5/10 (50) 1.20 (0.54-2.67) >.99
f
(<2 point RMDQ score reduction)
Improvement in general health
Responders 1.10 (1.62) 0.47 (1.60) .14 14/17 (82) 7/12 (58) 1.41 (0.83-2.39) .22
f
(5 point SF-36 score elevation)
Nonresponders 0.84 (4.50) 0.15 (2.35) .13 8/11 (73) 7/15 (47) 1.56 (0.81-2.99) .25
f
(<5 point SF-36 score elevation)
a
Within each treatment group, the first table entry is the number of patients who had a reduced tumor necrosis factor (TNF)-α concentration at week 12 compared
with baseline. The second entry is the number of patients who were included in the subgroup analysis. The percentage of patients in the subgroup with a reduced
TNF-α concentration response is included in parentheses.
b
n=28
c
n=27
d
P values are based on the Mann-Whitney U test.
e
Response ratios are for the osteopathic manual treatment (OMT) group relative to the sham OMT group.
f
P values are based on the Fisher exact test (2-sided).
g
A 10-cm visual analog scale (VAS) was used to measure low back pain (LBP), with higher scores indicating greater pain severity; a 24-point Roland-Morris Disability
Questionnaire (RMDQ) was used to measure back-specific functioning, with higher scores indicating greater disability; and a 100-point Medical Outcomes Study
Short Form-36 Health Survey (SF-36) general health scale was used to measure general health, with higher scores indicating better health.
Abbreviations: CI, confidence interval; IQR, interquartile range.
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JAOA Vol 112 • No 9 • September 2012 603Licciardone et al • Original Contribution
ORIGINAL CONTRIBUTION
a
mong baseline cytokine concentrations (IL-1β/IL-6; IL-
6/IL-10; and IL-8/TNF-α) that we observed in our patients
with chronic LBP were consistent with correlations of
cytokine concentration reported in asymptomatic persons.
30
There were significant correlations between the concen-
trations of both IL-1β and IL-6 and severe somatic dys-
function, as manifested by the presence of key osteopathic
lesions. Additionally, IL-6 concentration was correlated to
a lesser degree with LBP severity. However, the only change
in cytokine concentration after 12 weeks that was associated
with OMT was a reduction in TNF-α. This change was
most evident in patients who achieved clinical responses,
as manifested by improvements in LBP severity and back-
specific functioning. Thus, the discordant findings for
cytokine concentrations and their associations with key
osteopathic lesions, LBP severity, and OMT raise additional
questions for future research.
The pathophysiology of LBP has been studied in
patients with intervertebral disk degeneration and herni-
ation. Although the relationship between disk degeneration
and LBP is not clearly understood, it appears that IL-1 and
TNF-α may be responsible for local chemical mediation
of pain by promoting matrix degradation by means of
enhanced production of matrix metalloproteinases.
31
Con-
sequently, IL-1β and TNF-α may be associated with non-
specificchronic LBP when such degenerative changes
are present at a subclinical level. It is also believed that IL-
1, IL-6, and TNF-α induce and enhance the expression of
matrix metalloproteinases, leading to regression of a her-
niated intervertebral disk.
31
Thus, this belief provides anoth-
er possible explanation for the presence of inflammatory
cytokines in patients with “nonspecific” chronic LBP. It
also provides a rationale for the significant pairwise cor-
relations that we observed between baseline concentrations
of both IL-1β and IL-6 and the number of key osteopathic
lesions.
A cross-sectional study
32
of 23 patients with chronic
LBP attributed to herniated intervertebral disks and 10
healthy controls found significantly increased concentra-
tions of IL-6 and TNF-α, but not of IL-1β, in patients with
LBP. Another study
33
of 94 patients with chronic neuro-
pathic, nociceptive, or mixed pain for greater than 6 months
and 6 healthy controls found a dose-response relationship
between increasing cytokine concentrations (including
IL-1β, IL-6, and TNF-α) and increasing pain severity.
Tumor necrosis factor-α was evaluated in a longitu-
dinal study of 120 patients with LBP and 120 matched
healthy controls.
34
This study had several methodologic
features that were similar to the features in our study,
including patients with nonspecific chronic LBP, exposure
to a treatment regimen, and several months of follow-up
using a VAS for LBP and the RMDQ. At baseline, 58% of
LBP patients were considered positive for TNF-α (serum
T
NF-α concentration >2 pg/mL) vs 12% of healthy con-
trols. The percentage of TNF-α positives declined after 10
days of treatment and then remained stable for 6 months,
whereas the percentage of TNF-α positives among controls
remained stable throughout the entire study. Although
VAS pain and RMDQ scores also declined over time, the
change in TNF-α concentration was not predictive of clinical
outcomes in the LBP patients. Our subgroup analyses
found that the reduction in TNF-α concentration with
OMT was indeed associated with improvements in LBP
and back-specific functioning.
It has been known for more than 2 decades that periph-
eral immune challenges lead to the activation of discrete
circuitries within the central nervous system via both
hematogenous and neural pathways, thereby facilitating
changes known as sickness responses.
35
Cytokines are sick-
ness-inducing agents that facilitate pain by creating a well-
defined immune-to-brain-to-spinal cord pathway, in which
the ventrolateral medulla-to-spinal cord limb of the path-
way leads to release of neurotransmitters or neuromodu-
lators that activate spinal cord glia and enhance pain.
35
Such pain facilitation is preventable by blocking the actions
of cytokines, including TNF-α.
36
Two TNF-α inhibitors,
infliximab
37
and etanercept,
38
each yielded encouraging
results in open-label studies involving disk-related sciatica.
A recent randomized controlled trial
39
found significantly
better pain outcomes in patients with sciatica 4 weeks after
the epidural administration of etanercept, compared with
those who received dexamethasone. However, a blinded,
placebo-controlled trial found no significant clinical benefits
52 weeks after a single intravenous infusion of infliximab.
40
On the basis of our findings, it is reasonable to hypothesize
that OMT may serve to effectively reduce serum TNF-α
concentration and thereby alleviate pain in patients with
nonspecific chronic LBP. More research on this hypothesis
appears warranted, given the safety and potential cost
advantages of OMT relative to commercially available
TNF-α inhibitors.
Despite the strengths of nesting this study within a
randomized controlled trial, there are potential limitations
of our study. First, because the analyses involved 5
cytokines and 4 clinical measures, it is possible that some
significant findings may represent type I errors because
of these multiple comparisons. Nevertheless, because we
desired to generate hypotheses for future testing within
this exploratory study, we elected not to adjust for multiple
comparisons. Second, and conversely, type II errors may
have occurred because only 15% of OSTEOPATHIC Trial
patients had pretreatment cytokine measures and 12% had
matched posttreatment measures. Although there were
several significant findings in this study, it is possible that
other important associations may have been missed
because of limited sample size. Third, cytokine concentra-
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tions may vary diurnally or because of other confounders,
such as medication use, that were not tightly controlled
in our study. Generally, we believe that the randomization
process would have mitigated such potential confounders
by allocating them comparably between the OMT and
sham OMT groups. The matching of patient pre- and post-
treatment cytokine measures further diminished the poten-
tial for confounding bias.
Conclusion
The discordant findings in our study indicate that more
research is needed to elucidate the underlying mechanisms
of action of OMT in patients with nonspecific chronic LBP.
Interleukin-1β, IL-6, and TNF-α are candidate cytokines
that warrant additional research.
Acknowledgments
The authors thank the research personnel at The Osteopathic
Research Center and the patients for their contributions to this
study.
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