Spine (Phila Pa 1976). 2002 (Nov 1); 27 (21): 2383–2389 ~ FULL TEXT
Roni Evans DC; Gert Bronfort DC; Brian Nelson MD; Charles H Goldsmith PhD
Northwestern Health Sciences University,
Bloomington, Minnesota 55431, USA.
STUDY DESIGN: Randomized clinical trial.
OBJECTIVES: To compare the effects of spinal manipulation combined with low-tech rehabilitative exercise, MedX rehabilitative exercise, or spinal manipulation alone in patient self-reported outcomes over a two-year follow-up period.
SUMMARY OF BACKGROUND DATA: There have been few randomized clinical trials of spinal manipulation and rehabilitative exercise for patients with neck pain, and most have only reported short-term outcomes.
METHODS: One hundred ninety-one patients with chronic neck pain were randomized to 11 weeks of one of the three treatments. Patient self-report questionnaires measuring pain, disability, general health status, improvement, satisfaction, and OTC medication use were collected after 5 and 11 weeks of treatment and 3, 6, 12, and 24 months after treatment. Data were analyzed taking into account all time points using repeated measures analyses.
RESULTS: Ninety-three percent (178) of randomized patients completed the 11-week intervention phase, and 76% (145) provided data at all evaluation time points over the two-year follow-up period. A difference in patient-rated pain with no group-time interaction was observed in favor of the two exercise groups [F(2141) = 3.2; P= 0.04]. There was also a group difference in satisfaction with care [F(2143) = 7.7; P= 0.001], with spinal manipulation combined with low-tech rehabilitative exercise superior to MedX rehabilitative exercise (P = 0.02) and spinal manipulation alone (P < 0.001). No significant group differences were found for neck disability, general health status, improvement, and OTC medication use, although the trend over time was in favor of the two exercise groups.
CONCLUSIONS: The results of this study demonstrate an advantage of spinal manipulation combined with low-tech rehabilitative exercise and MedX rehabilitative exercise versus spinal manipulation alone over two years and are similar in magnitude to those observed after one-year follow-up. These results suggest that treatments including supervised rehabilitative exercise should be considered for chronic neck pain sufferers. Further studies are needed to examine the cost effectiveness of these therapies and how spinal manipulation compares to no treatment or minimal intervention.
From the FULL TEXT Article:
Compared to low back pain, neck pain has been poorly
researched, even though it affects a large number of individuals
and has an important socioeconomic impact.
Surveys in Canada and Finland have found that neck
pain afflicts approximately 70% of adults at some point
in their lives.8,25 Approximately 10% of respondents in a
Canadian study reported having high neck pain levels,
and an additional 5% were severely disabled because of
neck pain.8 Almost 14% of respondents to Norwegian
and Finnish surveys reported having neck pain that was
chronic in nature.2,13
A recent systematic review of the literature of common,
nonsurgical treatments found few randomized clinical
trials on neck pain that were of high methodologic
quality. Furthermore, most reported only short-term
outcomes, with only 2 of 27 having at least a 1-year
We conducted a randomized clinical trial comparing
commonly used treatments for chronic neck pain: 1) spinal
manipulation with low-tech rehabilitative exercise
(SMT/Exercise); 2) high-tech MedX rehabilitative exercise
(MedX); and 3) spinal manipulation (SMT) alone.
The two exercise groups were significantly better than
the SMT group in terms of strength and range of motion
after 11 weeks of treatment and in patient-rated outcomes
one year after treatment. These results have been
presented in a previous publication.3 The current paper
describes the results of the two-year follow-up and addresses
the hypothesis that the advantage observed over
one year in both exercise groups would be sustained two
Materials and Methods
This prospective, parallel-group randomized clinical
trial was conducted at the Wolfe-Harris Center for Clinical
Studies at Northwestern Health Sciences University in Bloomington,
Minnesota, and the Physician’s Neck and Back Clinic in
Roseville, Minnesota. The study was approved by the Institutional
Review Boards of Northwestern Health Sciences University and the University of Minnesota, and informed consent
was obtained from all study participants.
Patients were recruited through newspaper advertisements
in the Minneapolis/St. Paul, Minnesota, area. Initial
screening was done by telephone, and eligible persons attended
two baseline evaluation appointments to fully inform
individuals about the study, establish eligibility, and collect
baseline measures. Qualified and willing individuals were randomly
assigned to one of three treatment groups at the end of
the second baseline evaluation appointment. Randomization
was performed by a member of the study staff using sequentially
numbered, opaque envelopes, which were prepared using
a computer-generated list before the start of the study. The
allocation of the patients to the three study treatments was
1:1:1, and study staff, investigators, clinicians, and patients
were masked to upcoming treatment assignments.
To be eligible for the study, patients had
to be between 20 and 65 years of age and have a primary
complaint of mechanical neck pain that had lasted for 12 weeks
or more. Mechanical neck pain was defined as having no specific,
identifiable etiology (i.e., infection, inflammatory disease),
but could be reproduced by neck movement or provocation
tests.1 Specifically, the pain had to be localized to the
dorsal part of the neck in an area limited by a horizontal line
through the most inferior portion of the occipital region and a
horizontal line through the spinous process of the first thoracic
Exclusion criteria were: neck pain referred from peripheral
joints or viscera, severe osteopenia, progressive neurologic deficits,
vascular disease of the neck or upper extremity, significant
infectious disease or other severe disabling health conditions,
previous cervical spine surgery, current or pending litigation,
inability to work because of neck pain, spinal manipulative
therapy or exercise therapy three months before study entry, or
concurrent treatment for neck pain by other health care
To ensure equal time and attention among the
three treatment groups, all patients attended 20 1-hour appointments
over 11 weeks.
Spinal Manipulation Combined With Rehabilitative Exercise.
Spinal manipulation was delivered by experienced chiropractic
clinicians trained in the study protocol. Treatment included
manual spinal manipulation with light soft-tissue
massage as indicated to facilitate the spinal manipulative therapy.
3 Rehabilitative exercise for the SMT/Exercise group was
guided by trained exercise therapists. Each session began with a
warm-up on a stationary bike with arm levers and light stretching,
followed by upper-body strengthening exercises including
push-ups and dumbbell shoulder exercises.10 Dynamic neck
extension, flexion, and rotation exercises were performed with
the patient lying on a therapy table wearing headgear with
variable weight attachments (1.25 to 10 lbs) guided by a simple
pulley system attached to a physical therapy table. Beginning
weights were determined by baseline strength performance and
were increased gradually during the treatment phase.
MedX Rehabilitative Exercise.
Each appointment began
with a warm-up of stretching and aerobic exercise using a dualaction
stationary bike, followed by strengthening exercises of
the shoulders and upper back using variable resistance equipment.
Neck strengthening exercises were performed on the
MedX variable resistance, cervical extension, and rotation machines
(MedX Corporation, Ocala, FL).23 Patients were stabilized
with torso restraints to isolate and specifically exercise the
cervical musculature. They were encouraged to perform repetitions
to volitional muscle fatigue (maximum 20 reps) even if
pain was exacerbated, and resistance was increased
Patients randomized to the SMT
group received spinal manipulation as described for the SMT/
Exercise group. To minimize differences in potential attention
bias, patients receiving SMT alone were also given 45 minutes
of detuned (sham) microcurrent therapy after the 15 minutes of
evaluation and treatment provided by the chiropractor.
Participants attended evaluation appointments
twice at baseline and 5 and 11 weeks after starting
treatment. Self-report questionnaires were completed, and a
blinded, objective outcomes assessment (including measurement
of neck motion, strength, and endurance) was performed.
At 3, 6, 12, and 24 months after treatment, all participants
were mailed self-report questionnaires to be returned in selfaddressed,
postage-paid envelopes. All outcome measures were
collected independent of provider and investigator influence.
The primary outcome measure was patient-rated pain. Patients
were asked to rate their typical neck pain over the past
week on an ordinal, 11-box scale (0 = no neck pain, 10 = the
worst neck pain possible) — a simple, frequently used assessment
of variation in pain intensity and a reliable measure of
Neck-related disability was measured by the Neck Disability
Index (NDI),32 and general health status was measured by
the Medical Outcomes Study Short Form 36-item Health Survey
Patient-rated improvement or global change was measured
using a nine-point ordinal scale, with response choices ranging
from “no symptoms” to “twice as bad.”9,12,21 Patients were
also asked how frequently they used over-the-counter (OTC),
pain-relieving medication for their neck pain over the past
week using a five-point scale varying from “none” to “everyday.”
4 Satisfaction with care was evaluated on a seven-point
scale which varied from “completely satisfied (couldn’t be better)”
to “completely dissatisfied (couldn’t be worse).”4 Patient
expectations were measured before randomization by asking
patients how they expected to respond to each of the three
possible treatments (worse = 1, no change = 2, better = 3, or
much better = 4). Additional health care use during the follow-
up period was measured by asking patients if they had seen
any nonstudy health care providers for their neck pain since
they filled out their previous self-report questionnaire.
To assess the long-term effects of treatment,
the primary outcome measure, i.e., patient-rated pain, was analyzed
using repeated measures analysis of covariance
(ANCOVA) with data collected at weeks 5 and 11, and months
3, 6, 12, and 24. Baseline values were used as covariates. Possible
treatment-time interactions were accounted for and intention-
to-treat analyses were used.15 Based on variance data from
the ANCOVA table, the preplanned, three-pair–wise comparisons
between groups were performed using the Student-Newman-Keuls multiple range test.11 Patient-rated disability,
general health status, improvement, OTC medication use, and
satisfaction were analyzed in the same way. Data that were not
normally distributed were rank transformed and analyzed using
the same parametric analyses.6 The sample size and statistical
power calculations are described in a previous publication.3
A missing data analysis was performed
to assess to what extent missing data may have affected
the study outcomes using an SPSS Missing Value Analysis™
To assess whether patient expectations and health care use
in the two-year follow-up period had any influence on patientrated
pain, the repeated measuresANCOVAwas repeated with
each variable used as a covariate. These analyses were then
compared to the original analyses.
A repeated measures multivariate analysis of covariance
(MANCOVA) was performed as a confirmatory analysis to
assist with the interpretation of study results. In this analysis,
all patient-rated outcome measures (pain, disability, satisfaction,
improvement, general health status, and OTC medication
use) at all time points were used to test for overall differences
To take into account increasing time intervals between assessments,
areas under the curve were calculated for each patient
for all patient-oriented outcomes as recommended by
Matthews et al.27 Effect size differences were then calculated to
standardize the units of measurement of the outcomes and to
help evaluate the importance of the magnitude of group
Results of Main Analyses
A total of 191 patients were randomized, 178 of which
completed the 11-week treatment period, and 145 provided self-report data for all time points over the
2-year follow-up period. A summary of patient flow
and a detailed account of disqualifiers is reported in a
previous publication.3 Randomization resulted in
three groups comparable on measured clinical and demographic
characteristics3 and are reported in Tables 1 and 2.
The means and standard deviations for all outcomes
at all time points are reported in Table 2. Using repeated
measures ANCOVA, a difference in patient-rated pain
[F(2,141) = 3.2; P = 0.04] with no group-time interaction
was observed in favor of the two exercise groups [SMT/
Exercise vs. SMT (P = 0.05); MedX versus SMT (P = 0.02)] (Figure 1).
Data for improvement, OTC medication use, and satisfaction
were rank transformed. Repeated measures
ANOVA showed a group difference in satisfaction with
care [F(2,143) = 7.7; P = 0.001], with SMT/Exercise superior
to MedX (P = 0.02) and SMT (P = 0.001). No
significant group differences were found for neck disability
[F(2,141) = 2.6; P = 0.08], general health status
[F(2,142) = 2.5; P = 0.08], improvement [F(2,143) = 1.9;
P = 0.15], and OTC medication use [F(2,142) = 1.3; P = 0.27], although the trend over time was in favor of the
two exercise groups.
Twenty-three patients reported increased neck or
headache pain as a result of treatment, with approximately
the same frequency of reporting among the three groups.3
Results of Supplementary Analyses
Controlling for early drop-outs, the pattern of missing
data for all outcomes were determined to be missing
either completely at random (MCAR) or at random
(MAR) within each group, and therefore not related to
measurement history.24 The results of the analysis with
imputed data (using both the expectation-maximization
and regression methods) did not change the results of the
original statistical analysis (data not shown).
The overall MANOVA showed a statistically significant
group difference with no group-time interaction
(Wilk’s Lambda = 0.85)[F(12,272) = 1.9; P = 0.03)], with SMT being inferior to both the SMT/Exercise and MedX exercise groups.
Effect sizes and 95% confidence intervals were calculated
for the area under the curve group differences (Figures 2–4). Near-medium effect size differences (0.3–0.4)
were observed in favor of the two exercise groups in patient-
rated pain, disability, health status, and improvement.
Large effect size differences (0.6–0.8) in favor of SMT/
Exercise were demonstrated for patient-rated satisfaction.
Sixty-nine patients sought additional health care use
after the end of the study treatment phase; 23 in the
SMT/Exercise group, 17 in MedX, and 29 in SMT (χ22 = 3.6; P = 0.165). When the main analysis (repeated measures
ANCOVA for patient-rated pain) was repeated
with additional health care use as a covariate, the results
did not change appreciably [F(2,141)= 3.0; P = 0.06].
The main analysis was also repeated including patient
expectation as a covariate; the results of the sensitivity
analysis were essentially the same as the original analysis
[F(2,141) = 3.0; P = 0.05].
Our study compared the relative long-term effects of spinal
manipulation in combination with low-tech exercise,
high-tech exercise, and spinal manipulation alone for
chronic neck pain. The advantage of SMT/Exercise and
MedX over SMT alone, observed after one year and reported
previously,3 persisted over the two-year follow-
up period. Overall effect size differences varied from
0.3 to 0.4 in favor of the two exercise groups for patientrated
pain, disability, health status, and improvement.
Admittedly, it is questionable whether these differences
are clinically important.17 Based on previous research,
we determined a priori that a medium-effect size difference
(0.5) would be considered clinically relevant. Thus,
for these outcomes, the results fall just short of this cutoff
point. The fact that there are consistent group differences
in most outcome measures across time indicates
the robustness of the results and suggests that although
the differences may be small, they are likely real.
Greater effect size differences of 0.6 to 0.8 were observed
for patient satisfaction, favoring SMT/Exercise
over MedX and SMT. Future studies using qualitative
research methods may be helpful in assessing what “satisfaction
with care” really means to patients and in assisting
with the interpretation of studies similar to ours.
The long-term results of our study suggest an advantage
for the two supervised exercise groups and are consistent
with the findings of a recent randomized clinical
trial by Taimela et al (n = 76).31 They demonstrated that
patients receiving 24 sessions of supervised exercise
faired better than those who exercised at home, experiencing
significantly fewer neck symptoms, greater general
health, and improved working ability at 3 and 12
Two other previous studies evaluating supervised, intensive
exercise have had less promising results.19,30 The
studies by Randlov et al30 and Jordan et al19 had exercise
programs of less frequency and intensity than what was
provided in our study. This may explain the more encouraging
results observed in our trial’s exercise groups
and suggests that dose (how much treatment and at what
intensity) is an important factor in studies assessing supervised
exercise for neck and back pain conditions.19,26
Additional health care use during follow-up periods
can affect outcomes, especially those that are long-term.
After two years, there was no statistically significant difference
between groups in terms of additional health care
use in this study. However, patients in the SMT group
sought the most additional care (29 patients), and those
in the MedX group sought the least (17 patients). Thus,
the effect of additional care in this trial may have resulted
in an overestimate of the treatment effect in the SMT
group, and an underestimate of treatment group differences,
particularly between the SMT and MedX group.
When additional health care use was factored into the
main repeated measures analysis, the significant differences
in patient-rated pain between groups remained.
Patients in this study were recruited through newspaper
advertising, possibly limiting the extent to which the
results can be generalized to clinical settings. However,
there is evidence to suggest that recruitment through advertising
and clinical settings results in patients with similar
demographic and clinical characteristics.9,22 Importantly,
patient demographics in this study were similar to
those in the Jordan et al study,19 in which patients were
recruited mostly through family physician referrals.
In this study, an advantage of SMT/Exercise and MedX
over SMT alone was maintained over the two-year follow-
up period. The SMT/Exercise group was most satisfied
with the care they received. These findings suggest
that treatments including supervised rehabilitative exercise
should be considered for chronic neck pain patients.
Further studies are needed to explore the cost effectiveness
of these treatments and assess how spinal manipulation compares to no treatment or a minimal intervention,
such as a booklet or advice for self-care.
There have been few randomized clinical trials of treatments for neck pain
that have included a two year follow-up.
This randomized clinical trial compared spinal manipulation combined with
exercise, MedX exercise, and spinal manipulation for chronic neck pain over
a two-year period.
The two exercise groups had less pain than the spinal manipulation group,
and patients who received spinal manipulation combined with exercise were
most satisfied with care.
Rehabilitative exercise appears to have positive effects for chronic neck
pain sufferers two years after treatment.
Aust Fam Physician 1984;13:26–30.
Bovim G, Schrader H, Sand T.
Neck pain in the general population.
Bronfort G, Evans R, Nelson B, et al.
A Randomized Clinical Trial of Exercise and
for Patients with Chronic Neck Pain
Spine (Phila Pa 1976). 2001 (Apr 1); 26 (7): 788–797
Bronfort G, Goldsmith CH, Nelson CF, Boline PD, Anderson AV.
Trunk Exercise Combined with Spinal Manipulative or NSAID Therapy
for Chronic Low Back Pain: A Randomized, Observer-blinded Clinical Trial
J Manipulative Physiol Ther. 1996 (Nov); 19 (9): 570–582
Statistical Power Analysis for the Behavioral Sciences.
Hillsdale, NJ: Lawrence Erlbaum Associates; 1988.
Conover WJ, Iman RL.
Rank transformations as a bridge between parametric and nonparametric statistics.
Am Statistician 1981;35:124–33.
Cote P, Cassidy JD, Carroll L.
The factors associated with neck pain and its related disability in the Saskatchewan population.
Cote P, Cassidy JD, Carroll L.
The Saskatchewan health and back pain survey. The prevalence of neck pain and related disability in Saskatchewan adults.
Deyo RA, Walsh NE, Martin DC, et al.
A controlled trial of transcutaneous electrical nerve stimulation (TENS) and exercise for chronic low back pain.
N Engl J Med 1990;322:1627–34.
Dyrssen T, Svedenkrans M, Paasikivi J.
Muskeltraning vid besvar i nacke och skuldror effektiv behandling for att minska smartan.
Lakartidningen 1989; 86:2116–20.
Primer of Biostatistics.
New York, NY: McGraw-Hill; 1992.
Hansen FR, Bendix T, Skov P, et al.
Intensive, dynamic back-muscle exercises, conventional physiotherapy, or placebo-control treatment of low-back
pain. A randomized, observer-blind trial.
Hasvold T, Johnsen R.
Headache and neck or shoulder pain—frequent and disabling complaints in the general population.
Scand J Prim Health Care 1993;11:219–24.
Hedges LV, Olkin I.
Estimation of a single effect size: parametric and nonparametric methods.
In: Statistical Methods for Meta-Analysis. Hedges LV, Olkin I, eds.
Orlando, FL: Academic Press; 1985.
Hulley SB, Cummings SR.
Designing Clinical Research.
Baltimore, MD: Williams & Wilkins; 1988.
Measurement of pain.
Jaeschke R, Singer J, Guyatt GH.
Measurement of health status. Ascertaining the minimal clinically important difference.
Control Clin Trials 1989;10:
Jensen MP, Karoly P, Braver S.
The measurement of clinical pain intensity: a comparison of six methods.
Jordan A, Bendix T, Nielsen H, et al.
Intensive training, physiotherapy, or manipulation for patients with chronic neck pain. A prospective, singleblinded, randomized clinical trial.
Kjellman GV, Skargren EI, Oberg BE.
A critical analysis of randomised clinical trials on neck pain and treatment efficacy. A review of the literature.
Scand J Rehabil Med 1999;31:139–52.
Koes BW, Bouter LM, van Mameren H, et al.
A blinded randomized clinical trial of manual therapy and physiotherapy for chronic back and neck complaints: physical outcome measures.
J Manipulative Physiol Ther 1992;15: 16–23.
Koes BW, Bouter LM, van Mameren H, et al.
The effectiveness of manual therapy, physiotherapy, and treatment by the general practitioner for nonspecific
back and neck complaints. A randomized clinical trial.
Spine 1992; 17:28–35.
Leggett SH, Graves JE, Pollock ML, et al.
Quantitative assessment and training of isometric cervical extension strength.
Am J Sports Med 1991;19: 653–9.
Little RJA, Rubin D.
Statistical Analysis With Missing Data.
New York, NY: J. Wiley & Sons; 1987.
Makela M, Heliovaara M, Sievers K, et al.
Prevalence, determinants, and consequences of chronic neck pain in Finland.
Am J Epidemiol 1991;134: 1356–67.
Manniche C, Jordan A.
The value of exercise therapy (editorial).
Spine 1995; 20:1221–22.
Matthews JN, Altman DG, Campbell MJ, et al.
Analysis of serial measurements in medical research.
McHorney CA, Ware JE, Raczek AE.
The MOS 36-item short-form health survey (SF-36). II: Psychometric and clinical tests of validity in measuring
physical and mental health constructs.
Med Care 1993;31:247–63.
Nelson BW, Carpenter DM, Dreisinger TE, et al.
Can spinal surgery be prevented by aggressive strengthening exercises? A prospective study of cervical and lumbar patients.
Arch Phys Med Rehabil 1999;80:20–25.
Randlov A, Ostergaard M, Manniche C, et al.
Intensive dynamic training for females with chronic neck/shoulder pain. A randomized controlled trial.
Clin Rehabil 1998;12:200–10.
Taimela S, Takala EP, Asklof T, et al.
Active treatment of chronic neck pain: a prospective randomized intervention.
Vernon H, Mior S.
The Neck Disability Index: A Study of Reliability and Validity
J Manipulative Physiol Ther 1991 (Sep); 14 (7): 409–415
Ware JE, Sherbourne CD.
The MOS 36-item short-form health survey (SF-36).
Med Care 1992;30:473–81.
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