Pain. 2018 (Jul); 159 (7): 1297–1307 ~ FULL TEXT
Roni Evans, Mitchell Haas, Craig Schulz, Brent Leininger, Linda Hanson, and Gert Bronfort
Integrative Health & Wellbeing Research Program,
Earl E. Bakken Center for Spirituality and Healing,
University of Minnesota,
Minneapolis, MN, USA.
Low back pain (LBP) is common in adolescence, but there is a paucity of high-quality research to inform care. We conducted a multicenter randomized trial comparing 12 weeks of spinal manipulative therapy (SMT) combined with exercise therapy (ET) to ET alone.
Participants were 185 adolescents aged 12 to 18 years with chronic LBP.
The primary outcome was LBP severity at 12, 26, and 52 weeks. Secondary outcomes included disability, quality of life, medication use, patient- and caregiver-rated improvement, and satisfaction. Outcomes were analyzed using longitudinal linear mixed effect models. An omnibus test assessing differences in individual outcomes over the entire year controlled for multiplicity.
Of the 185 enrolled patients, 179 (97%) provided data at 12 weeks and 174 (94%) at 26 and 52 weeks. Adding SMT to ET resulted in a larger reduction in LBP severity over the course of 1 year (P = 0.007). The group difference in LBP severity (0–10 scale) was small at the end of treatment (mean difference = 0.5; P = 0.08) but was larger at weeks 26 (mean difference = 1.1; P = 0.001) and 52 (mean difference = 0.8; P = 0.009). At 26 weeks, SMT with ET performed better than ET alone for disability (P = 0.04) and improvement (P = 0.02). The SMT with ET group reported significantly greater satisfaction with care at all time points (P ≤ 0.02). There were no serious treatment-related adverse events.
For adolescents with chronic LBP, spinal manipulation combined with exercise was more effective than exercise alone over a 1–year period, with the largest differences occurring at 6 months. These findings warrant replication and evaluation of cost effectiveness.
ClinicalTrials.gov Identifier: NCT01096628
From the Full-Text Article:
The United States is in the midst of an unprecedented pain management crisis, with
chronic pain impacting over ⅓ of the US population, and affecting more individuals than
heart disease, diabetes, and cancer combined.  LBP is one of the most common and
burdensome of the pain conditions with an estimated 40–80% of individuals worldwide
experiencing LBP at some point in their lives. [25, 31] LBP related disability has
increased an alarming 42% over the past two decades, making it the leading cause of
disability globally.  While there has been a long-standing belief that LBP is limited to
adults, there is now substantial evidence to the contrary. In fact, research has shown
that LBP develops with increasing frequency in adolescence, with prevalence rates
reaching that of adults by the late teens. [10, 33, 34, 37] Importantly, adolescent LBP has
been shown to be a strong predictor of adult LBP, which may have important negative
implications for the lifetime course. [17, 28, 33]
An additional concern is that 20%–40% of
U.S. adolescent LBP sufferers receive an opioid prescription when they seek medical
care. [24, 51] There is a heightened urgency to identify safe and effective nonpharmacological
LBP treatments for all ages. 
In 2012, complementary healthcare approaches were used by one third of American
adults  and 12% of children 4–17.  Spinal manipulative therapy (SMT) is the most
common provider based complementary approach [4, 13] and is often used to treat LBP
complaints. SMT consists of manual techniques including high velocity, low amplitude
thrust procedures or low velocity, variable amplitude mobilization maneuvers. For LBP,
SMT is applied to the lumbar vertebral or sacroiliac joints with the aim of restoring
mobility and decreasing pain.  Recent guidelines for LBP in adults strongly
recommended SMT as well as exercise prior to initiating pharmacologic treatment. 
Rehabilitative exercise focused on teaching and encouraging patients how to manage
their LBP, and potentially prevent future recurrences, is frequently combined with SMT
as an important aspect of promoting patient self-efficacy. 
While there is fairly well established evidence regarding the effectiveness of commonly
used conservative treatments like supervised exercise and SMT for adults with chronic
LBP, [12, 52] there are few randomized trials focusing on adolescents with LBP. [10, 44]
Indeed, a systematic review of conservative treatments for LBP in children and
adolescents was unable to locate any trials focused on SMT, and only three small
studies [1, 20, 35] focused on exercise. Thus there is a critical need for more high quality
RCTs to inform the responsible management of LBP in non-adult populations. 
To address the large research gaps for LBP management in adolescents, we performed
a parallel-group, randomized controlled trial to test the comparative effectiveness of SMT
plus exercise therapy (ET) versus ET alone for individuals 12–18 years of age with
recurrent or chronic LBP. We chose exercise alone as a comparison intervention
because of the encouraging preliminary evidence of effectiveness for adolescents with
LBP and the potential to promote active pain coping behaviors. The primary aim of
this study was to test the hypothesis that the addition of SMT to exercise would be more
effective than exercise alone at 12, 26, and 52 weeks in improving LBP pain severity.
The impact on other important LBP related outcomes, including disability, quality of life,
medication use, patient and caregiver-rated improvement and satisfaction, was also
A detailed description of the full study protocol was published previously.  The study
was funded by the U.S. Department of Health and Human Services and was registered
at clinicaltrials.gov (NCT01096628) This was a two-site, parallel-group randomized
controlled trial that used allocation by rank-order minimization. Participants were
recruited from March 2010 to December 2012, with follow-up data collection through
December 2013. Institutional Review Boards at participating institutions (Northwestern
Health Sciences University and University of Western States) approved the study
protocol. Written patient assent and parent consent were obtained for participants 12–17
years of age and written consent was provided by participants who were 18 years of
age. Primary and secondary outcomes were mostly self-reported, with the exception of
blinded objective measures of spinal function and activity levels; all outcomes were
collected independent of investigator influence. A Data Safety and Monitoring Board
consisting of a medical physician, health services research scientist, and a statistician
monitored the study.
Setting and participants
Study participants were recruited mainly from the general population using direct mail
postcards, social media, paper and digital advertisements. Letters were also sent to local
physicians and sport coaches requesting referrals. Screening, intervention and data
collection took place at two clinical research centers in Minneapolis, Minnesota and
Portland, Oregon. Interested parties were screened for eligibility initially by phone and at
three subsequent in-person baseline evaluations. Inclusion criteria were: adolescents
(12–18 years of age) with sub-acute recurrent or chronic, non-specific LBP (severity
3/10) with or without leg pain. Sub-acute recurrent LBP was defined as a current episode
of 2–12 weeks duration with a history of at least one additional two-week episode of back
pain in the past year. Chronic LBP was defined as duration of the current episode of ≥
12 weeks. Participants were allowed to use over-the-counter medication as needed.
Exclusion criteria were: SMT, ET, or changes in prescription pain medications within the
past month, other concurrent provider-based treatment for LBP, contraindications to
study treatment (e.g. clinical spinal instability, inflammatory arthropathies, etc.), benign
joint hypermobility syndrome, and other serious physical or mental health conditions as
determined by self-report and clinical exam and history.
Assignment to study intervention was performed using a computerized dynamic
allocation (rank-order minimization) system to balance participant characteristics of
gender, age, LBP duration and severity between groups at each study site using a 1:1
allocation ratio. The first six participants at each site were randomly assigned using a
computer-generated random allocation sequence secured in sealed, opaque,
sequentially numbered envelopes to seed the dynamic allocation system.
Randomization envelopes were also used as a backup if the dynamic allocation system
was not available (e.g., internet service disruption). Allocation was concealed from
investigators and all study personnel. The allocation program and envelopes were
prepared by the study statistician prior to commencing enrollment independent of
All study personnel were trained and certified to implement study protocols in an effort to
ensure standardization within and across sites. Blinding of participants and treatment
providers was not possible due to the physical nature of the interventions. The
intervention period was 12 weeks. Chiropractors and exercise therapists were trained to
deliver ET to both study groups. ET and SMT could have occurred in either order ie. ET
either before or after SMT using protocols that our group has applied in previous studies
of adults. [7, 8] Detailed descriptions of the interventions are provided in a previous
Exercise therapy (ET)
The goal of the ET program was to help adolescents manage their LBP and prevent
future occurrences. The ET program included self-care education, supervised exercise
and instructions for home exercise. Participants attended 8–16, 45 minute sessions with
an exercise therapist or licensed chiropractor no more than 2 times per week.
Treatment dose was determined based on patients’ abilities and needs. Self-care
education included patient-centered goal setting and emphasis on the importance of
movement and activity, pain management, and spinal posture awareness with basic
activities of daily living (e.g., sitting, getting out of bed and using a backpack).
Participants were also provided printed instructions and photos for each exercise, along
with a modified Back in Action book.  Each supervised exercise session began with a
5 minute light aerobic warm-up followed by stretching and strengthening exercises
(bridge, abdominal crunches, quadruped, side bridge and back extensions). Participants
began with exercises appropriate for their fitness level and progressed in difficulty by
changing body position and/or labile surface (i.e. gym ball). They were provided
instructions to perform the same exercises at home and to engage in 20–40 minutes of
aerobic activity twice per week.
Spinal manipulation combined with exercise therapy (SMT+ET)
The goal of the combined SMT+ ET program was to enhance patients’ ability to exercise
by providing treatment to the lumbar vertebral or sacroiliac joints in an effort to increase
mobility and decrease pain.  Participants attended 8–16, 10–20 minute study visits
with experienced licensed chiropractors, no more than 2 times per week. SMT visits took
place on the same day as ET sessions when possible, and could take place either
before or after ET sessions. SMT dose, spinal levels treated, and technique were
individualized to the patient based on the patient’s prognosis, tolerance, and needs. A
brief updated history and examination were conducted at each visit. High-velocity, low
amplitude SMT was the preferred technique; however, low-velocity low amplitude SMT,
mobilization, flexion-distraction manipulation, or drop-table assisted SMT could also be
used. Up to a few minutes of ice or heat or light soft tissue massage were allowed to
facilitate the SMT, if necessary. Participants in the SMT+ET group took part in the same
exercise therapy program described above.
Participant demographic and clinical characteristics were collected during the baseline
visits via a comprehensive health history and physical examination and self-report
questionnaires. Self-reported outcomes were collected at the first two baseline visits and
at 4, 8, 12, 26, and 52 weeks post-enrollment using questionnaires administered
independent of staff or clinician influence. Parent-reported outcomes were collected by
questionnaires at 12, 26, and 52 weeks. Objective biomechanical outcomes were
collected at baseline, 12, and 26 weeks post enrollment by examiners blinded to
treatment assignment and independent of investigator influence. Individual qualitative
interviews were also performed at 12 weeks exploring participants’ perspectives.
The primary outcome was self-reported typical level of LBP severity over the past week
measured with the 11–box numerical rating scale (0= no pain, 10 = worst pain possible).
The 11–box numerical rating scale performs similarly to the visual analogue scale in
adult and pediatric populations. [30, 59]
Secondary measures included patient-rated disability (18–item Roland-Morris Disability
Questionnaire), [40, 55] quality of life (23–item PedsQL), [36, 56–58] improvement (9–point
scale ranging from no symptoms,100% improvement, to as bad as it could be, 100%
worse),  frequency of medication use for low back pain (days/week), and patient
satisfaction with care (7–point scale, 1=completely satisfied, couldn’t be better,
7=completely dissatisfied, couldn’t be worse).  Healthcare utilization and home
exercise compliance were also ascertained. Side effects and adverse events were
queried on the self-report questionnaires using a list of expected events informed by
past studies. [8, 41] Participants rated each adverse event using an 11–point
bothersomeness scale (0 = not at all bothersome, 10 = extremely bothersome). Further,
participants were asked about any new or persisting events at each treatment visit.
Parents/guardians were asked to rate their perception of the participating adolescent’s
improvement and satisfaction with care. In addition, the participant’s expectation of 3–
month improvement was assessed once immediately following treatment allocation
using the same 9–point improvement scale listed above.
The sample size calculation was based on the ability to detect an 8–percentage point
mean difference in the primary outcome (LBP severity) at 12, 26, and 52 weeks.
Assuming a SD of 1.4, based on a prior study within an adolescent LBP population, 
and allowing for an attrition rate of 15%, 92 participants per group (184 total) were
required to ensure 92% power at an alpha level of 0.01.
We used an intention-to-treat approach, analyzing all observed data from participants
according to their allocated treatment assignment. Data analyses were performed in
STATA, version 13.0 (StataCorp. 2013. Stata Statistical Software: Release 13. College
Station, TX: StataCorp LP). The statistician was blinded to group allocation for all
All primary and secondary outcomes were analyzed using linear mixed effect models
including fixed effects for time, treatment, and a time-by-treatment interaction, and a
random intercept to account for within-subject correlation. The model included the
baseline outcomes (when appropriate), site, and additional minimization variables
(gender, age, LBP severity and duration) as covariates.
Primary outcome measure.
The primary outcomes were group differences in pain
severity at weeks 12, 26, and 52 derived from the linear mixed effect model. Prior to
conducting the analysis, the following strategy was agreed-upon by the statistician to
control for multiple endpoints, but was not described previously in the protocol.  We
used Fisher’s protected least significant difference approach  to control for the
repeated measures. An area under the curve minus baseline summary measure [3, 23]
was used as the omnibus test to determine if the long-term pain profile (including
baseline, 4, 8, 12, 26, and 52 weeks) was different between groups. The omnibus test
needed to be significant (p-value ≤0.05) for group differences at 12, 26, and 52 weeks to
be determined. A site-by-treatment-by-time interaction was included in the linear mixed
effect model if significant (P ≤ 0.05). Clinical and demographic variables were included
as covariates if they were at least moderately correlated with change in outcomes. 
Secondary analyses of the primary outcome measure included group differences at
weeks 4 and 8, the short-term profile (including baseline, 4, 8, and 12 weeks) and the
long-term profile (including all time points). Additionally, responder analyses for no pain
reduction, or pain reductions of 30% (minimal improvement), 50% (moderate
improvement), 75%, and 100% (substantial improvement) were performed at weeks 12,
26, and 52.  Differences in proportions of responders between groups were
calculated and 95% confidence intervals were analyzed using the Wilson method for risk
differences.  Cumulative responder analysis graphs were created to display the
proportion of responders for all possible levels of pain reduction.  Differences in
cumulative response curves were assessed by determining the area under the response
curve using the trapezoidal rule and 95% confidence intervals were calculated using
bias-corrected bootstrapping with 1000 iterations. 
Secondary outcome measures
Secondary outcome measures analyzed for this manuscript included disability,
improvement, medication days, quality of life, patient satisfaction, exercise compliance,
and parent/guardian satisfaction and perceived improvement. Analyses of the secondary
outcome measures included group differences at the relevant individual time points for
all measures, in addition to short-term (including baseline, 4, 8, and 12 weeks) and longterm
(including all time points) profiles for disability, medication days, and improvement.
The same omnibus test approach used for the primary outcome was applied to the
secondary outcomes to control for multiplicity. Non-parametric analyses (i.e.
bootstrapping) were performed as a sensitivity analysis for models with non-normally
distributed residuals.  Results of the objective biomechanical and qualitative data
collection will be reported in separate manuscripts.
Missing Data & Sensitivity Analyses
Linear mixed effect model analyses provide unbiased estimates when data are missing
at random.  The pattern and reasons for missing data were assessed to determine if
sensitivity analyses were necessary for addressing data missing not at random. In
addition, sensitivity analyses were conducted to assess the impact of treatment
compliance and additional healthcare use (e.g. primary care, chiropractic, physical
therapy, massage therapy, surgery) following the 12–week interventions. The impact of
treatment compliance was assessed by a per-protocol analysis of participants who
completed at least 8 intervention sessions. The impact of additional healthcare use after
the end of treatment (12 weeks) was assessed by including an indicator variable for
additional healthcare use as a covariate.
A total of 457 participants were assessed for eligibility, of whom 185 were enrolled, 42 at
the Oregon site and 143 at the Minnesota site (Fig 1). A total of 272 individuals were
excluded from participating; 184 of these were unwilling to participate (reasons given
included no longer interested, time commitment, preference for or against one or both
interventions, and unspecified) and another 88 did not meet the other inclusion criteria.
Allocation resulted in baseline comparability between groups. Table 1 summarizes the
demographic and clinical characteristics of enrolled participants. Over two-thirds (69%)
of participants were female. The duration of back pain was more than 1 year in 72% of
the participants, the mean severity was moderate (5.3), and 11% had radiating pain to
the leg. More than half (54%) reported having treatment for back pain in the past.
Patients in the SMT+ET group had slightly higher expectations of improvement (1–9
scale) from their assigned treatment (mean=2.3, SD=0.7) compared to the ET alone
group (mean=2.5, SD=0.8). Expectation of improvement was very weakly correlated with
change in pain severity (r between –0.13 and –0.18) and was therefore not included as a
covariate when analyzing the primary outcome measure.
Treatment frequency and adherence with the protocol
Overall, 91% of study participants attended their prescribed treatment visits: 96% in the
SMT+ ET group and 87% in the ET alone group. The mean number of ET visits was
10.8 (SD=1.8; median=11.0) in the SMT+ ET group and 9.8 (SD=3.0; median=11.0) in
the ET alone group. The mean number of SMT visits was 10.1 (SD=1.9; median=10) in
the SMT+ ET group. Compliance with home exercise instruction was similar between
groups and declined over time from around 2 days/week at the end of treatment to 1
day/week at one year. During the 12–week intervention, 5 participants reported visits to
other healthcare providers for their LBP: 2 from the SMT+ ET group and 3 from ET
alone. Between weeks 12 and 52, a total of 50 individuals sought additional healthcare:
21 in SMT+ ET (15 sought additional SMT) and 29 in ET alone (18 sought additional
Primary outcome measure.
The longitudinal omnibus test for pain showed SMT+
ET to be significantly superior to ET over the one-year period (P = 0.007). Based on the
adjusted means for reduction in pain severity (0–10 scale), there was an advantage of
0.5 for SMT+ET over ET alone at the end of 12 weeks of treatment (P = 0.083), 1.1 at
week 26 (P = 0.001), and 0.8 at week 52 (P = 0.009)(Table 2 & Figure 2). The SMT+ET
group experienced significantly greater changes in the long-term profile of pain severity
(P = 0.007), but not in the short-term profile (P = 0.55) (Table 2).
Responder analysis of primary outcome.
On average, the difference in
proportions for reduction of LBP severity across all possible thresholds for improvement
favored SMT+ET by approximately 7% at 12 weeks (95% CI –3% to 17%), 17% at 26
weeks (95% CI 8% to 27%), and 10% at 52 weeks (95% CI 0.1% to 20%). Detailed
results from the responder analyses are provided in Table 3 and Figure 3. At 12 weeks,
there were no differences between SMT+ET and ET alone for minimal (≥ 30%) or
moderate (≥ 50%) reductions in LBP severity, but a larger proportion of participants in
the SMT+ET group (10 to 15%) experienced substantial reductions in pain severity (≥
75% or 100%). By week 26, an advantage was noted for SMT+ET across all levels of
reduction in LBP severity, ranging from 14 to 25% greater proportions of participants. At
week 52, approximately 10% more participants from the SMT+ET group reported
minimal or moderate reductions in LBP severity, but these findings were not statistically
significant. Smaller differences were also noted in proportions of patients experiencing a
substantial reduction (≥ 75% or 100%) in LBP severity. In addition, more individuals in
the ET only group reported no reduction or an increase in pain severity at weeks 26 and
Secondary outcome measures.
Longitudinal profiles significantly favored
SMT+ET for disability, improvement, and satisfaction over the long-term (Table 4).
Quality of life and medication use did not significantly differ over the one-year period.
Cross-sectional group differences for disability, improvement, medication use, and
quality of life mainly favored the SMT+ET group, but most differences were not
significant. However, at week 26, SMT+ET was superior to ET in terms of disability and
improvement (Table 4). In addition, the SMT+ET group experienced significantly greater
satisfaction with care than ET alone at weeks 12, 26 and 52. Both groups reported
approximately 80% reduction in medication use at the end of treatment which was
sustained during the entire follow-up period. (Table 4)
Ratings by the parent/guardian showed a significant advantage for the combined group
in the longitudinal profile for satisfaction, but not for improvement (Table 5).
Missing data & sensitivity analyses.
Among the 185 participants, 171 (92%)
provided data on back pain at every time point, and 169 (86%) provided the secondary
outcomes at every time point. A total of 4 participants in the SMT+ET group and 10 in
the ET group did not provide primary outcome data at all time points and the pattern of
missingness appeared to be non-random. We chose to perform two sensitivity analyses
assessing the impact of missing data from these 14 individuals by imputing 1) the 10th
percentile and 2) the 90th percentile by group for the primary outcome at each time
point.  The estimated model coefficients from the sensitivity analyses based on the
imputed data were of similar magnitude and in the same direction as the primary
analysis and all statistically significant between group differences remained the same.
The results from the per-protocol and additional healthcare use sensitivity analyses were
very similar to the primary analysis with slight decreases in group differences, but no
changes in statistical significance or the overall conclusions.
Two serious adverse events (SAEs) occurred during the course of
the trial. Both occurred in the SMT+ET group post intervention and were classified as
unrelated to study interventions. One participant developed appendicitis and had an
appendectomy. Another participant was hospitalized due to renal issues related to type I
diabetes. Minor self-limiting adverse events during the 12 weeks of intervention were
reported with about equal frequency in both group (Table 6). The most commonly
reported adverse events were unusual or increased soreness (51–54%) and different
type of pain (31–34%).
Summary of findings.
To our knowledge, this is the first adequately powered
randomized trial to evaluate the effectiveness of promising non-pharmacologic
interventions for adolescents with chronic LBP. We found that adding SMT to ET
resulted in a larger reduction in the primary outcome of pain severity over the course of
one year. Differences were small and not statistically significant at the end of treatment
(week 12); however, differences were larger and statistically significant at the 6–month
and one-year follow up. Similar results were observed for disability and improvement.
These group differences cannot be explained by contamination in the post treatment
follow-up with approximately the same number of participants in each group seeking
additional healthcare for LBP in the 9 months post-treatment follow-up period. A
sensitivity analysis demonstrated this additional healthcare use had no group differential
impact on the post-treatment follow-up results.
The parent-rated improvement favored the SMT+ET group, and was statistically
significant at week 52. Patient-rated satisfaction with treatment showed a statistically
significant advantage for the SMT+ET group at all time points.
Determination of what constitutes a clinically important group
difference has not been well standardized.  To facilitate interpretation of the outcome
of this trial we considered several factors. This included the magnitude of group
differences, proportion of responders, consistency of outcomes, durability of treatment
effects, intervention safety and tolerability, and participant’s adherence to treatment. 
The magnitude of approximately 11 and 8 percentage points difference between groups
in the primary outcome pain at week 26 and 52 respectively, translates into a moderate
effect size in favor of the SMT+ET group which by most standards is considered
clinically important.  This is supported by responder analysis results where differences
in proportions for reduction of LBP severity across all possible thresholds for reduction in
pain favored SMT+ET by approximately 17% and 10% at weeks 26 and 52, respectively.
Although the differences in patient rated outcomes were small at some time points, they
consistently favored the SMT+ET group after eight weeks of intervention and during the
entire follow-up. Side effects were similar in both groups, mild and self-limiting, and
occurred at a frequency comparable to adult populations. 
Also, given the chronic
nature of LBP in the adolescent participants in this study (mean duration approximately 2
years) it is noteworthy that both groups experienced an approximately 80% reduction in
medication use at the end of treatment, which was further reduced during the one year
follow-up period. These are important findings in light of growing concerns regarding the
safety and effectiveness of pharmacologic treatments for managing pain. Further studies
are needed to assess whether a similar advantage would be observed when compared
to no treatment or pharmacologic control groups. A similarly positive pattern was
observed in parent-rated reports of satisfaction with care, and their perceptions of their
child’s improvement. When considering these factors in aggregate, we interpret the
advantage of SMT+ET over ET alone to be of potential importance and worthy of
additional research. Additionally, the healthcare and societal costs associated with
SMT+ET and ET alone are also necessary to consider when interpreting the clinical
importance of results. These will be addressed in a future manuscript.
Interestingly, in contrast to the ET alone group, the SMT+ET group continued to
experience decreases in LBP severity after the end of treatment resulting in larger longterm
group differences. The continued reduction in LBP severity may be due to the
different, but related underlying mechanisms of action targeted by SMT and ET which
appear to be complementary. The overall course of LBP severity within this sample of
adolescents with chronic LBP receiving ET in combination with SMT was similar to
findings from previous RCTs of adults with similar levels of baseline severity receiving
similar treatment. [6, 46] Analyses of qualitative data collected alongside this trial might
provide additional insights into the psychosocial factors that play a role in adolescents
with LBP who receive these treatments. The qualitative findings will be addressed in a
Comparison to other studies.
Systematic reviews on chronic LBP have found the
most promise for NSAIDs, exercise, and spinal manipulation ; however, there has
been extremely little research performed in younger populations. A recent systematic
review of noninvasive and nonsurgical treatments for LBP in children and adolescents
highlighted the need for more high quality RCTs focused on conservative treatment
strategies to guide clinicians treating children and adolescents with LBP.  Specifically,
the authors found no randomized trials focused on SMT for LBP management; however,
they found three studies [1, 20, 35] focused on exercise that were promising. A metaanalysis
of two studies comparing exercise to no treatment reported an improvement in
pain severity of 2.9 points on a 0–10 scale after 2 to 3 months. 
Since that review, a
large RCT in 8 to 11 year olds concluded that adding regular exercise to education
appears to reduce future episodes of LBP.  In addition, a small RCT in adolescents
with acute LBP of mild intensity found preliminary evidence that the combination of SMT
and exercise did not offer benefits relative to sham SMT and exercise.  Our study of
adolescents with more chronic and moderately severe LBP is a much needed addition to
the evidence base in the important and emerging area of pain management for
adolescent sufferers. With sufficient power and use of standard recommended outcome
measures, our study demonstrated that SMT with exercise provides potentially
worthwhile long-term benefits for adolescents with LBP that is chronic in nature.
Strengths and limitations.
Our trial has several strengths, including adequate
sample size, and a rigorous design intended to be primarily pragmatic but with
substantial emphasis on internal validity. Systematic collection of side effects is also a
strength. Limitations of the study include inability to blind patients and providers to the
nature of the interventions. Further, we are unable to differentiate between specific and
nonspecific treatment effects, such as patient-provider interactions and the differential
time and attention given to the combined SMT+ET group. Qualitative data collected as
part of this trial examining participants’ perspectives are expected to elucidate the impact
of contextual effects associated with the interventions and will be reported in a future
publication. Also, while we were unable to control for placebo and non-specific effects in
this study, there is a strength to comparative effectiveness trials in that by comparing
interventions that approximate how they would be delivered in practice, the findings may
be more readily applicable to clinical practice. 
Compliance with the prescribed
treatment sessions was higher in the SMT+ET group (96%) compared to the ET alone
group (87%). A sensitivity analysis demonstrated that treatment compliance did not
impact the study conclusions. The rate of enrollment (185 enrolled of 457 screened)
was slightly lower than studies performed on adults;  this is a potential limitation in
attempting to generalize study results to non-research settings. Practical considerations
of coordinating both patient and parent schedules likely play a role. However, baseline
LBP severity of our participants is similar to what has been observed in other studies
observing adolescents from a range of settings, [1, 2, 27, 35, 47] which mitigates
generalizability concerns. Finally, this study was not designed to assess the
effectiveness of SMT alone. Our rationale was based on existing evidence supporting
the effectiveness of exercise, the potential for exercise to support patient self-efficacy,
and a previous study we performed that demonstrated exercise and SMT result in similar
outcomes for chronic LBP in adults. 
Implication for clinical practice.
Although adolescents with recurrent, sub-acute
LBP were eligible, only 4% of participants met this criterion. The remaining participants
(96%) had LBP that was chronic in nature. Consequently, the results of this study are
most applicable to adolescents with LBP that is long-standing. Overall a supervised
exercise program with the addition of spinal manipulation appears to be a promising
treatment approach for chronic LBP in adolescents. Given the current limited evidence
base to support management of LBP in adolescents, this has important implications for
providers who use spinal manipulation and exercise in practice such as chiropractors,
physical therapists and osteopaths, and other providers who refer to them.
Implications for future research.
There is still a dire need for more high-quality,
adequately powered research studies to inform the management and the prevention of
LBP in adolescents, especially those that focus on non-pharmacologic interventions.
Future rigorously designed studies are needed to replicate this study, compare SMT and
ET to commonly used medical interventions, and isolate the specific effects from
placebo effects. Further, the cost effectiveness of these approaches requires
investigation to fully inform their promotion for adolescents with LBP.
For adolescents with chronic low back pain, spinal manipulation
combined with exercise therapy was more effective than exercise alone over a one-year
period, with the largest differences occurring at six months. These findings warrant
replication and evaluation of cost-effectiveness.
The authors wish to acknowledge the contributions of our independent statistical
analysis team, dedicated project managers, research clinicians and staff, supporting
institutions (Northwestern Health Sciences University and University of Western States),
as well as funding from the US Department of Health and Human Services
(R18HP15124) and the National Institute of Health's National Center for Complementary
and Integrative Health (K01AT008965 & F32AT007507).
Conflicts of Interest
The authors have no conflict of interests other than the grants listed above.
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