clinical prediction rule to identify patients likely to responde to lumbar spine stabilization...

8/12/2019 Clinical Prediction Rule to Identify Patients Likely to Responde to Lumbar Spine Stabilization Exercisess: A Random

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6 | january2014 | volume44 | number1 | journaloforthopaedic&sportsphysicaltherapy

Low back pain (LBP) is

common among the generalpopulation, with a lifetimeprevalence and point pre-

valence estimated to be greaterthan 80% and 28%, respectively.12

Although short-term outcomes are gen-

erally favorable, some patients go on to

experience long-term pain and disabil-

ity,32,40,78and recurrence rates are high.17,78

Systematic reviews of various physi-

cal therapy interventions for LBP do not

provide strong support for any particu-

lar treatment approach.2,50,51,77 One pos-

sible reason is the use of heterogeneous

samples of patients in many clinical trials

for LBP. Patients with LBP demonstrate

both etiologic and prognostic hetero-geneity,7,40,45which makes it unlikely for

any single intervention to have a signifi-

cant advantage over another in a general

population with LBP. Classifying patients

into more homogeneous subgroups has

been previously identified as a top re-

STUDY DESIGN:Randomized controlled trial.

OBJECTIVE:To determine the validity of apreviously suggested clinical prediction rule (CPR)

for identifying patients most likely to experience

short-term success following lumbar stabilization

exercise (LSE).

BACKGROUND:Although LSE is commonlyused by physical therapists in the management

of low back pain, it does not seem to be more

effective than other interventions. A 4-item CPR

for identifying patients most likely to benefit from

LSE has been previously suggested but has yet to

be validated.

METHODS:One hundred five patients with

low back pain underwent a baseline examination

to determine their status on the CPR (positive or

negative). Patients were stratified by CPR status

and then randomized to receive an LSE program

or an intervention consisting of manual therapy

(MT) and range-of-motion/flexibility exercises.

Both interventions included 11 treatment sessions

delivered over 8 weeks. Low back painrelated

disability was measured by the modified version of

the Oswestry Disability Index at baseline and upon

completion of treatment.

RESULTS:The statistical significance for the2-way interaction between treatment group and

CPR status for the level of disability at the end

of the intervention was P= .17. However, amongpatients receiving LSE, those with a positive CPR

status experienced less disability by the end of

treatment compared with those with a nega-

tive CPR status (P= .02). Also, among patients

with a positive CPR status, those receiving LSE

experienced less disability by the end of treatment

compared with those receiving MT (P= .03). In

addition, there were main effects for treatment and

CPR status. Patients receiving LSE experienced

less disability by the end of treatment compared to

patients receiving MT (P= .05), and patients with

a positive CPR status experienced less disability

by the end of treatment compared to patients with

a negative CPR status, regardless of the treatment

received (P= .04). When a modified version of

the CPR (mCPR) containing only the presence of

aberrant movement and a positive prone instability

test was used, a significant interaction with treat-

ment was found for final disability (P= .02). Of the

patients who received LSE, those with a positive

mCPR status experienced less disability by the endof treatment compared to those with a negative

mCPR status (P= .02), and among patients with

a positive mCPR status, those who received LSE

experienced less disability by the end of treatment

compared to those who received MT (P= .005).

CONCLUSION:The previously suggested CPRfor identifying patients likely to benefit from LSE

could not be validated in this study. However, due

to its relatively low level of power, this study could

not invalidate the CPR, either. A modified version

of the CPR that contains only 2 items may possess

a better predictive validity to identify those most

likely to succeed with an LSE program. Because

this modified version was established through posthoc testing, an additional study is recommended

to prospectively test its predictive validity.

LEVEL OF EVIDENCE:Prognosis, level 1b. JOrthop Sports Phys Ther 2014;44(1):6-18. Epub 21

November 2013. doi:10.2519/jospt.2014.4888

KEY WORDS:lumbar spine, manual therapy

1Department of Physiotherapy, Ariel University, Ariel, Israel. 2Bat-Yamon Physical Therapy Clinic, Clalit Health Services, Israel. 3Giora Physical Therapy Clinic, Clalit Health

Services, Israel. 4Department of Physical Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel. This study was approved by the Helsinki

Committee of Clalit Health Services. The authors certify that they have no affiliations with or financial involvement in any organization or entity with a direct financial interest

in the subject matter or materials discussed in the article. Address correspondence to Dr Alon Rabin, Ariel University, Department of Physiotherapy, Kiryat Hamada, PO Box 3,

Ariel, Israel. E-mail: [email protected] 2014 Journal of Orthopaedic & Sports Physical Therapy

ALON RABIN, DPT, PhD1 ANAT SHASHUA, BPT, MS2 KOBY PIZEM, BPT3

RUTHY DICKSTEIN, PT, DSc4 GALI DAR, PT, PhD4

A Clinical Prediction Rule to IdentifyPatients With Low Back Pain Who AreLikely to Experience Short-Term Success

Following Lumbar Stabilization Exercises:A Randomized Controlled Validation Study

[RESEARCHREPORT]

Copyright2014JournalofOrthopaedic&S

po

rtsPhysicalTherapy.Allrightsreserved.
mailto:[email protected]:[email protected]:[email protected]


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journal of orthopaedic &sports physical therapy | volume 44 | number 1 | january 2014 | 7

search priority,6and, in fact, more recent

research has suggested that matching pa-

tients with interventions based on their

specific clinical presentation may yield

improved clinical outcomes.8,10,15,27,47Structural as well as functional

impairments, such as decreased and

delayed activation of the transversus ab-

dominis and atrophy of the lumbar mul-

tifidus,25,34,37,48,69,80 have been identified

among patients with LBP. These impair-

ments may result in a reduction in spinal

stiffness82and possibly render the spine

more vulnerable to excessive deforma-

tion and pain. Lumbar stabilization ex-

ercises (LSE) attempt to address these

impairments by retraining the properactivation and coordination of trunk

musculature.58,64 Stabilization exercises

are widely used by physical therapists in

the management of LBP.8,11,22,24,35,44,49,50,62,65

Although some evidence exists to support

the remediating effects of LSE on some

of the muscle impairments identified in

patients with LBP,36,73,74 the clinical ef-

ficacy of this intervention seems to vary.

When compared to sham or no interven-

tion, LSE appears to be advantageous22,65;

however, when compared to other exer-cise interventions or to manual therapy

(MT), no definitive advantage has been

ascertained.11,24,35,44,49,50,62,75

In light of the variable clinical suc-

cess of LSE and in accordance with the

aforementioned need to classify patients

who have LBP into more homogeneous

subgroups, Hicks et al33suggested a clini-

cal prediction rule (CPR) to specifically

identify patients with LBP who are likely

to exhibit short-term improvement with

LSE. Four variables were found to pos-sess the greatest predictive power for

treatment success: (1) age less than 40

years, (2) average straight leg raise (SLR)

of 91 or greater, (3) the presence of aber-

rant lumbar movement, and (4) a positive

prone instability test.33When at least 3

of the 4 variables were present, the posi-

tive likelihood ratio for achieving a suc-

cessful outcome was 4.0, increasing the

probability of success from 33% to 67%.33

The study by Hicks et al33comprises the

first stage in establishing a CPR, the deri-

vation stage.4,14,55Following derivation, a

CPR must be validated, that is, shown to

consistently predict the outcome of inter-

est in a separate and preferably prospec-tive investigation.26Given its preliminary

nature, and because CPRs do not typi-

cally perform as well on new samples of

patients,21,30,67,68modification of the CPR

may also be necessary to achieve satisfac-

tory predictive validity. Once validated,

CPRs can move into the final stage of

their determination, which includes an

investigation into their impact on clini-

cal practice (impact analysis).4,14,55

Validation of the CPR for LSE re-

quires a randomized controlled trial inwhich patients with a different status on

the CPR (positive or negative) undergo

an LSE program, as well as a comparison

intervention.4 The use of a comparison

intervention is important to determine

whether the CPR can truly identify pa-

tients who will benefit specifically from

LSE, as opposed to patients who have a

favorable prognosis irrespective of the

treatment received.66Finally, to validate

the CPR in the most clinically meaning-

ful manner, we believe that the compari-son intervention should be considered a

viable alternative to LSE, rather than a

sham or an inert intervention.

Manual therapy is an intervention fre-

quently used by physical therapists in the

management of patients with LBP39,46,56

and is recommended by several clinical

practice guidelines and systematic reviews

for the management of acute, subacute,

and chronic LBP.1,9,19,76These factors, com-

bined with the fact that LSE programs

have previously demonstrated variedlevels of success compared to MT,11,24,50,62

suggest that MT may be a suitable com-

parison intervention for testing the validi-

ty of the CPR. In contrast to its use among

heterogeneous samples,11,24,50,62 LSE

should demonstrate a clearer advantage

among patients with LBP who also satisfy

the CPR, if the CPR accurately identifies

the correct target patient population.

The purpose of this investigation was

to determine the validity of, or to possibly

modify, the previously suggested CPR for

identifying patients most likely to benefit

from LSE. We hypothesized that among

patients receiving LSE, those with a posi-

tive CPR status would exhibit a betteroutcome compared to those with a nega-

tive CPR status. We also hypothesized

that among patients with a positive CPR

status, those who received LSE would ex-

hibit a better outcome compared to those

who received MT.

METHODS

Patients

One hundred five patients diag-

nosed with LBP and referred tophysical therapy at 1 of 5 outpa-

tient clinics of Clalit Health Services in

the Tel-Aviv metropolitan area, Israel,

were recruited for this study. Subjects

were included if they were 18 to 60 years

of age, had a primary complaint of LBP

with or without associated leg symptoms

(pain, paresthesia), and had a minimum

score of 24% on the Hebrew version of

the modified Oswestry Disability Index

(MODI) outcome measure. Patients

were excluded if they presented with ahistory suggesting any red flags (eg, ma-

lignancy, infection, spine fracture, cauda

equina syndrome); 2 or more signs sug-

gesting lumbar nerve root compression,

such as decreased deep tendon reflexes,

myotomal weakness, decreased sensation

in a dermatomal distribution, or a posi-

tive SLR, crossed SLR, or femoral nerve

stretch test; or a history of corticosteroid

use, osteoporosis, or rheumatoid arthri-

tis. Patients were also excluded if they

were pregnant, received chiropracticor physical therapy care for LBP in the

preceding 6 months, could not read or

write in the Hebrew language, or had a

pending legal proceeding associated with

their LBP. Prior to participation, all pa-

tients signed an informed consent form

approved by the Helsinki Committee of

Clalit Health Services.

TherapistsSixteen physical therapists were involved


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[RESEARCHREPORT]

in the study. Eleven therapists, with be-

tween 4 and 12 years of experience in

outpatient physical therapy patient care,

provided treatment, and 5 therapists,

with between 13 to 25 years of experi-ence, performed baseline and follow-

up evaluations. Prior to beginning the

study, all participating therapists under-

went two 4-hour sessions in which the

rationale and protocol of the study were

presented and the examination and treat-

ment procedures were demonstrated and

practiced. Therapists had to pass a writ-

ten examination of the study procedures

prior to data collection. Finally, each

therapist received a manual describing

treatment and evaluation procedures,based on the therapists role in the study

(treatment or evaluation). Therapists in-

volved in treating patients were unaware

of the concept of the CPR throughout the

study, to avoid bias from this knowledge

during treatment. All treating therapists

provided both treatments of the study

(LSE and MT).

ProcedureAfter giving consent, patients completed

a baseline examination that included de-mographic information, an 11-point (0-

10) numeric pain rating scale (NPRS),

on which 0 was no pain and 10 was

the worst imaginable pain, the Hebrew

version of the MODI,3,28and the Hebrew

version of the Fear-Avoidance Beliefs

Questionnaire. 38,79 In addition, the his-

tory of the present and any past LBP

was documented, followed by a physical

examination.

The physical examination included a

neurological screen to rule out lumbarnerve root compression; lumbar active

motion, during which the presence of ab-

errant movement, as defined by Hicks et

al,33was determined; bilateral SLR range

of motion; segmental mobility of the lum-

bar spine; and the prone instability test.

The patients status on the CPR (positive

or negative) was established based on the

findings of the physical examination.

Examiners who performed the base-

line examinations, as well as examiners

who screened patients for eligibility to

participate in the study, were blinded to

the intervention allocation of the patients.

ReliabilityThe reliability of the individual physical

examination items comprising the CPR,

as well as that of the entire CPR, has been

reported previously.60In that study,60the

interrater reliability for determining CPR

status was excellent (= 0.86), and the

interrater reliability of each of the items

comprising the CPR ranged from moder-

ate to substantial (= 0.64-0.73).60

Randomization

At the conclusion of the physical exami-nation, each patient was randomized to

receive LSE or MT. Randomization was

based on a computer-generated list of

random numbers, stratified by CPR status

to ensure that adequate numbers of pa-

tients with a positive and a negative CPR

status would be included in each interven-

tion group. The list was kept by a research

assistant who was not involved in patient

recruitment, examination, or treatment.

InterventionPatients in both groups received 11 treat-ment sessions over an 8-week period.

Each patient was seen twice a week dur-

ing the first 4 weeks, then once a week

for 3 additional weeks. A 12th session

(usually on the eighth week) consisted

of a final evaluation. The total number

of sessions (12) matched the maximum

number of physical therapy visits allowed

annually per condition under the policy

of the Clalit Health Services health main-

tenance organization, which covered allpatients participating in the study. Pa-

tients in both groups were prescribed a

home exercise program consistent with

their treatment group; however, no at-

tempt was made to monitor patients

compliance with the home exercise

program.

Lumbar Stabilization ExercisesThe LSE program was largely based on

the program described by Hicks et al,33

with a few minor changes in the order of

the exercises and a few additional levels

of difficulty for some of the exercises. Pa-

tients were initially educated about the

structure and function of the trunk mus-culature, as well as common impairments

in these muscles among patients with

LBP. Patients were then taught to per-

form an isolated contraction of the trans-

versus abdominis and lumbar multifidus

through an abdominal drawing-in ma-

neuver (ADIM) in the quadruped, stand-

ing, and supine positions.63,64,69,71,73Once

a proper ADIM was achieved (most likely

by the second or third visit), additional

loads were placed on the spine through

various upper extremity, lower extremity,and trunk movement patterns. Exercises

were performed in the quadruped, sidely-

ing, supine, and standing positions, with

the goal of recruiting a variety of trunk

muscles.18,53,54In each position, exercises

were ordered by their level of difficulty,

and patients progressed from one exer-

cise to the next after satisfying specific

predetermined criteria. In the seventh

treatment session, functional movement

patterns were incorporated into the

training program while performing anADIM and maintaining a neutral lumbar

spine. This stage, which was not includ-

ed in the derivation study, was added to

the program because it has been recom-

mended by others.22,58,62The exercises in

each stage of the LSE program, as well as

the specific criteria for progression from

one exercise to the next, are outlined in

APPENDIX A(available atwww.jospt.org).

Manual Therapy

The MT intervention included severalthrust and nonthrust manipulative tech-

niques directed at the lumbar spine that

have been used previously with some

degree of success in various groups with

LBP.10,15,20,59In addition, manual stretch-

ing of several hip and thigh muscles was

performed, as flexibility of the lower ex-

tremity is purported to protect the spine

from excessive strain.54 Finally, active

range-of-motion and stretching exercis-

es were added to the program, as these


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are commonly prescribed in combina-

tion with MT to maintain or improve the

mobility gains resulting from the manual

procedures.10,15,20,47The exercises included

were selected to minimize trunk muscleactivation and to avoid duplication be-

tween the 2 interventions.

All manual procedures and exercises

were prescribed based on the clinical

judgment of the treating therapist; how-

ever, each session could include up to 3

manual techniques, 1 of which had to be

a thrust manipulative technique directed

at the lumbar spine, and an additional

technique that had to include a manual

stretch of a lower extremity muscle. The

third technique, as well as the comple-mentary range-of-motion/flexibility ex-

ercises, was given at the discretion of the

treating therapist. The MT techniques, as

well as all exercises used in the MT proto-

col, are described in APPENDIX B(available

atwww.jospt.org).

EvaluationThe MODI served as the primary out-

come measure in this investigation. The

MODI is scored from 0 to 100 and has a

minimal clinically important difference(MCID) of 10 points among patients with

LBP.57The secondary outcome measure

was the NPRS, which has an MCID of 2

points among patients with LBP.16Both

measures were administered before the

beginning of treatment and immediately

after the last treatment session by an in-

vestigator not involved in patient care.

Sample SizeSample size was calculated to detect a be-

tween-group difference of 12 points in thefinal score of the MODI, based on the in-

teraction between treatment group (LSE

versus MT) and CPR status (positive ver-

sus negative), with an alpha level of .05

and a power of 70%. Based on a 16-point

standard deviation, it was determined

that 20 patients were needed in each cell.

Pilot data suggested that the prevalence

of patients with a positive status on the

CPR was approximately 33%. Therefore,

it was estimated that 120 patients would

be necessary to include 40 patients with

a positive CPR status; however, 40 such

patients were included after 105 patients

were recruited, and recruitment was

stopped at that point.

Statistical AnalysisDescriptive statistics, including frequen-

cy counts for categorical variables and

measures of central tendency and dis-

persion for continuous variables, were

used to summarize the data. All baseline

variables were assessed for normal distri-

bution using the Shapiro-Wilk test. Base-

line variables were compared between

treatment groups (LSE versus MT), CPR

status (positive versus negative), andthe resulting 4 subgroups using a 2-way

analysis of variance and chi-square tests

for continuous and categorical variables,

respectively.

The primary aim of the study was

tested using 2 separate analyses of cova-

riance (ANCOVAs), with the final MODI

score serving as the dependent variable in

1 model and the final NPRS score serving

as the dependent variable in the second

model. In both models, treatment group

and CPR status served as independentvariables, and the baseline MODI score

(or baseline NPRS score) was used as

a covariate. The residuals of all models

were tested for violations of the ANCOVA

assumptions and for outliers. The main

effects of treatment group and CPR sta-

tus, as well as the 2-way interaction be-

tween these factors on the final MODI

and NPRS scores, were evaluated. The a

priori level of significance for these analy-

ses wasP.05. Two pairwise comparisons

were planned following the ANCOVA: (1)a comparison of differences between pa-

tients with a positive CPR receiving LSE

and those with a negative CPR receiving

LSE, and (2) a comparison of differences

between patients with a positive CPR

receiving LSE and those with a positive

CPR receiving MT. These 2 comparisons

were deemed the most relevant for the

purpose of validating the CPR, as both

included a comparison between patients

receiving a matched intervention (CPR-

positive patients receiving LSE) and

patients receiving an unmatched inter-

vention (either CPR-negative patients

receiving LSE or CPR-positive patients

receiving MT).The individual items of the CPR, as

well as different combinations of these

items, were similarly tested to identify

whether any such combination would

enhance the predictive validity of the

original version. Finally, the outcome was

also dichotomized as successful or unsuc-

cessful based on a previously established

cutoff threshold of 50% reduction in the

baseline score of the MODI.33The pro-

portion of patients achieving a success-

ful outcome was compared among theresulting subgroups (LSE CPR+, LSE

CPR, MT CPR+, and MT CPR) using

chi-square analysis.

An intention-to-treat approach was

performed for all analyses by using mul-

tiple imputations for any missing val-

ues of the 2 outcome measures (MODI,

NPRS). First, Littles missing completely

at random test was performed to test the

hypothesis that missing values were ran-

domly distributed. If this hypothesis could

not be rejected, expectation maximizationwas used to predict missing values. A per-

protocol analysis was performed as well.

All statistical analyses were performed us-

ing the JMP Version 10 statistical package

(SAS Institute Inc, Cary, NC), as well as

the SPSS Version 19 statistical package

(SPSS Inc, Chicago, IL).

RESULTS

Five hundred thirty-one poten-

tial candidates were screened foreligibility between March 2010 and

April 2012. Two hundred ninety-seven pa-

tients did not meet the inclusion criteria,

and another 129 declined participation.

The remaining 105 patients were admit-

ted into the study. Forty patients had a

positive CPR status, whereas 65 had a

negative status. Forty-eight patients were

randomized to the LSE group, whereas 57

patients were randomized to receive MT.

All patients underwent treatment accord-


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[RESEARCHREPORT]

ing to their allocated treatment group.

Sixteen patients did not complete the

LSE intervention, and 8 patients did not

complete the MT intervention (P= .02).

FIGURE 1presents patient recruitment and

retention throughout the study.

TABLE 1presents baseline demographic,

history, and self-reported variables for all

groups and subgroups. All baseline vari-

ables were normally distributed, with theexception of body mass index and dura-

tion of LBP. Log transformations were

thus performed on body mass index and

duration of LBP, resulting in a better dis-

tribution pattern. As a result, the geomet-

ric mean with 95% confidence interval is

reported for these variables, as opposed

to meanSD for all other baseline vari-

ables (TABLE 1). No baseline differences

were noted between the different groups

and subgroups other than for age. Pa-

tients with a positive CPR status were

younger than patients with a negative

CPR status (P= .0006). This difference

was expected, as 1 of the items comprising

the CPR is being less than 40 years of age.

Therefore, we did not correct our model

to account for this expected difference.

Littles "missing completely at ran-

dom" test indicated that the hypothesis

that final MODI and NPRS scores wererandomly missing could not be rejected

(P= .76 for the MODI and P= .52 for the

NPRS). Therefore, expectation maximi-

zation was used to replace missing values.

Completers Versus NoncompletersAll baseline demographic, history, and

self-reported variables were compared

between patients who completed the

intervention (completers, n = 81) and

patients who dropped out prior to com-

pleting the intervention (noncompleters,

n = 24) using Wilcoxon and Fisher ex-

act tests for continuous and categorical

variables, respectively. Noncompleters

exhibited a higher baseline score onthe Fear-Avoidance Beliefs Question-

naire physical activity subscale versus

completers (17.2 versus 15.1, P = .04).

Noncompleters also had a lower level

of education compared to completers

(P = .03). No other differences were

detected between the completers and

noncompleters.

Analysis by Intention to TreatThe baseline and final MODI and NPRS

scores for each treatment group and sub-group are summarized in TABLE 2. When

assessing final disability level, the statisti-

cal level of significance for the 2-way in-

teraction between treatment group and

CPR status wasP= .17. A main effect was

detected for treatment (P= .05), which

indicated that patients receiving LSE

experienced less disability by the end

of treatment compared to the patients

who received MT. A main effect was also

detected for CPR status (P= .04), indi-

cating that patients with a positive CPRstatus experienced less disability by the

end of treatment compared to those with

a negative CPR status, regardless of the

treatment received. The 2 preplanned

pairwise comparisons indicated that (1)

among patients receiving LSE, those with

a positive CPR status experienced less dis-

ability at the end of the intervention com-

pared to those with a negative CPR status

(P= .02); and (2) among patients with a

positive CPR status, those receiving LSE

experienced less disability by the endof treatment compared to those receiv-

ing MT (P= .03). The change in MODI

between baseline and the end of treat-

ment for the 4 subgroups is represented

in FIGURE 2. No interactions or main ef-

fects were noted for pain (P>.26). TABLE 3

presents the adjusted final disability and

pain scores for all groups and subgroups,

and TABLE 4presents the differences in fi-

nal disability and pain among the differ-

ent groups and subgroups.

Screened for eligibility, n = 531

Randomized, n = 105

Lumbar stabilization exercises,n = 48

Excluded, n = 297:

MODI


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The proportion of patients who

achieved a successful outcome, defined

as a reduction of at least 50% in disability

as measured by the MODI, did not differ

among the 4 subgroups (P= .31) (FIGURE 3

).When examining the interaction of

treatment group with each of the indi-

vidual items comprising the CPR on fi-

nal disability, no significant effects were

noted (aberrant movement,P= .07; prone

instability test, P= .16; age less than 40

years,P= .72; SLR of 91 or greater, P=

.79). However, when combining the pres-

ence of aberrant movement and a positive

prone instability test (n = 44), a signifi-

cant 2-way interaction between treatment

group and the modified version of the CPR

(mCPR) was found for final disability (P

= .02). When the 2 pairwise comparisons

were repeated using the mCPR, findings

indicated that (1) among patients receiv-ing LSE, those with a positive mCPR sta-

tus (n = 20) experienced less disability by

the end of treatment compared to those

with a negative mCPR status (n = 28,P=

.02); and (2) among patients with a posi-

tive mCPR status, those receiving LSE (n

= 20) experienced less disability by the

end of treatment compared to those re-

ceiving MT (n = 24,P= .005). Unlike the

original version of the CPR, the mCPR

did not demonstrate a main effect for fi-

nal disability (P= .27). No 2-way interac-

tion or main effects were noted for final

pain level when using the mCPR (P>.09).

TABLE 5presents the adjusted final disabil-

ity and pain scores of the different groupsand subgroups based on the mCPR, and

TABLE 6 presents the differences in final

disability and pain among the groups and

subgroups based on the mCPR.

Finally, the proportion of patients

achieving a successful outcome did not

differ between the subgroups based on

mCPR status (P= .30) (FIGURE 4).

Per-Protocol AnalysisSimilar to analysis by intention to treat,

TABLE 1 Baseline Demographic, History, and Self-Report Variables for All Groups

Abbreviations: BMI, body mass index; CPR, patients with a negative status on the clinical prediction rule; CPR+, patients with a positive status on the clini-cal prediction rule; FABQ-PA, Fear-Avoidance Beliefs Questionnaire physical activity subscale; FABQ-W, Fear-Avoidance Beliefs Questionnaire work subscale;

LBP, low back pain; LSE, patients treated with lumbar stabilization exercises; MODI, modified Oswestry Disability Index; MT, patients treated with manual

therapy; NPRS, numeric pain rating scale.

*Values are meanSD.CPR greater than CPR+ (P = .0006).Values are mean (95% confidence interval).Numbers provided when data not available on all patients.

Characteristic LSE (n = 48) MT (n = 57) CPR+ (n = 40) CPR (n = 65)LSE CPR+(n = 18)

LSE CPR(n = 30)

MT CPR+(n = 22)

MT CPR(n = 35)

Sex (female), n (%) 25 (52.1) 31 (54.4) 22 (55.0) 34 (52.3) 10 (55.6) 15 (50.0) 12 (54.5) 19 (54.3)

Age, y* 38.310.5 35.59.1 32.87.5 39.210.3 32.77.4 41.610.7 32.87.7 37.29.6

BMI, kg/m2 24.4 (22.9, 25.9) 25.8 (24.3, 27.3) 24.2 (22.6, 25.9) 25.9 (24.7, 27.3) 22.9 (20.7, 25.4) 25.9 (24.0, 27.9) 25.6 (23.3, 28.1) 26.0 (24.3, 27.8)

Education, n (%)

Less than high school 2 (4.2) 0 (0) 0 (0) 2 (3.1) 0 (0) 2 (6.7) 0 (0) 0 (0)

High school 21 (43.7) 15 (26.3) 9 (22.5) 27 (41.5) 5 (27.8) 16 (53.3) 4 (18.2) 11 (31.4)

Some postsecondary 8 (16.7) 15 (26.3) 9 (22.5) 14 (21.5) 3 (16.7) 5 (16.7) 6 (27.3) 9 (25.7)

Bachelor 13 (27.1) 17 (29.8) 18 (45.0) 12 (18.5) 8 (44.4) 5 (16.7) 10 (45.5) 7 (20.0)

Master 3 (6.2) 9 (15.8) 4 (10.0) 8 (12.3) 2 (11.1) 1 (3.3) 2 (9.0) 7 (20.0)

Doctorate 1 (2.1) 1 (1.8) 0 (0) 2 (3.1) 0 (0) 1 (3.3) 0 (0) 1 (2.8)

Work status (employed),

n (%)

38/43 (88.4) 41/53 (77.4) 28/36 (77.8) 51/60 (85.0) 13/16 (81.3) 25/27 (92.6) 15/20 (75.0) 26/33 (78.8)

Smoker, n (%) 16/44 (36.4) 11/53 (20.8) 14/36 (38.9) 13/61 (21.3) 8/16 (50.0) 8/28 (28.6) 6/20 (30.0) 5/33 (15.2)

Duration (days since

onset)58.7 (41.8, 82.4) 67.4 (48.9, 92.9) 63.8 (44.2, 92.2) 62.0 (46.5, 82.7) 52.0 (30.5, 88.6) 66.3 (43.6, 101.0) 78.4 (47.3, 130.0) 57.9 (39.1, 85.9)

Use of analgesics, n (%) 22/42 (52.4) 32/53 (60.4) 23/36 (63.9) 31/59 (52.5) 9/16 (56.3) 13/26 (50.0) 14/20 (70.0) 18/33 (54.6)

Past LBP, n (%) 34/48 (70.8) 35/56 (62.5) 27/39 (69.2) 42/65 (64.6) 13/18 (72.2) 21/30 (70.0) 14/21 (66.7) 21/35 (60.0)

Symptoms below knee,

n (%)

14 (29.2) 16 (28.1) 8 (20.0) 22 (33.8) 2 (11.1) 12 (40.0) 6 (27.3) 10 (28.6)

NPRS (0-10)* 4.91.7 5.31.7 4.91.7 5.31.7 4.41.7 5.21.6 5.21.6 5.41.8

MODI (0-100)* 37.810.6 37.612.5 40.012.8 36.310.6 37.89.4 37.711.4 41.815.0 35.09.9

FABQ-PA (0-24)* 16.24.4 15.14.9 14.95.3 16.04.3 15.94.3 16.34.6 14.15.8 15.74.2

FABQ-W (0-42)* 18.19.9 19.410.3 19.910.5 18.19.9 18.911.0 17.69.4 20.710.3 18.610.4


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dated in our investigation. Nevertheless,

we believe the CPR may hold promise in

identifying patients most likely to experi-

ence success following LSE. Despite the

absence of a CPR-by-treatment interac-

tion, the 2 pairwise comparisons most

relevant for validating the CPR indicated

that, by the end of treatment, patients

with a positive CPR status who received

LSE (a matched intervention) experi-

enced less disability compared to thosewith a negative CPR status receiving

LSE or to patients with a positive CPR

status receiving MT (an unmatched in-

tervention). Furthermore, effect sizes for

both of these comparisons were very close

to the MCID of the MODI (10 points),

and the lower bounds of the 95% confi-

dence intervals were above zero (TABLE 4).

The extra noise created by the multiple

computations of the ANCOVA might

have prevented a significant CPR-by-

treatment interaction effect, despite theconsistent advantage for patients with a

positive CPR treated with LSE.

It seems, therefore, that the inability

to validate the CPR in this study is most

likely related to its level of power. Our

a priori sample-size calculation was de-

signed to detect a 12-point difference in

the MODI, with = .05 and a power of

70%. Therefore, it could be argued that

our study was somewhat underpowered.

However, based on our findings, 314

patients would have been required to

achieve 80% power for detecting an in-

teraction between treatment group and

CPR status, a sample size that was un-

realistic under the circumstances of the

present study. We therefore believe that,

although our results cannot validate the

CPR, they do not invalidate it but, in fact,

seem to imply its potential. It is not un-

reasonable to assume that the CPR in its

current form may still be able to indicatewhich patients would most likely succeed

with LSE.

Among other potential reasons for

the inability to validate a CPR are dif-

ferences in sample characteristics, in the

application of the CPR itself, in the ad-

ministration of the intervention, and in

the definition of the outcome between the

derivation and validation studies. With

regard to sample characteristics, the in-

clusion/exclusion criteria in the current

study were fairly similar to those of thederivation study,33which resulted in rela-

tively similar samples. However, patients

in the current study demonstrated a high-

er level of disability at baseline (MODI

score, 37% versus 29% in the derivation

study33) and a somewhat longer duration

of symptoms (68 versus 40 days). The

longer duration of LBP in the current

sample could have had a negative effect

on the overall prognosis32,40,72; however,

this effect was not expected to differ be-

tween the treatment groups or subgroups.

As for the application of the CPR it-

self, the sample of the current study in-

cluded a higher proportion of patients

with a positive CPR status compared to

the derivation study (38% versus 28%).33

A likely reason for this difference is the

younger age of our sample (37 versus 42

years). Another possible reason is thehigher prevalence of a positive prone

instability test in our study (71% versus

52% in the derivation study33). Because

we used the same testing technique and

rating criteria as outlined by Hicks et al,33

we cannot explain the difference in prev-

alence rates of a positive prone instability

test. In any event, we do not believe that

the higher rate of a positive CPR status in

our study was likely to hinder the ability

to validate the CPR.

The LSE program used in the currentstudy was very similar to that used in the

derivation study. In addition, the criteria

for dichotomizing the outcomes as suc-

cess or failure were identical to those

used in the derivation study.33Therefore,

we do not believe these factors would

likely explain the inability to validate the

CPR, either.

Finally, the inability to validate the

CPR may be related to the comparison

intervention used in the current study.

TABLE 4

Baseline Adjusted Mean Differences in Final

Disability (MODI) and Pain (NPRS) Between

the Different Groups and Subgroups

Abbreviations: CPR, patients with a negative status on the clinical prediction rule; CPR+, patients

with a positive status on the clinical prediction rule; LSE, patients treated with lumbar stabilization

exercises; MODI, modified Oswestry Disability Index; MT, patients treated with manual therapy;

NPRS, numeric pain rating scale.

*Values are mean difference (95% confidence interval).Positive values indicate an advantage to LSE.Positive values indicate an advantage to CPR+.Positive values indicate an advantage to LSE CPR+.

Comparison MODI (0-100)* PValue NPRS (0-10)* PValue

LSE versus MT 5.0 (0.1, 9.9) .05 0.5 (0.3, 1.3) .26

CPR+ versus CPR 5.2 (0.2, 10.2) .04 0.1 (0.7, 0.9) .88

LSE CPR+ versus LSE CPR 8.7 (1.4, 15.9) .02 0.3 (0.9, 1.5) .67

LSE CPR+ versus MT CPR+ 8.5 (0.7, 16.3) .03 0.7 (0.6, 1.9) .31

010

LSE CPR+ LSE CPR MT CPR+ MT CPR

2030

405060708090

Succ

essRate,

%

FIGURE 3. Rate of success (%) among the 4

subgroups based on the original clinical prediction

rule and a cutoff threshold of 50% decrease in

baseline modified Oswestry Disability Index score.

Abbreviations: LSE CPR, patients with a negative

status on the clinical prediction rule treated with

lumbar stabilization exercises; LSE CPR+, patients

with a positive status on the clinical prediction rule

treated with lumbar stabilization exercises; MT

CPR, patients with a negative status on the clinical

prediction rule treated with manual therapy; MT

CPR+, patients with a positive status on the clinical

prediction rule treated with manual therapy.


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[RESEARCHREPORT]

Manual therapy seemed to be a suitable

comparison intervention because it is fre-quently used in the management of LBP,

it is advocated by several clinical practice

guidelines,1,19,76and it has previously been

shown to have a varied level of success

when compared to LSE in heterogeneous

samples of patients with LBP.11,24,50,62

Despite this rationale, recent evidence

suggests that spinal manipulation may

result in remediation of some muscle im-

pairments that are the focus of LSE pro-

grams, such as increased activation of the

transversus abdominis and lumbar mul-

tifidi.

42,61

It is possible, therefore, that themanipulation techniques included in the

MT intervention contributed to facilita-

tion of the deep spinal musculature and,

consequently, exerted an effect similar to

that attributed to LSE. Be that as it may,

when spinal manipulation has been pre-

viously performed specifically on patients

who meet the stabilization CPR,41no ef-

fects were observed on the activation of

the transversus abdominis or internal

oblique, and the clinical effects (pain and

disability) did not exceed the minimal

clinically important threshold.41Further-

more, another study indicated that none

of the variables comprising the stabiliza-

tion CPR was associated with increased

activation of the lumbar multifidus fol-

lowing spinal manipulation.43

Finally,any changes in activation of the lumbar

multifidus that were observed immedi-

ately after manipulation did not seem to

be consistently sustained 3 to 4 days after

the application of the technique.42There-

fore, we do not believe the manipulation

techniques in our study were likely to

produce long-lasting or clinically signifi-

cant changes in recruitment of the spinal

musculature of our patients.

During the process of CPR validation,

it is not unusual to attempt to modifyan original version of a CPR by adding,

omitting, or combining several of its

items.67,68,81 Our findings indicate that a

modified version of the CPR (mCPR),

containing only 2 of the original 4 items,

yielded a better predictive validity. The

mCPR did result in a significant inter-

action effect with treatment, and the 2

corresponding pairwise comparisons

indicated a better outcome for patients

with a positive mCPR status treated with

TABLE 5

BaselineAdjusted FinalDisability(MODI)

andPain(NPRS)AmongtheDifferentGroups

andSubgroupsBasedon themCPR*

Abbreviations: LSE, patients treated with lumbar stabilization exercises; mCPR, patients with a

negative status on the modified clinical prediction rule; mCPR+, patients with a positive status on the

modified clinical prediction rule; MODI, modified Oswestry Disability Index; MT, patients treated

with manual therapy; NPRS, numeric pain rating scale.*Values are mean (95% confidence interval) and are provided based on intention-to-treat analysis.

Group MODI (0-100) NPRS (0-10)

LSE (n = 48) 15.4 (11.8, 18.9) 2.5 (1.9, 3.0)

MT (n = 57) 20.4 (17.2, 23.7) 3.0 (2.5, 3.5)

mCPR+ (n = 44) 16.5 (12.8, 20.3) 2.7 (2.1, 3.3)

mCPR (n = 61) 19.3 (16.1, 22.4) 2.8 (2.3, 3.3)

LSE mCPR+ (n = 20) 11.2 (5.7, 16.6) 2.0 (1.1, 2.9)

LSE mCPR (n = 28) 19.6 (15.0, 24.2) 2.9 (2.1, 3.6)

MT mCPR+ (n = 24) 21.9 (16.9, 26.9) 3.3 (2.5, 4.1)

MT mCPR (n = 33) 19.0 (14.7, 23.2) 2.8 (2.1, 3.4)

TABLE 6

BaselineAdjusted MeanDifferences

in FinalDisability(MODI)andPain

(NPRS)BetweentheDifferentGroups

andSubgroupsBasedon themCPR

Abbreviations: LSE, patients treated with lumbar stabilization exercises; mCPR, patients with a

negative status on the modified clinical prediction rule; mCPR+, patients with a positive status on the

modified clinical prediction rule; MODI, modified Oswestry Disability Index; MT, patients treated

with manual therapy; NPRS, numeric pain rating scale.

*Values are mean difference (95% confidence interval) and are provided based on intention-to-treat

analysis.Positive values indicate an advantage to LSE.Positive values indicate an advantage to mCPR+.Positive values indicate an advantage to LSE (mCPR+).

Comparison MODI (0-100)* PValue NPRS (0-10)* PValue

LSE versus MT 5.0 (0.2, 9.9) .04 0.5 (0.2, 1.3) .18

mCPR+ versus mCPR 2.7 (2.2, 7.7) .27 0.2 (0.6, 1.0) .67

LSE mCPR+ versus LSE mCPR

8.4 (1.3, 15.5) .02 0.8 (0.3, 2.0) .16LSE mCPR+ versus MT mCPR+ 10.7 (3.4, 18.1) .005 1.2 (0.0, 2.4) .05

010

LSE mCPR+ LSE mCPR M T mCPR+ M T mCPR

2030

405060708090

SuccessRate,

%

FIGURE 4. Rate of success (%) among the 4

subgroups based on the mCPR and a cutoff

threshold of 50% decrease in baseline modified

Oswestry Disability Index score. Abbreviations:

LSE mCPR, patients with a negative status on the

modified clinical prediction rule treated with lumbar

stabilization exercises; LSE mCPR+, patients with

a positive status on the modified clinical prediction

rule treated with lumbar stabilization exercises;

mCPR, modified clinical prediction rule; MT mCPR,

patients with a negative status on the modified

clinical prediction rule treated with manual therapy;

MT mCPR+, patients with a positive status on the

modified clinical prediction rule treated with manual

therapy.


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LSE compared to patients treated with

unmatched interventions. Effect sizes

for these comparisons were either above

or slightly below the MCID of the MODI

(TABLE 6). These findings seem to suggestthat the mCPR may be a more accurate

predictor of success following LSE.

It is acknowledged that because the

mCPR was derived retrospectively, its

effect on final disability could have oc-

curred by chance alone. We believe, how-

ever, that several factors point against

this possibility. First, the mCPR is still

composed of items that have been previ-

ously linked to success following LSE in

the derivation study.33Second, no other

combination of items from the originalCPR produced similar findings. Third,

we believe this 2-item version may even

possess a clearer biomechanical plau-

sibility compared to the original CPR.

The mCPR status is considered positive

when both aberrant lumbar movement

and a positive prone instability test are

present. Teyhen et al70 demonstrated

that, compared to healthy individuals,

patients with LBP, aberrant movements,

and a positive prone instability test dem-

onstrate decreased control of lumbarsegmental mobility during midrange

lumbar motion.This difference may rep-

resent an altered motor control strategy,

which suggests that an LSE program may

be most beneficial under those circum-

stances. Furthermore, Hebert et al31dem-

onstrated that individuals with LBP and

a positive prone instability test displayed

decreased automatic activation of their

lumbar multifidi compared to healthy

controls. Given the remediating effects

of LSE on muscle activation patterns,

73,74

it seems reasonable that LSE would be

most beneficial for patients presenting

with such activation deficits. In contrast,

it seems much less clear why patients

under the age of 40 would preferentially

benefit from LSE as opposed to MT or

any other intervention. In fact, a younger

age has been previously associated with

a generally favorable prognosis following

an episode of LBP.5,13,29,52,72 This finding

may help to explain why the CPR in its

original version seemed to be consistently

associated with a better outcome, regard-

less of the treatment received. Likewise,

it seems less intuitive why a greater SLR

range of motion would predict a betteroutcome specifically following LSE.

Finally, our entire sample included 40

patients with a positive CPR status ac-

cording to the original (4-item) version

and 44 patients with a positive mCPR

status. It could therefore be argued that

the slightly larger number of patients

with a positive mCPR might have simply

increased the power to detect an inter-

action with treatment group. However,

as only 31 patients had a positive status

according to both versions of the CPR, itseems that the better predictive power of

the mCPR may not simply be a matter of

sample size but may be inherent in pa-

tients presenting with the 2 specific items

comprising the mCPR.

In summary, we believe that, in addi-

tion to its stronger statistical association

with success specifically following LSE,

the mCPR carries a stronger biomechani-

cal plausibility as a predictor of success

following this intervention. Nevertheless,

due to its retrospective nature, an addi-tional investigation is recommended to

prospectively establish the predictive va-

lidity of the mCPR.

Study LimitationsIn addition to the aforementioned issues

of power and the retrospective nature of

some of the findings, the current study

has several additional limitations. First,

the dropout rate was fairly high, in par-

ticular among the LSE group. Overall,

24 patients (22.8%) did not completethe study. The dropout rate was greater

among patients receiving LSE (33%

versus 14%). We believe that the overall

dropout rate of the current study may

partly reflect the dropout rate (31%)

among Israeli patients receiving outpa-

tient physical therapy for common mus-

culoskeletal conditions.23 The greater

dropout rate among the LSE group also

suggests that patients receiving this in-

tervention may not have perceived it to

be as valuable as MT. The manual contact

included in the MT intervention could

have created an attention effect in favor

of this intervention, which, in turn, might

have contributed to better compliance.Because this was suspected, the treating

clinicians were encouraged to provide

patients receiving LSE with continuous

verbal as well as manual cuing for main-

taining a neutral lumbar posture and an

ADIM. It seems, however, that this ap-

proach still failed to produce a similar

level of compliance among the 2 groups.

An intention-to-treat analysis was used

in an attempt to minimize the effect of

the dropout rate on our findings.

Longer-term outcomes should be as-sessed to determine whether the CPR

in its original or modified version has

any long-term effects on patients in the

various subgroups. In addition, the ex-

ternal validity of our findings needs to

be considered, as only 105 patients were

recruited after screening 531 potential

participants. Most participants were ex-

cluded for not meeting the minimal level

of disability required for inclusion (FIGURE

1). Therefore, findings are limited to pa-

tients with LBP with at least a moderatelevel of disability.

CONCLUSION

The previously suggested CPR

for identifying patients most likely

to succeed following LSE could not

be validated in this study. However, be-

cause the subgroup comparisons most

relevant for the validity of the CPR in-

dicated an advantage for patients with

a positive CPR treated by LSE, and be-cause of a relatively low level of power,

our findings suggest that the current CPR

still has the potential to predict success

following LSE. Furthermore, a modified

version of the original CPR that included

only 2 of its items (aberrant movement

and positive prone instability test) was

able to predict a successful outcome spe-

cifically following LSE and may serve as

a valid alternative. Future study is rec-

ommended to prospectively validate the


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[RESEARCHREPORT]

mCPR as a predictor of success with LSE

in individuals with LBP. Alternatively, to

validate the original version of the CPR, a

larger, replication study is recommended

in an attempt to overcome the insufficientpower of the current study. The findings

of this study are further limited by a rela-

tively large dropout rate (22.8%) and lack

of a long-term follow-up.

KEY POINTSFINDINGS:Although not validated, the

previously suggested CPR for identifying

patients most likely to succeed follow-

ing LSE shows promise. Furthermore, a

modified version of the CPR containing

only 2 of its original 4 items (presence ofaberrant movement and a positive prone

instability test) demonstrated a better

predictive validity in identifying those

most likely to succeed with LSE.

IMPLICATIONS:Patients with LBP present-

ing with aberrant lumbar movement as

well as a positive prone instability test

may benefit most from an LSE program.

CAUTION:Findings are limited by a

relatively small sample size, a relatively

large dropout rate, and the lack of a

long-term follow-up.

ACKNOWLEDGEMENTS: The authors thank Dr

Gregory Hicks, Arnon Ravid, Ori Firsteter,

Shai Grinberg, Efrat Laor, Dikla Taif, Alon

Ben-Moshe, Mossa Hugirat, Meira Lugasi,

Lena Oifman, Liron Laposhner, Beni Mazoz,

Fadi Knuati, Lena Kin, Ruthy Bachar, Chen

Tel-Avivi, Irit Fridman, Yana Avner, Naomi

Sivan, Rafi Cohen, and Yigal Levran for their

contribution and support of this work.

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clinical prediction rule to identify patients likely to responde to lumbar spine stabilization...

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