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SPINE Volume 27, Number 24, pp 2835–2843
©2002, Lippincott Williams & Wilkins, Inc.
A Clinical Prediction Rule for Classifying Patients with
Low Back Pain Who Demonstrate Short-Term
Improvement With Spinal Manipulation
Timothy Flynn, PT, PhD,*‡ Julie Fritz, PT, PhD,† Julie Whitman, PT, DSc,‡
Robert Wainner, PT, PhD,*‡ Jake Magel, PT, DSc,‡ Daniel Rendeiro, PT, DSc,‡
Barbara Butler, PT,‡ Matthew Garber, PT, DSc,‡ and Stephen Allison, PT, PhD*
Study Design. A prospective, cohort study of patients
with nonradicular low back pain referred to physical
therapy.
Objective. Develop a clinical prediction rule for identi-
fying patients with low back pain who improve with spi-
nal manipulation.
Summary of Background Data. Development of clini-
cal prediction rules for classifying patients with low back
pain who are likely to respond to a particular intervention,
such as manipulation, would improve clinical decision-
making and research.
Methods. Patients with nonradicular low back pain
underwent a standardized examination and then under-
went a standardized spinal manipulation treatment pro-
gram. Success with treatment was determined using per-
cent change in disability scores over three sessions and
served as the reference standard for determining the ac-
curacy of examination variables. Examination variables
were first analyzed for univariate accuracy in predicting
success and then combined into a multivariate clinical
prediction rule.
Results. Seventy-one patients participated. Thirty-two
had success with the manipulation intervention. A clinical
prediction rule with five variables (symptom duration,
fear–avoidance beliefs, lumbar hypomobility, hip internal
rotation range of motion, and no symptoms distal to the
knee) was identified. The presence of four of five of these
variables (positive likelihood ratio !24.38) increased the
probability of success with manipulation from 45% to 95%.
Conclusion. It appears that patients with low back pain
likely to respond to manipulation can be accurately iden-
tified before treatment. [Key words: manipulation, classi-
fication, low back pain, likelihood ratio, clinical prediction
rule] Spine 2002;27:2835–2843
Attempts to identify effective interventions for patients
with low back pain (LBP) have been largely unsuccess-
ful.
65,66
One explanation offered for the lack of evidence
is the inability to define subgroups of patients most likely
to respond to a particular intervention.
8,39
Without the
ability to match patients to specific interventions, clini-
cians are left without evidence or guidance for their de-
cision-making. Because of the difficulty in subgrouping
patients with LBP based on pathoanatomy,
67
attempts
have been made to classify patients based on findings
from the history and physical examination.
17,49,60,64
De-
veloping effective, clinically applicable methods for clas-
sifying patients with LBP could improve decision-
making and outcomes by matching interventions to the
patients they are most likely to benefit. Classification
methods would also enhance the power of clinical re-
search by permitting researchers to study more homoge-
neous groups of patients.
56
Identifying methods for clas-
sifying patients with LBP has been identified as an
important research priority.
1,6,66
Manipulation is an intervention commonly used in
the treatment of individuals with LBP. Several random-
ized trials have found manipulation to be more effective
than placebo
52,54,71
or other interventions.
16,22,36,63
However, other studies have not shown any benefits for
manipulation versus other interventions.
10,26–28
The dis-
parity may be partly attributable to the admission of a
heterogeneous group of patients with LBP without an
attempt to identify a priori those likely to benefit from
the intervention. Other randomized trials have found
manipulation to be more beneficial for a subgroup of
patients with more acute symptoms
30,42
or more limited
straight-leg raise range of motion.
47
No previous studies
have sought to develop a multifactorial classification rule
that would maximize the prediction of success with ma-
nipulation before the intervention.
One subgroup of patients for whom manipulation is
proposed to be effective comprises individuals with sac-
roiliac (SI) region dysfunction.
16,19,22,29,62,71
Numerous
clinical findings have been promoted as capable of iden-
tifying patients with SI dysfunction; however, previous
studies have questioned the reliability and validity of
many of these tests.
4,9,20,21,37,40,41,44,45,50,53,61
Previous
studies have generally examined individual tests for SI
dysfunction in isolation and typically have not included
other potentially important factors from the history or
From the *U.S. Army-Baylor University Graduate Program in Physical
Therapy, San Antonio, Texas, the †Department of Physical Therapy,
University of Pittsburgh, Pittsburgh, Pennsylvania, and the ‡U.S. Army-
Baylor University, Postprofessional Doctoral Program in Orthopaedic
& Manual Physical Therapy, Fort Sam Houston, Texas.
Supported in part by a grant from the Foundation for Physical
Therapy.
Acknowledgment date: October 31, 2001. First revision date: March 7,
2002. Acceptance date: May 6, 2002.
The manuscript submitted does not contain information about medical
device(s)/drug(s).
Foundation funds were received in support of this work. No benefits in
any form have been or will be received from a commercial party related
directly or indirectly to the subject of this manuscript.
The opinions and assertions contained herein are the private views of
the author and are not to be construed as official or as reflecting the
views of the Department of the Army or the Department of Defense.
Address correspondence to Timothy W. Flynn, PT, PhD, U.S. Army-
Baylor University Graduate Program in Physical Therapy, 3151 Scott
Road, Room 1303, Fort Sam Houston, TX 78234-6138, USA; E-mail:
timothy.flynn@cen.amedd.army.mil
2835
examination. An exception is the work published by Cib-
ulka et al, who described a cluster of movement and
provocative tests purported to identify SI joint dysfunc-
tion.
12–14
However, this test cluster was chosen based on
the authors’clinical experience, and the predictive valid-
ity is unknown.
12
Furthermore, most studies have used
short-term pain relief with an injection of an anesthetic
agent into the SI joint as the reference standard against
which validity has been judged.
9,21,32,44
The validity of
using anesthetic joint blocks as a reference standard for
diagnostic studies has not been demonstrated.
3,32,59
The
reference standard should represent the condition of in-
terest that the diagnostic test is attempting to identify.
55
If the goal of a test is to identify patients likely to respond
to an intervention directed toward the SI region (e.g.,
manipulation), then the use of a criterion standard of
short-term pain relief with an injection is questionable. A
more viable alternative may be a longer duration re-
sponse to the intervention in question. A study using a
more “therapeutic”reference standard, which considers
a broader variety of clinical findings and attempts to
combine clinical findings, will be more useful in identi-
fying a subgroup of patients with SI dysfunction who are
likely to respond to spinal manipulation. The purpose of
this study was to develop a clinical prediction rule for
identifying patients with LBP likely to respond favorably
to a specific manipulation technique. A variety of find-
ings were considered against a reference standard of
change in disability.
Methods
A prospective cohort study of patients with LBP was conducted
at two outpatient facilities: Brooke Army Medical Center and
Wilford Hall Air Force Medical Center. Patients were between
the ages of 18 and 60 years, referred to physical therapy with a
diagnosis related to the lumbosacral spine, and had a chief
complaint of pain and/or numbness in the lumbar spine, but-
tock, and/or lower extremity. The baseline Oswestry disability
score had to be at least 30%. Exclusion criteria were current preg-
nancy, signs consistent with nerve root compression (positive
straight-leg raise at "45°,ordiminishedlowerextremitystrength,
sensation, or reflexes), prior lumbar spine surgery, or a history of
osteoporosis or spinal fracture. All patients were briefed on the
purpose of the study and signed an informed consent approved by
the Brooke Army Medical Center and Wilford Hall Air Force
Medical Center Institutional Review Boards.
Therapists. Eight licensed physical therapists participated.
Four were residents in the U.S. Army-Baylor Post-Professional
Doctoral Program in Orthopedic and Manual Physical Ther-
apy, and four were instructors in the program. This program is
designed to provide physical therapists serving in the U.S. Mil-
itary with advanced training in orthopedic and manual physi-
cal therapy. A 1-day training session was conducted for partic-
ipating therapists to standardize examination and treatment
techniques.
Examination Procedures. Patients completed a baseline ex-
amination including demographic information and a pain rat-
ing using an 11-point scale.
34
A pain diagram
46
was used to
categorize symptoms as low back, buttock/thigh, or distal to
the knee based on the distal-most extent of symptoms.
70
The
Modified Oswestry Disability Questionnaire (OSW) assessed
disability related to LBP.
25
The Fear-Avoidance Beliefs Ques-
tionnaire (FABQ) was used to assess the patient’s beliefs about
the influence of activity on LBP.
69
The FABQ contains two
subscales: one is related to general physical activity and the
other to work.
69
Patients underwent a standardized history and physical ex-
amination. History included mechanism of injury, nature of
current symptoms, and prior episodes of LBP. Patients were
asked to rank sitting, standing, and walking as to which was
best and worst with respect to symptoms. The examination
included Waddell’s nonorganic signs.
68
Range of motion and
status change
49
in symptoms with single lumbar movements
were recorded. Supine straight-leg raise and prone hip rotation
range of motion were measured. Posteroanterior spring test-
ing
43
was performed for pain provocation and mobility at each
lumbar level. Mobility was judged as normal, hypomobile, or
hypermobile. Numerous special tests proposed to be diagnostic
of SI dysfunction were performed (see Appendix). The tests
were divided into three categories: position (tests assessing
symmetry of bony landmarks), provocation (tests to reproduce
symptoms), and mobility (tests assessing symmetry of pelvic
motion).
37
The examination was repeated on the first 55 sub-
jects by a second therapist blinded to the results of the first
examiner to determine the reliability of the physical examina-
tion variables.
Treatment. Because response to treatment served as the refer-
ence standard, all patients were treated with the same protocol
for two sessions. At the first session, the therapist performed a
manipulation technique with the patient supine. The therapist
stood opposite the side to be manipulated. The patient was
passively side-bent away from the therapist. The therapist pas-
sively rotated the patient and then delivered a quick posterior
and inferior thrust through the anterior superior iliac spine
(Figure 1). The side to be manipulated was determined with the
following algorithm: first, the side of the positive standing flex-
ion test; if this test was negative, the side of tenderness during
sacral sulcus palpation was manipulated. If neither side was
tender, the side reported by the patient to be more symptomatic
was manipulated. If the patient was unable to identify a more
Figure 1. Manipulation technique used in this study.
2836 Spine •Volume 27 •Number 24 •2002
symptomatic side, the therapist flipped a coin to determine the
side. Although the manipulation was performed on one side
only, Cibulka et al
12
found changes in innominate tilt on both
sides of the pelvis after applying this technique. Therefore,
whereas the algorithm provided a consistent approach, it is
likely the manipulation affected bilateral SI regions.
After the manipulation, the therapist noted whether a cavi-
tation was heard or felt by the therapist or patient. If a cavita-
tion was experienced, the therapist proceeded to the other
treatment components. If no cavitation was produced, the pa-
tient was repositioned, and the manipulation was attempted
again. If no cavitation was experienced again, the therapist
attempted to manipulate the opposite side. A maximum of two
attempts per side was permitted. If no cavitation was produced
after the fourth attempt, the therapist proceeded to the other
treatment components. Two additional treatment components
were included: 1) instruction in a supine pelvic tilt range of
motion exercise (the patient was instructed to perform 10 rep-
etitions, 3–4 times daily; and 2) instruction to maintain usual
activity level within the limits of pain.
5
The second treatment session occurred 2–4 days after the
first. Before the second session, each patient completed an
OSW questionnaire. Percentage improvement in OSW was cal-
culated (initial score #final score)/initial score $100). If im-
provement was %50%, the patient was categorized as a suc-
cess, and study participation ended. If the patient showed
"50% improvement, the therapist repeated the examination
and the manipulation procedures. The third session occurred
2–4 days after the second. The patient again completed the
OSW, and the percentage improvement from the initial score
was calculated. If %50% improvement was noted, the patient
was categorized as a success. If improvement was !50%, the
patient was categorized as a nonsuccess. At this point, the pa-
tient’s study participation ended, and further treatment was
administered as needed.
Data Analysis. Kappa coefficients were calculated to deter-
mine the interrater reliability of the special tests for SI dysfunc-
tion. Patients were dichotomized based on success or nonsuc-
cess with respect to the treatment. Success or nonsuccess was
then used as the reference standard. Individual variables from
the self-reports, history, and physical examination were tested
for their univariate association with the reference standard us-
ing independent sample ttests for continuous variables and
"
2
tests for categorical variables. Variables with a significance
level of P"0.15 were retained as potential prediction vari-
ables; a more liberal significance level was chosen at this stage
to avoid excluding potential predictive variables. For continu-
ous variables with a significant univariate association, sensitiv-
ity and specificity values were calculated for all possible cut-off
points and then plotted as a receiver operator characteristic
(ROC) curve.
31
The point on the curve nearest the upper left-
hand corner represents the value with the best diagnostic accu-
racy, and this point was selected as the cut-off defining a posi-
tive test.
18
Sensitivity, specificity, and positive likelihood ratios
(PLR) were calculated for all potential prediction variables.
57
The PLR is calculated as sensitivity/(1 #specificity) and indi-
cates the increase in the probability of success given a positive
test result.
58
A PLR of 1 indicates the test does nothing to alter
the probability of success, whereas PLR values %1 increase the
probability of success given a positive test result. According to
Jaeschke et al,
33
PLR values between 2.0 and 5.0 generate small
shifts in probability, values between 5.0 and 10.0 generate
moderate shifts, and values %10.0 generate large and often
conclusive shifts in probability. We chose to focus on the PLR
as opposed to the negative LR because we were attempting to
predict success with manipulation based on positive test re-
sults. Potential prediction variables were entered into a step-
wise logistic regression equation to determine the most parsi-
monious set of predictors for success using a multivariate
model. A significance of 0.05 was required to enter a variable
into the model and a significance of 0.10 was required to re-
move it. Variables retained in the regression model were used to
develop a multivariate clinical prediction rule for classifying
patients as likely responders to manipulation.
Results
Seventy-five patients entered the study. Four subjects
(5%) did not return after the first session and were not
included in the analysis. Two subjects left the study be-
cause of personal or work-related circumstances. One
subject dropped out because of complications from an
ongoing episode of gastrointestinal distress, and one sub-
ject failed to return for his final visit. Of the 71 patients
completing the study, 29 (41%) were female and 59
(83%) had a prior history of LBP. The mean age was
37.6 &10.6 years (range 18–59 years). The mean OSW
score at baseline was 42.4 &11.7, and at study conclu-
sion 25.1 &13.9. The mean percent improvement in
OSW over the study period was 41.0 &33.9% (range
#29.0–100%). Thirty-two patients (45%) were classi-
fied as treatment successes, and 39 (55%) were nonsuc-
cesses. Twenty patients were successes after one manipula-
tion session, 12 after two sessions. The mean improvement
in OSW in the success group over the study period was 32.5
&12.6 points, with a mean percent improvement of 73.2 &
15.8%. In the nonsuccess group, the mean OSW improve-
ment was 6.2 &7.8 points, with a mean percent improve-
ment of 14.6 &18.2% (Figure 2).
Among self-reported variables (Table 1), the FABQ
work subscale, the presence of symptoms in the back
Figure 2. Initial and final Oswestry scores for the success and
nonsuccess groups. The mean percent change in the success
group was 73.2 &15.8%. For the nonsuccess group, the mean
percent change was 14.6 &18.2%.
2837Clinical Prediction Rule for Spinal Manipulation •Flynn et al
only, and symptoms distal to the knee were retained as
potential prediction variables. From the history (Table
2), duration of symptoms, increasing episode frequency,
and ranking standing as the worst position were re-
tained. Five variables were retained from the clinical ex-
amination (Table 3): left and right hip internal rotation,
hypomobility and pain with lumbar spring testing, and
peripheralization with single lumbar movement testing.
The special tests for SI dysfunction along with the reli-
ability coefficients are presented in Table 4. As a group,
the provocation tests were more reliable with values
ranging from fair to substantial agreement. The Gillet
test was the only motion test to demonstrate at least
moderate agreement. The anterior superior iliac spine
and iliac crest in standing and the posterior superior iliac
spine symmetry in sitting were the only symmetry tests to
have at least fair agreement. Among the special tests for
SI dysfunction (Table 4), only the compression–
distraction test was retained in the predictive model, al-
though positive findings were more common in the non-
success group. Cut-off values for retained continuous
variables (duration of symptoms, FABQ work subscale,
left and right hip internal rotation) were obtained from
receiver operator characteristic curve analyses. Because
of their similarity, left and right hip internal rotations
were combined into a single variable. Cut-off scores and
accuracy statistics for retained variables were calculated
(Table 5). Among historical variables, duration of symp-
toms "16 days was most predictive of success (PLR !
4.39).
The 11 potential prediction variables were entered
into the logistic regression. Five were retained in the final
model: duration of symptoms "16 days, at least one hip
with %35°of internal rotation, hypomobility with lum-
bar spring testing, FABQ work subscale score "19, and
no symptoms distal to the knee (model
"
2
!48.5, df !5,
P"0.001, Nagelkerke R
2
!0.67). These five variables
were used to form the clinical prediction rule. Only six
subjects (all in the success group) were positive for all five
retained prediction variables at baseline (Table 6). Four-
teen of 15 subjects with 4 of 5 variables present were in
the success group. Of subjects with two or fewer vari-
ables present, 25 of 27 were in the nonsuccess group.
Accuracy statistics were calculated for each level of the
clinical prediction rule (Table 7). Based on the pretest
probability of success with manipulation found in this
study (45%), and the PLR values calculated, a subject
with four or more variables present at baseline increases
Table 1. Self-Report Variables Used in the Study
Self-Report Variable All Subjects (n !71)
Manipulation Success
(n !32)
Manipulation
Nonsuccess (n !39) Significance
Pain rating 5.3 (2.0) 5.3 (2.0) 5.2 (1.7) 0.74
Oswestry score 42.4 (11.7) 44.4 (14.4) 40.8 (8.7) 0.21
Fear avoidance beliefs
Work subscale 12.9 (10.3) 9.1 (8.3) 16.0 (10.8) 0.003
Physical activity subscale 15.1 (5.3) 14.9 (5.0) 15.2 (5.6) 0.85
Pain diagram (%)
Low back symptoms only 31 41 23 0.11
Buttock/thigh symptoms present 76 69 82 0.19
Symptoms distal to knee 25 13 36 0.024
Values are means (SD) unless otherwise indicated.
Table 2. Variables From the Patient History Used in This Study
Variable All Subjects
Manipulation
Success
Manipulation
Nonsuccess Significance
Age (yrs) 37.6 (10.6) 39.5 (11.7) 36.1 (9.1) 0.19
Gender (% female) 41 47 36 0.35
Duration of symptoms (days) 41.7 (54.7) 23.5 (32.5) 56.7 (64.4) 0.007
Mode of onset (%)
Gradual 31 26 33 0.64
Sudden (minimal/no perturbation) 39 48 33 0.24
Traumatic (fall, lifting, pulling, etc.) 30 26 33 0.44
Prior history of low back pain (%) 83 88 79 0.37
Episodes of low back pain becoming more frequent (%) 35 25 44 0.10
Sitting ranked as best position (%) 31 31 31 0.97
Standing ranked as best position (%) 20 25 15 0.31
Walking ranked as best position (%) 23 16 28 0.21
Sitting ranked as worst position (%) 41 47 36 0.35
Standing ranked as worst position (%) 27 19 36 0.055
Walking ranked as worst position (%) 13 16 10 0.50
Values are means (SD) unless otherwise indicated.
2838 Spine •Volume 27 •Number 24 •2002
his or her probability of success with manipulation from
45% to 95%. If the criteria were changed to three or
more variables present, the probability of success was
only increased to 68%. If two or fewer variables were
present, the probability of success was virtually
unchanged.
Discussion
Clinicians who routinely use spinal manipulation have
encountered patients who experience a rapid, even dra-
matic improvement as a result of one or two treatments,
whereas others change very little. The ability to accu-
Table 3. Variables From the Baseline Clinical Examination Used in This Study
Variable All Subjects
Manipulation
Success
Manipulation
Nonsuccess Significance
Nonorganic signs* 0.70 (1.0) 0.48 (0.77) 0.74 (1.1) 0.25
Total flexion (°) 75.7 (30.0) 75.3 (31.2) 81.1 (25.7) 0.40
Pelvic flexion (°) 38.0 (20.7) 37.4 (19.9) 41.1 (20.5) 0.45
Lumbar flexion (°) 38.3 (15.4) 37.6 (18.4) 40.0 (12.5) 0.58
Total extension (°) 21.5 (9.5) 21.4 (8.2) 21.4 (9.8) 0.98
Left side bending (°) 27.5 (7.8) 27.6 (7.7) 28.1 (8.0) 0.80
Right side bending (°) 27.3 (7.2) 27.0 (6.4) 28.1 (7.5) 0.53
Left and right side bending discrepancy†(°) 5.2 (4.7) 6.0 (4.4) 4.7 (5.0) 0.26
Left straight leg raise (°) 67.3 (16.8) 69.2 (14.9) 68.5 (16.3) 0.85
Right straight leg raise (°) 67.5 (16.7) 68.6 (14.3) 69.2 (16.7) 0.87
Left and right straight-leg raise discrepancy†(°) 6.0 (6.9) 5.6 (5.6) 6.5 (8.1) 0.59
Left hip internal rotation (°) 29.6 (9.8) 33.0 (9.7) 27.2 (9.3) 0.012
Right hip internal rotation (°) 30.3 (12.5) 29.6 (10.4) 25.9 (10.7) 0.15
Left and right hip internal rotation discrepancy†(°) 6.4 (5.7) 6.8 (6.5) 6.0 (5.3) 0.58
Left hip external rotation (°) 30.1 (11.9) 31.3 (13.3) 29.5 (12.9) 0.48
Right hip external rotation (°) 30.3 (12.5) 31.8 (12.6) 29.3 (11.1) 0.45
Left and right hip external rotation discrepancy†(°) 6.1 (5.3) 5.8 (5.3) 6.6 (5.4) 0.53
Hypomobility at one or more lumbar levels with spring testing (%) 86 97 77 0.016
Pain at one or more lumbar levels with spring testing (%) 92 97 87 0.14
Lateral shift present (%) 13 13 13 0.97
Peripheralizes with lumbar single movement testing (%) 25 16 33 0.088
Centralizes with lumbar single movement testing (%) 6 6 5 0.84
Values represent means (standard deviation) unless otherwise indicated.
* Mann-Whitney test used due to non-normal data distribution.
† Discrepancy values were calculated as the absolute value of the left minus the right.
Table 4. Special Tests for SI Dysfunction Used in This Study
Reliability All Subjects (%)
Manipulation
Success (%)
Manipulation
Nonsuccess (%) Significance
Provocation tests
Posterior shear test 0.70 56 56 56 0.99
Sacral sulcus test 0.64 67 75 62 0.23
Patrick test 0.60 44 47 41 0.62
Gaenslen test 0.54 44 47 44 0.78
Resisted hip abduction 0.41 36 34 38 0.72
Sacral thrust test 0.41 54 63 49 0.25
Compression–distraction test 0.26 23 16 31 0.14
Motion tests
Gillet test 0.59 60 66 56 0.43
Seated flexion test 0.25 66 72 59 0.26
Long-sitting test 0.21 46 39 51 0.35
Prone knee bend test 0.21 56 47 62 0.22
Standing flexion test #0.08 54 47 62 0.22
Symmetry tests
ASIS symmetry in standing 0.31 36 41 33 0.53
Iliac crest symmetry in standing 0.23 33 34 33 0.93
PSIS symmetry in sitting 0.23 31 31 31 0.97
PSIS symmetry in standing 0.13 41 44 38 0.65
Ischial tuberosity heights in prone 0.03 41 35 46 0.43
Pubic tubercle symmetry in supine #0.04 49 41 56 0.18
ASIS !anterior superior iliac spine; PSIS !posterior superior iliac spine.
Reliability measured with kappa and weighted kappa statistics. Percentage values represent the percentage of positive tests in all patients and the success and
nonsuccess groups.
2839Clinical Prediction Rule for Spinal Manipulation •Flynn et al
rately predict which patients will have which response a
priori would be immensely beneficial for clinical deci-
sion-making. Similar to other studies,
21,40,41,44
we were
unable to show acceptable accuracy for any individual
tests proposed to identify SI dysfunction. Furthermore,
we found that the reliability of these tests in a population
of individuals with LBP is less than optimal. As noted by
previous researchers, provocation tests as a whole are
more reliable tests than motion or symmetry tests.
9,37
However, by considering other variables and combining
findings, we were able to develop a clinical prediction
rule that may be useful for assisting clinicians in classi-
fying patients as likely to respond to this manipulation
technique.
The developed clinical prediction rule contains five
variables: duration of symptoms "16 days, at least one
hip with %35°of internal rotation, lumbar hypomobil-
ity, no symptoms distal to the knee, and an FABQ work
score "19. These findings are generally consistent with
previous theories and research. Randomized trials have
suggested that patients with more acute symptoms re-
spond better to manipulation.
30,42
Our results support
this hypothesis. Hip rotation range of motion discrepan-
cies have been reported in patients with LBP.
2,14,51
Pre-
vious studies in patients with “nonspecific”LBP have
found greater external rotation than internal rota-
tion.
2,11,51
As a whole, patients in this study had greater
external than internal rotation; however, increased inter-
nal rotation was associated with manipulation success.
Manipulation is thought to be indicated in the presence
of hypomobility. Interestingly, although the technique
used in this study is described as affecting the SI region, it
was lumbar hypomobility that entered the prediction
model. This finding reinforces the idea that the manipu-
lation technique is not specific to the SI region but im-
pacts the lumbar spine as well.
7,17,29
Manipulation is
generally thought to be contraindicated in patients with
radiculopathy.
5
We excluded patients with signs of nerve
root compression. However, some patients with symp-
toms distal to the knee were included, and these patients
tended not to succeed. Finally, the FABQ quantifies a
patient’s fear of pain and subsequent avoidance of activ-
ity.
69
The FABQ work subscale has been previously cor-
related with work loss and disability in patients with
chronic and acute LBP.
24,35,69
Our results suggest that
patients with high levels of fear-avoidance beliefs about
work activities are unlikely to respond to manipulation.
These individuals likely require an alternative treatment
approach.
15
The usefulness of a clinical prediction rule for classi-
fying patients is best expressed using likelihood ratio
statistics. The PLR expresses the change in odds favoring
the outcome when the patient meets the prediction rule’s
criteria.
57
In our sample, 45% of subjects were successful
without any attempt at prediction. In other words, ran-
domly manipulating individuals with nonradicular LBP
may result in success about 45% of the time. Using a
criterion of at least 4 of 5 variables present at baseline
(PLR !24.38), the probability of success is raised to
95%; therefore, these individuals should be manipu-
lated. If only three variables are present, the probability
increased to 68%, which is likely sufficient to warrant an
attempt at manipulation in these patients. When two or
fewer variables are present, the probability of success
changes little, and clinicians should consider alternative
treatments if such can be identified that may have a prob-
ability of success %45%.
An important consideration in the examination of di-
agnostic tests is the reference standard against which
tests are judged. Previous studies of tests for SI dysfunc-
tion have generally used immediate pain relief with SI
Table 6. Number of Subjects in the Success and
Nonsuccess Groups at Each Level of the Clinical
Prediction Rule
No. of Predictor
Variables
Present
No. of Subjects in
the Manipulation
Success Group
No. of Subjects in
the Manipulation
Nonsuccess Group
560
4 14 1
3 10 13
2 2 19
105
001
Table 5. Accuracy Statistics (With 95% Confidence Intervals) for Individual Variables for Predicting Success
Variable Associated With Success Sensitivity Specificity Positive Likelihood Ratio
Duration of symptoms !15 days 0.56 (0.39, 0.72) 0.87 (0.73, 0.94) 4.39 (1.83, 10.51)
Episodes not becoming more frequent 0.75 (0.58, 0.87) 0.44 (0.29, 0.59) 1.33 (0.95, 1.87)
Standing not ranked as worst position 0.84 (0.67, 0.93) 0.36 (0.23, 0.52) 1.31 (1.0, 1.74)
FABQ work subscale !18 0.84 (0.68, 0.93) 0.49 (0.34, 0.64) 1.65 (1.17, 2.31)
Symptoms in the low back only 0.41 (0.26, 0.58) 0.77 (0.62, 0.87) 1.76 (0.87, 3.58)
Symptoms not distal to the knee 0.88 (0.72, 0.95) 0.36 (0.23, 0.52) 1.36 (1.04, 1.79)
At least one hip internal rotation range of motion %35°0.50 (0.34, 0.66) 0.85 (0.70, 0.93) 3.25 (1.44, 7.33)
Hypomobility at one or more lumbar levels with spring testing 0.97 (0.84, 0.99) 0.23 (0.13, 0.38) 1.26 (1.05, 1.51)
Pain at one or more lumbar levels with spring testing 0.97 (0.84, 0.99) 0.13 (0.056, 0.27) 1.11 (0.97, 1.27)
Does not peripheralize with lumbar single movement testing 0.84 (0.68, 0.93) 0.33 (0.21, 0.49) 1.27 (0.97, 1.65)
Negative compression/distraction test 0.84 (0.68, 0.93) 0.31 (0.19, 0.46) 1.22 (0.94, 1.58)
FABQ !Fear-Avoidance Beliefs Questionnaire.
2840 Spine •Volume 27 •Number 24 •2002
joint anesthetic injection. In our opinion, clinicians per-
forming these tests are not as interested in pathoana-
tomic speculations (i.e., is the SI joint generating the
pain?) as they are in determining if the patient will re-
spond to a particular intervention. We therefore used a
reference standard representative of the desired outcome
of the tests (i.e., responding to manipulation). The use of
50% improvement on the OSW as the reference standard
was based on previous research involving the interven-
tion used in this study. In three previous studies, patients
thought to be matched to this intervention experienced
mean improvements in OSW scores from 57% to 83%,
whereas patients receiving unmatched interventions ex-
perienced mean improvements ranging from 20% to
38% over a 1–4-week period.
16,22,23
We therefore
thought that requiring 50% improvement in the OSW
over a 2–4-day period would provide adequate distinc-
tion between patients responding to the intervention and
those simply benefiting from the favorable natural his-
tory of LBP.
The patients participating in this study should be rep-
resentative of patients seeking physical therapy services
in large metropolitan areas. The eight physical therapists
involved in the study had varying degrees of skills in
spinal manipulative therapy. However, the manipulation
technique employed is a standard technique used in
physical therapist education programs. Therefore, the
results should be generalizable to outpatient clinics treat-
ing individuals with LBP.
A three-step process for developing and testing a clin-
ical prediction rule is recommended.
48
The first step is
developing the rule, the second step is validation, and the
third step is an assessment of the impact of the rule on
clinical behavior. The purpose of the present study was
to develop a clinical prediction rule that would identify
individuals with LBP who respond favorably to a specific
spinal manipulation. In the present study, only one ma-
nipulation technique was used, and it is unknown
whether other techniques would provide similar results.
Validation of the proposed clinical prediction rule is the
purpose of an ongoing randomized controlled trial where
subjects meeting the prediction criteria receive either the
spinal manipulation technique or a competing therapy. Ul-
timately, any clinical prediction rule must be shown to im-
prove outcomes and clinical decision-making before it can
be advocated for widespread use.
38,48
Key Points
●Special tests purported to identify patients with
low back pain who will respond to manipulation
were largely unsuccessful in doing so.
●The best univariate predictor of success with ma-
nipulation was the duration of the current symp-
toms; more acute symptoms were more likely to
respond favorably.
●Five variables were identified to form a clinical pre-
diction rule for patients with low back pain likely to
respond favorably to spinal manipulation: duration
of symptoms "16 days, FABQ work subscale score
"19, at least one hip with %35°of internal rotation
range of motion, hypomobility in the lumbar spine,
and no symptoms distal to the knee.
●The presence of four of five variables in the pre-
diction rule increased the likelihood of success with
manipulation from 45% to 95%.
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Appendix
Special Tests for SI Dysfunction
Procedure Criteria for Positive
Tests for symmetry
PSIS symmetry standing
17
Palpation of right and left PSIS with the patient standing One PSIS judged to be higher than the other
ASIS symmetry standing
17
Palpation of right and left ASIS with the patient standing One ASIS judged to be higher than the other
Iliac crest symmetry
standing
17
Palpation of right and left iliac crest with the patient standing One iliac crest judged to be higher than the other
Landmark symmetry
standing
17
Comparison of PSIS, ASIS, and iliac crest findings in standing All landmarks are not level and all landmarks are
not high on the same side
PSIS symmetry sitting
13
Palpation of right and left PSIS with the patient sitting One PSIS judged to be higher than the other
Pubic tubercle symmetry
supine
29
Palpation of the right and left tubercle with the patient supine One pubic tubercle judged to be higher than the
other
Ischial tuberosity symmetry
in prone
29
Palpation of the right and left ischial tuberosity with the
patient prone
One ischial tuberosity judged to be higher than
the other
Motion tests
Standing flexion test
13,62
The patient is standing and the relative heights of the PSIS
are assessed. The patient is asked to flex forward as far as
possible, with the examiner continuing to palpate the PSIS.
A change in the relative relationship of the PSIS
is found in the fully flexed position.
Seated flexion test
17,62
The patient is seated and the relative heights of the PSIS are
judged. The patient is asked to bend forward as far as
possible, with the examiner continuing to palpate the PSIS.
A change in the relative relationship of the PSIS
is found in the fully flexed position.
Long-sitting test
4,13
The patient is supine with hips and knees extended. The
examiner grasps around each ankle with the thumbs below
the medial malleoli. A visual estimation of leg length is
made. The patient is assisted to a long-sitting position, and
the examiner reexamines the relative leg lengths.
A change in the relative position of medial
malleoli occurs.
Prone knee bend test
12, 17
The patient is prone. The relative leg lengths are assessed by
looking at the heels. The examiner passively flexes the
patient’s knees to approximately 90°. The relative leg
lengths are assessed a gain in this position
A change in relative lengths occurs between the
two positions.
Gillet test
50
The patient is standing. The examiner places one thumb
under the PSIS on the side being tested, with the other
thumb over the S2 spinous process. The patient is
instructed to stand on one leg and flex the other hip and
knee, bringing the leg toward the chest.
The PSIS fails to move posterior and inferior with
respect to S2.
Patrick test—range of
motion
9,50
The patient is placed in the test position by flexing, abducting,
and externally rotating the hip of the tested leg, placing the
lateral malleolus on the knee of the opposite leg.
Overpressure is applied to the medial aspect of the knee.
The amount of motion available in the tested extremity is
compared with the opposite side.
A difference in the range of motion exists
between the two sides.
Provocation tests
Gaenslen test
26,45,50
The patient is supine with both legs extended. The leg being
tested is passively brought into full hip and knee flexion,
while the opposite hip is maintained in an extended
position. Overpressure is applied to the flexed extremity.
Pain is reproduced in either SI joint region with
performance of the test.
Posterior shear test
9,26,50
The patient is supine. The hip is flexed to 90°and adducted.
The examiner applies an axial force through the femur at
different angles of hip adduction–abduction.
Buttock pain is produced.
Compression/distraction
test
26,50
The patient is supine. Pressure is applied first in a posterior
and lateral direction (compression) on the ASIS
simultaneously. Pressure is then applied in an anterior and
medial direction on the ASIS (distraction).
Pain is reproduced in the SI joint region with
either maneuver.
Patrick test—Buttock pain
26
The patient’s hip is flexed, abducted, and externally rotated
by placing the lateral malleolus on the knee of the opposite
leg. Overpressure is applied to the medial aspect of the
knee while the pelvis is stabilized.
Buttock or low back pain is produced.
Patrick test—Groin pain
26
Same as above. Groin pain is produced.
Resisted hip abduction
9
The patient is supine with the hip in about 30°of abduction.
The examiner pushes the leg medially to cause an
isometric contraction of the hip abductors.
Buttock pain is produced.
Sacral sulcus test
21
The patient is prone. The examiner palpates with firm
pressure in the region directly medial to the PSIS.
Pain is reproduced in the SI region.
Sacral thrust test
26
The patient is prone. The examiner delivers an anteriorly
directed thrust directly over the sacrum.
Pain is reproduced in the SI region.
ASIS !anterior superior iliac spine; PSIS !posterior superior iliac spine; SI !sacroiliac.
2843Clinical Prediction Rule for Spinal Manipulation •Flynn et al
