PHYSICAL THERAPY, CHIROPRAC TIC MANIPUL ATION, OR AN EDUCATIONAL BOOKLET FOR BACK PAIN

A COMPARISON OF PHYSICAL THERAPY, CHIROPRACTIC MANIPULATION,
AND PROVISION OF AN EDUCATIONAL BOOKLET FOR THE TREATMENT
OF PATIENTS WITH LOW BACK PAINDANIEL C. CHERKIN, PH.D., RICHARD A. DEYO, M.D., M.P.H., MICHELE BATTIÉ, PH.D., R.P.T.,
JANET STREET, M.N., C.P.N.P., AND WILLIAM BARLOW, PH.D.

ABSTRACT
Background and Methods There are few data on
the relative effectiveness and costs of treatments forlow back pain. We randomly assigned 321 adults
with low back pain that persisted for seven days after a primary care visit to the McKenzie method ofphysical therapy, chiropractic manipulation, or a minimal intervention (provision of an educational booklet). Patients with sciatica were excluded. Physicaltherapy or chiropractic manipulation was provided
for one month (the number of visits was determinedby the practitioner but was limited to a maximum ofnine); patients were followed for a total of two years.
The bothersomeness of symptoms was measured
on an 11-point scale, and the level of dysfunction
was measured on the 24-point Roland Disability Scale.
Results After adjustment for base-line differences, the chiropractic group had less severe symptoms than the booklet group at four weeks (P=0.02),
and there was a trend toward less severe symptoms
in the physical-therapy group (P=0.06). However,these differences were small and not significant after transformations of the data to adjust for their
non-normal distribution. Differences in the extent of
dysfunction among the groups were small and approached significance only at one year, with greaterdysfunction in the booklet group than in the othertwo groups (P=0.05). For all outcomes, there wereno significant differences between the physical-therapy and chiropractic groups and no significant differences among the groups in the numbers of daysof reduced activity or missed work or in recurrencesof back pain. About 75 percent of the subjects in thetherapy groups rated their care as very good or excellent, as compared with about 30 percent of thesubjects in the booklet group (P<0.001). Over a twoyear period, the mean costs of care were $437 for thephysical-therapy group, $429 for the chiropractic
group, and $153 for the booklet group.
Conclusions For patients with low back pain, theMcKenzie method of physical therapy and chiropractic manipulation had similar effects and costs, andpatients receiving these treatments had only marginally better outcomes than those receiving the minimal intervention of an educational booklet. Whether
the limited benefits of these treatments are worth
the additional costs is open to question. (N Engl J
Med 1998;339:1021-9.)©1998, Massachusetts Medical Society.

B

ACK pain is a major health problem because of its high prevalence1,2 and costs interms of health care expenditures3-5 and lost
productivity.6 Although there are many nonsurgical treatments, there is little evidence that any
are particularly effective. Systematic reviews have concluded that chiropractic spinal manipulation appears
to be effective in some subgroups of patients withback pain7-9 and this is one of the few treatments recommended in clinical-practice guidelines on the careof adults with low back pain in the United States.10
The effectiveness of physical therapy for back pain
has not been well studied, and the results of comparisons of physical therapy with chiropractic manipulation have conflicted.11-14 A popular form ofphysical therapy,15 the McKenzie method, has notbeen rigorously evaluated16 or compared with spinal
manipulation. We compared the effectiveness andcost of the McKenzie method of physical therapy,
chiropractic manipulation, and provision of an educational booklet for the treatment of low back pain.
METHODS
Study Sites
This study was conducted at Group Health Cooperative ofPuget Sound, a large staff-model health maintenance organization (HMO) in Washington. Subjects were recruited from two
Seattle-area primary care clinics between November 1993 andSeptember 1995. Physical therapy was provided in a facility adjacent to these clinics, and spinal manipulation was performed byfour chiropractors in solo practice. The study protocol was approved by the institutional review boards of Group Health Cooperative and the University of Washington, and all subjects gave
written informed consent.
Subjects
Patients 20 to 64 years of age who saw their primary care physician for low back pain and who still had pain seven days later
were eligible for the study. Physicians referred potential subjects
to a research assistant, who obtained consent and collected information on the subjects’ history of back pain, sociodemographic
characteristics, general health, and expectations of improvement.
General health was evaluated with the general health perceptions
and mental health subscales of the Medical Outcomes Study

From the Group Health Center for Health Studies (D.C.C., J.S., W.B.),
the Departments of Health Services (D.C.C., R.A.D.), Family Medicine(D.C.C.), Medicine (R.A.D.), and Biostatistics (W.B.) and the Center for
Cost and Outcomes Research (R.A.D.), University of Washington, Seattle;
and the Department of Physical Therapy, University of Alberta, Edmonton, Canada (M.B.). Address reprint requests to Dr. Cherkin at the Group
Health Center for Health Studies, 1730 Minor Ave., Suite 1600, Seattle,
WA 98101.

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Short-Form Health Survey (SF-36).17,18 The score on each of thesubscales ranges from 0 (worst) to 100 (best). Subjects were excluded if they had mild or no pain seven days after the visit to thephysician, a history of back surgery, sciatica, systemic or visceralcauses of the pain, osteoporosis, a vertebral fracture or dislocation, severe neurologic signs, spondylolisthesis, coagulation disorders, or a severe concurrent illness. Subjects who had received
corticosteroid therapy, were pregnant, were involved in claims forcompensation or litigation because of the back injury, had received physical therapy or chiropractic or osteopathic manipulative treatment for their current back pain, or visited practitioners
other than their primary care physicians were also excluded. Useof pain medications was not a reason for exclusion.
Randomization
After base-line data had been collected, the subjects were randomly assigned without stratification to receive physical therapy,
chiropractic manipulation, or an educational booklet with the useof sealed, opaque envelopes. Because a pilot study suggested atrend toward worse outcomes in the group that received thebooklet, but similar outcomes in the other two groups, we allocated 40 percent of subjects to physical therapy, 40 percent tochiropractic manipulation, and 20 percent to the educational
booklet.
Treatments
Because Washington laws prohibit physical therapists from performing spinal manipulation and chiropractors from using physical therapies such as ultrasonography, the clinical practices are
distinct.
Physical Therapy

In the McKenzie approach, patients are placed in one of threebroad categories (derangement, dysfunction, and postural syndrome) that determine therapy.19,20 In this formulation, mostback, buttock, and leg pain is thought to result from a “derangement syndrome,” treated by exercises that “centralize” pain fromthe feet, legs, or buttocks to the lower back.21 Patients are taught
to perform exercises that centralize their symptoms and to avoid
movements that peripheralize them. This method relies on patient-generated forces and emphasizes self-care.
Physical therapy was provided by 13 therapists with a medianof 14 years of experience. McKenzie Institute faculty trained thetherapists before the study, and all but one therapist passed anadvanced McKenzie credentialing examination. Subjects received
McKenzie’s Treat Your Own Back book19 and a lumbar-supportcushion. Therapists were asked to avoid adjuncts such as heat, ice,transcutaneous electrical nerve stimulation, ultrasonography, andback classes. The first visit was scheduled within four days after
randomization, and up to eight more visits were scheduled, at thediscretion of the therapist, over the ensuing month.
Chiropractic Manipulation

The most common method of chiropractic manipulation 22 wasused: a short-lever, high-velocity thrust directed specifically at a
“manipulable lesion.” This procedure is typically performed withthe patient lying on his or her side on a segmental table. No otherphysical treatments were permitted. Chiropractors evaluated patients according to their usual procedures and were allowed tomake the same recommendations about exercise and activity restrictions that they usually did. An exercise sheet was used thatemphasized stretching and strengthening but excluded extension
exercises, an important part of McKenzie therapy. The HMO
gave the chiropractors any radiographs of the subjects that wereless than three years old. The need for additional radiographs wasdetermined by the chiropractor.
The chiropractors had 6 to 14 years of experience, and one had
a master’s degree in exercise physiology. Two had advanced training in chiropractic orthopedics, and one in sports chiropractic.

1022 ·The initial visit was scheduled within four days after randomization, and up to eight additional visits were scheduled, at the discretion of the chiropractor, over the ensuing month. A chiropractor consultant observed the chiropractors at the start and end of
the study and confirmed their compliance with the treatment
protocol.
Educational Booklet

A minimal-intervention control group received an educational
booklet to minimize potential disappointment with not receivinga physical treatment. The booklet discussed causes of back pain,
prognosis, appropriate use of imaging studies and specialists, andactivities for promoting recovery and preventing recurrences. A
previous trial found that the use of this booklet as a supplement
to standard care was not associated with improved outcomes,
even though subjects considered the booklet useful. 23
Outcome Measures
Because back pain often recurs, both short-term outcome (1, 4,
and 12 weeks) and long-term outcome (1 to 2 years) were assessed. The assessment of short-term outcome focused on the effects of the assigned treatment on symptoms, the level of function, and the level of disability; the assessment of long-term
outcomes focused on recurrences of low back pain and the use of
back-related health care. At base line and at all follow-up visits,
subjects rated how “bothersome” back pain, leg pain, and numbness or tingling had been during the preceding 24 hours. An 11point scale was used in which a score of 0 indicated that thesymptoms were “not at all bothersome” and a score of 10 thatthe symptoms were “extremely bothersome.” The score for themost bothersome symptom was used. A similar scale has shown
substantial construct validity.24
A modified 24 Roland Disability Scale 25,26 was used to measure
the patients’ ability to function. The scores on this scale are basedon the answers to 23 yes–no questions about daily activities andcan range from 0 (none of the 23 daily activities limited by backpain) to 23 (all 23 activities limited by back pain). This instrument is reliable, valid, and sensitive, 24,27 and the questions are easily administered by telephone.
Disability was measured with questions from the National HealthInterview Survey about the number of days spent in bed, spenthome from work or school, or with reduced activity. 28 These
questions were modified to refer specifically to back-related restrictions.
The subjects’ use of health care for back-related problems was
identified by a review of encounter forms completed by physicaltherapists and chiropractors, automated data on utilization for
HMO-covered services, and questionnaires on visits not coveredby the HMO. The subjects were asked to rate their care for backpain (excellent, very good, good, fair, or poor) at one and fourweeks.
Assessment of Outcome
Data on outcomes at one and four weeks were collected by
telephone; subsequent outcomes were assessed by mail with telephone follow-up. Interviewers were unaware of the subjects’study assignment; however, after the outcomes had been recorded
at four weeks, subjects indicated which treatment they had been
assigned. Those who had received chiropractic or physical therapy
were asked about their compliance with therapy and the estimated length of their visits.
Costs of Care
The study paid for the costs of the study treatments. Nonstudy
treatments were covered (within contract limitations) by the subjects’ health insurance. The subjects typically had office-visit copayments of $5 to $10 and drug copayments of $5 per onemonth supply of medications. Physical therapy was covered for all
HMO enrollees on a physician’s referral and with a visit copay-

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PHYSICAL THERAPY, CHIROPRAC TIC MANIPUL ATION, OR AN EDUCATIONAL BOOKLET FOR BACK PAIN

ment. About one third of the subjects had coverage for chiropractic services, which did not require a physician’s referral but did
require a copayment. The cost of care was determined from the
HMO’s cost-accounting system and reflects the costs to the HMO.
Thus, out-of-pocket expenses for patients are not included.
Statistical Analysis
The study was designed to have at least 80 percent power todetect a 2.5-point difference in the scores on the Roland Disability Scale and a 1.5-point difference in the scores on the bothersomeness scale for the comparison between physical therapy andchiropractic care. These differences are consistent with those considered minimally important.24
Data were analyzed according to the intention to treat. The
Roland Disability and bothersomeness-of-symptoms scores wereanalyzed as continuous variables by analysis of covariance after
adjustment for base-line values.29 A common set of base-line variables predictive of these scores was included in all analyses of covariance (age, age squared, SF-36 mental health score, SF-36 general health perceptions score, previous physical therapy, andsubjects’ expectations of the likelihood of improvement). Because
the primary outcomes were not normally distributed (i.e., many
subjects had substantial symptoms or dysfunction), we used asquare-root transformation before analysis so that the data better
met the assumptions of the parametric test. 29
Nonparametric tests were used to confirm the results of theparametric analyses. For dichotomous outcomes, logistic regression was used, with adjustment for base-line values wheneveravailable.29 For all comparisons of the three treatment groups a
P value of 0.05 was considered to indicate statistical significance,
and Sidak’s method for pairwise comparisons was used to adjust
for multiple comparisons.30 All P values were two-tailed.

RESULTS
Recruitment and Follow-up of Patients

Of 3800 patients who were potentially eligible forthe study, 714 (19 percent) met the initial inclusion
criteria. The most common reasons for exclusion
were severe concurrent conditions (27 percent), involvement in claims for compensation or litigation
because of the back injury (20 percent), or visits topractitioners other than their primary care physicians (19 percent). A total of 493 patients (69 percent) agreed to participate, and 323 remained eligible one week later. Two subjects were excluded after
randomization (one because of a urinary tract infection and one because of pancreatic cancer). Thus, 66
were assigned to receive the booklet, 122 to chiropractic, and 133 to physical therapy. Between 89 and96 percent of the subjects responded to each of thefollow-up questionnaires.
Base-Line Characteristics

The typical subject was approximately 40 years
old, white, well educated, and employed (Table 1).
The mean scores on the SF-36 general health perceptions subscale were above national norms (77.1
vs. 71.4),31 but the mean scores on the mental
health subscale were below national norms (71.2 vs.
76.5). Most subjects had previously received treatment for back pain, and about one third had previously received physical therapy and one third chiropractic care (some had had both). Most subjects had

had back pain for less than six weeks, and 59 percent
had had back pain for less than three weeks.
There were only a few significant differences inbase-line characteristics among the treatment groups(Table 1): subjects in the chiropractic group wereless likely to have used chiropractic services previously, subjects in the physical-therapy group had
more bothersome symptoms, and subjects in the educational-booklet group reported fewer days withrestricted activity and lower expectations that theircondition would improve in a month’s time.
Study Treatments

Ninety-six percent of the subjects in the chiropractic group and 97 percent of the subjects in thephysical-therapy group visited their assigned provider at least once. The mean number of chiropractic
visits exceeded the mean number of physical-therapy
visits by 50 percent (6.9 vs. 4.6, P<0.001). According to the subjects’ reports, the total amount of timespent with the provider was virtually identical in thetwo groups (about 145 minutes). No important adverse effects of treatment were reported in any of thegroups.
Chiropractic

Chiropractors obtained radiographs for 63 percent of the subjects (58 of 92) who had not undergone radiography at the HMO. The most common
diagnoses were sprain or strain (about 50 percent ofsubjects) and facet syndrome (30 percent). Eightytwo percent of the subjects underwent manipulation
at the initial visit. All subjects underwent manipulation of the lumbar or lumbosacral region (or both).
In addition, 54 percent underwent sacral or sacroiliac manipulation, 27 percent thoracic manipulation,
12 percent cervical manipulation, and 6 percent manipulation of the hip, pelvis, or ischium. Sixty-fourpercent of the subjects underwent manipulation of
more than one level of the spine. Other treatments
included ice packs (20 percent), brief localized massage (49 percent), and exercises in the office (41percent) or at home (58 percent).
Physical Therapy

Ninety-two percent of the subjects were given adiagnosis of “derangement.” At four weeks, 78 percent of the subjects reported that they had performed the recommended exercises on at least fourof the preceding seven days. Most subjects reported
regular use of the lumbar roll (71 percent) and recommended sitting posture (83 percent). Therapists
considered 55 percent of their patients to be complying with recommended exercises.
Cost

All 66 subjects in the booklet group were mailed
a $1 booklet (Table 2). The mean cost of chiropracVol ume 33 9

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TABLE 1. BASE-LINE CHARACTERISTICS OF THE SUBJECTS.*CHARACTERISTICBOOKLETGROUP (N=66)

CHIROPRACTIC
GROUP(N=122)

PHYSICALTHERAPY
GROUP(N=133)ALL SUBJECTSNO. OF
VALUE

Age (yr)
Female sex (%)
Employed or self-employed (%)
Cigarette smoker (%)
General health perceptions score‡
Mental health score‡
History of LBP>2 Prior episodes of LBP (%)
First sought care for LBP in preceding year (%)
Prior physical therapy for LBP (%)
Helpfulness§
Prior chiropractic for LBP (%)
Helpfulness§
Current episode of LBP
Duration <6 wk (%)
Bothersomeness of symptoms in preceding
24 hours¶
Roland Disability score¿»1 Day of bed rest due to LBP in preceding
week (%)»1 Day of work lost due to LBP in preceding
week (%)»1 Day of restricted activity due to LBP inpreceding week (%)
Taking medication for LBP (%)
Taking narcotic analgesics for LBP (%)
Recent LBP care very good to excellent (%)
Expect LBP to be much better in a month’s time (%)

SUBJECTS†

40.1±11.2
4285
1175.7±20.7
69.8±17.4

39.7±9.45391
1777.3±16.5
70.6±15.7

41.8±11.5 40.7±10.7
47
48
89
89
19
17
77.6±16.9 77.1±17.6
72.5±16.6 71.2±16.4

321
321
321
313
313
313

54
40
37
5.1±3.640
6.2±3.1

584031
5.7±3.224
7.2±2.3562932
6.1±2.9357.0±2.456
3633
5.7±3.2
32
6.8±2.6

321
321
310
100
313
92

72
5.3±1.883
5.5±2.177
6.0±2.578
5.7±2.2313
313

11.7±5.42212.1±5.53512.2±5.62412.0±5.5
28

313
313

30

39

41

38

279

52

72

65

65

312

77
8
34
59

82
13
42
79

84
15
50
71

81
13
43
71

313
313
305
305

*Plus–minus values are means ±SD. The following differences among the groups were significant: prior chiropractic
treatment was less likely in the chiropractic group (P=0.04), the mean bothersomeness score was higher in the physicaltherapy group (P=0.04), and the booklet group was less likely to have had »1 day of restricted activity due to back painin the preceding week (P=0.02) and had a lower expectation that back pain would be much better in one month’s time
(P=0.02). The treatment groups were similar with respect to the following variables: 79 percent overall had attended
college, 89 percent were white, 68 percent were married, 39 percent had a family income of more than $50,000 per year,
21 percent had a job requiring lifting more than 9 kg (20 lb) at a time, 57 percent had actively exercised in the preceding
week, 6 percent considered their health fair or poor, 4 percent had ever been hospitalized for a back problem, 60 percent
had read articles about back pain (mean helpfulness of readings on back pain on a scale of 0 to 10, 5.8), 10 percent had
pain that extended below the knee, and 53 percent had had back symptoms during most of the preceding 24 hours. LBP
denotes low back pain.
†The sample sizes for questions on the base-line questionnaire are slightly lower than those for questions on the initialeligibility questionnaire because of the loss of a diskette with base-line data for eight subjects (one in the booklet group,
three in the chiropractic group, and four in the physical-therapy group).
‡Scores can range from 0 to 100, with higher scores indicating better function.
§Scores can range from 0 to 10, with higher scores indicating greater helpfulness.
¶Scores can range from 0 to 10, with higher scores indicating more bothersome symptoms.
¿Scores can range from 0 to 23, with higher scores indicating greater reductions in daily activities.

tic treatment was $226.08 per subject, 18 percent of
which was for radiography. The cost of physical therapy averaged $238.54 per subject, with visits to providers accounting for 93 percent of the cost.
Other Treatments

Eighteen percent of the subjects in the booklet
group visited a health care provider for back pain
during the study month, and only 8 percent of the1024 ·

subjects in the chiropractic group and 9 percent of
those in the physical-therapy group visited providers
other than those assigned. The reported use of exercise was almost identical in the three groups atbase line (about 57 percent) and one month (about
81 percent). During the month, the percentage ofsubjects who used back-pain medication of any typedecreased from 82 percent to 18 percent in the chiropractic group, from 84 percent to 27 percent in

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PHYSICAL THERAPY, CHIROPRAC TIC MANIPUL ATION, OR AN EDUCATIONAL BOOKLET FOR BACK PAIN

TABLE 2. MEAN COSTS OF THE TREATMENTS.*GROUPPERCENT OFSUBJECTS
INCURRINGCOST†

NO. OFUNITSCOSTPER UNIT

TOTAL
COSTS

MEAN
COST PERSUBJECT

dollars

Booklet (n=66)
BookletMean total cost per subject
Chiropractic (n=122)
VisitsPlain films (anteroposterior and lateral)
Mean total cost per subject
Physical therapy (n=133)
Visits
McKenzie book
Lumbar roll
Mean total cost per subject

100

66

1.00

66.00

1.00
1.00

96
63‡

807
74

28.01
67.26

22,604.07
4,977.24

185.2840.80
226.08

97
94
92

589
125
122

49.99
8.50
10.00

29,444.11
1,062.50
1,220.00

221.387.99
9.17
238.54*Costs are in 1995 dollars.
†Four percent of subjects in the chiropractic group and 3 percent of subjects in the physical-therapy
group did not visit their assigned provider at all.
‡Chiropractors ordered radiographs for 58 of the 92 subjects (63 percent) who had not undergone
radiography at the HMO. We assumed that the chiropractors would also have ordered radiographsfor 63 percent of the 25 subjects who had undergone radiography at the HMO.

the physical-therapy group, and from 77 percent to32 percent in the booklet group (P<0.05 for thedifferences among the groups after adjustment forbase-line use). Fewer than 2 percent of the subjects
reported using corsets, braces, traction, transcutaneous electrical nerve stimulation, or injections.
Outcomes

Data on primary outcomes are shown in Table 3.
The bothersomeness of symptoms differed among
the groups at base line (P=0.04) and after 4 weeks(P=0.007) and 12 weeks (P=0.02). After adjustment
for the base-line bothersomeness scores and theprognostic covariates, the differences among groups
remained significant at 4 weeks (P=0.02) but not at
12 weeks (P=0.06) (Fig. 1). Pairwise comparisons
showed that the chiropractic group had less severe
symptoms than the booklet group at four weeks(P=0.02), and there was a trend toward less severe
symptoms in the physical-therapy group (P=0.06).
After square-root transformation to adjust for the
non-normal distribution of the outcome measures,the differences among the treatment groups were nolonger significant at 4 weeks (P=0.14) or 12 weeks(P=0.19).
Differences in the Roland Disability scores among
the groups were small and approached significanceonly at one year (P=0.05), with greater dysfunctionin the booklet group than in the other two groups.
Adjustment for the base-line Roland Disability score
and the other covariates had little effect (Table 3 andFig. 2). There were no significant differences between groups at one year after square-root transfor-

mation (P=0.13) or with the use of the nonparametric test (P=0.16). There were few interactions
between the treatment and the subjects’ characteristics, but in the booklet group, poorer mental healthscores were associated with worse outcomes. There
were no significant differences among the chiropractors or the therapists with respect to their effect on
the subjects’ symptoms (e.g., P=0.71 and P=0.22,
respectively, at four weeks) or function (e.g., P=0.51
and P=0.30, respectively).
The number of days of back-related disability was
similar among the groups. In the 11 months after
treatment, the percentages of subjects reporting reduced activity were similar (36 percent in the booklet group, 33 percent in the chiropractic group, and35 percent in the physical-therapy group; P=0.94)
as were the percentages who reported the need for
bed rest (9 percent, 8 percent, and 11 percent, respectively; P=0.81) and the percentages who reported missing work (17 percent, 7 percent, and 13
percent, respectively; P=0.28). Approximately 50 percent of the subjects in each group reported recurrences at one year, and 70 percent reported recurrences during the second year, but there were no
significant differences among the groups in the percentages who sought care for back pain. For example, during the second year, 24 percent of the subjects in the booklet group reported visits to any
provider for back pain, as compared with 29 percentof the subjects in the chiropractic group and 20 percent of the subjects in the physical-therapy group(P=0.29). Analysis of HMO records yielded similar
results (data not shown).
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TABLE 3. BOTHERSOMENESS OF SYMPTOMS AND ROLAND DISABILITY SCORES AT BASE LINE, 4 WEEKS,
AND 12 WEEKS.*BOOKLETGROUP

VARIABLE

CHIROPRACTICGROUPPHYSICALTHERAPYGROUPP VALUEUNADJUSTED ADJUSTED†

Base line
No. of subjects
Bothersomeness of symptoms— mean (95% CI)
Roland Disability score— mean (95% CI)
4 Weeks
No. of subjects
Bothersomeness of symptoms— mean (95% CI)
Roland Disability score— mean (95% CI)
12 Weeks
No. of subjects
Bothersomeness of symptoms— mean (95% CI)
Roland Disability score— mean (95% CI)

65
5.3 (4.9–5.7)

119
5.5 (5.1–5.8)

129
6.0 (5.6–6.5)

0.04

—

11.7 (10.4–13.0)

12.1 (11.2–13.1)

12.2 (11.2–13.1)

0.83

—

60
3.1 (2.4–3.9)

118
1.9 (1.5–2.2)

129
2.3 (1.9–2.8)

0.007

0.02

4.9 (3.8–6.0)

3.7 (2.9–4.5)

4.1 (3.3–4.9)

0.25

0.28

63
3.2 (2.4–4.0)

118
2.0 (1.6–2.4)

117
2.7 (2.2–3.2)

0.02

0.06

4.3 (3.1–5.5)

3.1 (2.4–3.9)

4.1 (3.2–5.0)

0.15

0.28

*CI denotes confidence interval for unadjusted means. Higher scores indicate more severe symptoms or dysfunction.
†The P values pertain to analyses that were adjusted for the base-line value of the outcome measure and prognostic
variables (age, age squared, SF-36 general health perceptions and mental health scale scores, previous physical therapy,
and patient’s expectation of the likelihood of improvement in one month’s time). Pairwise comparisons adjusted for thesesame variables yielded the following results for the bothersomeness of symptoms: at 4 weeks, chiropractic group vs. booklet group, P=0.02; physical-therapy group vs. booklet group, P=0.06; chiropractic group vs. physical-therapy group,
P=0.93; and at 12 weeks, chiropractic group vs. booklet group, P=0.06; physical-therapy group vs. booklet group,
P=0.37; and chiropractic group vs. physical therapy group, P=0.66. The respective values for the Roland Disability score
were as follows: at 4 weeks, chiropractic group vs. booklet group, P=0.32; physical-therapy group vs. booklet group,
P=0.50; chiropractic group vs. physical-therapy group, P=0.97; and at 12 weeks, chiropractic group vs. booklet group,
P=0.45; physical-therapy group vs. booklet group, P=1.00; and chiropractic group vs. physical-therapy group, P=0.45.
The pairwise comparisons were adjusted to account for multiple comparisons.

Total costs of care to the HMO for low back pain
over a two-year period differed by less than 2 percent in the chiropractic and physical-therapy groups
and were almost three times as high as in the booklet group (Table 4). Although most of the higher
costs in the chiropractic and physical-therapy groups
were attributable to the treatments themselves (Tables 2 and 4), the cost of other HMO services forlow back pain was also lower in the booklet groupthan in the other two groups.
At both one and four weeks, about 75 percent of
the subjects in the physical-therapy and chiropractic
groups rated their care as “very good” to “excellent,” as compared with about 30 percent of thesubjects in the booklet group (P<0.001). However,about one quarter of the subjects in the booklet
group failed to answer this question, possibly because
only 18 percent received care during this period.
DISCUSSION

For patients with low back pain, we found thatphysical therapy and chiropractic manipulation had
similar effects on symptoms, function, satisfaction
with care, disability, recurrences of back pain, andsubsequent visits for back pain. Although chiroprac1026 ·tic treatment involved more visits than physical therapy, the total time spent with either a chiropractor
or a physical therapist was similar (about 2.5 hours)
as was the total cost of the treatments ($226.08 and$238.54, respectively).
Among other rigorous studies comparing chiropractic and physical therapy, a British study concluded that chiropractic was more beneficial,11,12 whereasa Swedish study found no significant differences inoutcomes or costs.14 The British study found thebenefits of chiropractic treatment to be most evident
among patients who had previously been treated bychiropractors, a group presumably favorably inclined
toward chiropractic care. Neither study included a notreatment comparison group. A Dutch study foundthat manual therapy (manipulation and mobilization) and physiotherapy (exercise, massage, and physical-therapy methods) had similar effects and weresuperior to continued treatment by a general practitioner.32
We found that patients who received chiropractic
manipulation or physical therapy had only marginally better outcomes than those who received only an
educational booklet. Because only 18 percent of thesubjects in the booklet group sought additional care

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PHYSICAL THERAPY, CHIROPRAC TIC MANIPUL ATION, OR AN EDUCATIONAL BOOKLET FOR BACK PAIN

10

Bothersomeness Score

98Booklet
Chiropractic
Physical therapy

7
6
5
4
3

P=0.41

2

P=0.06

P=0.02

1

P=0.16

P=0.34

52

104

55J
109J
122

55J
116J
121

0
0

1

4

12

Weeks of Follow-up
NO. OF SUBJECTS
BookletJ
56J
ChiropracticJ 114J
PhysicalJ
127
therapy

60J
118J
129

63J
118J
117

Figure 1. Bothersomeness of Symptoms.
The values are least-squares means, adjusted for the base-line bothersomeness scores and prognostic
variables (age, age squared, SF-36 general health perceptions and mental health scale scores, previous
physical therapy, and subjects’ expectations of the likelihood of improvement). Higher scores indicate
more severe symptoms.

Roland Disability Score

16
14

Booklet
Chiropractic
Physical therapy

12
10
8
6

P=0.744
P=0.282

P=0.28P=0.06

P=0.11

12

52

104

0
0

1

4

Weeks of Follow-up
Figure 2. Roland Disability Scores.
The values are least-squares means, adjusted for the base-line Roland Disability scores and prognostic
variables (age, age squared, SF-36 general health perceptions and mental health scale scores, previous
physical therapy, and subjects’ expectations of the likelihood of improvement). Higher scores indicate
greater disability. The numbers of subjects are the same as in Figure 1.

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·

1027

The Ne w E n g l a nd Jo u r n a l o f Me d ic i ne

TABLE 4. MEAN COSTS OF CARE FOR LOW BACK PAIN
OVER A TWO-YEAR PERIOD.

BOOKLET
GROUP(N=66)TYPE OF COST

PHYSICALCHIROPRACTIC THERAPY
GROUP
GROUP
(N=133)(N=122)
dollars

Study treatments and supplies (mo 1)
HMO services for low back pain*
First year
Second year
Total costs

1

226

239

87
65
153

114
89
429

134
64
437

*These costs include the costs to the HMO for office visits, radiology,
laboratory tests, and medications but exclude the costs of the study treatments. Patients’ copayments are not included. There were no hospitalizations or operations for back problems in the two-year period. The mean
number of months of continued enrollment in the HMO was similar in thethree groups over the 24-month period (range, 20.8 to 21.5 months).

during the month after randomization, this groupwas similar in some respects to a no-treatment control group. Although some outcomes for the chiropractic and physical-therapy groups were superior tothose for the booklet group, the differences were
small and, after adjustment, were significant only forthe bothersomeness of symptoms at four weeks andthe subjects’ satisfaction with care at one and fourweeks. None of the observed differences in symptoms or function exceeded the predefined criteria
for clinical importance — that is, a 2.5-point difference in the scores on the Roland Disability Scale ora 1.5-point difference in the scores on the bothersomeness scale. The difference in the bothersomeness of symptoms was not significant after datatransformation to compensate for the skewed distribution of scores. Thus, although chiropractic manipulation and physical therapy may slightly reduce
symptoms, their main benefit for patients with low
back pain appears to be increased satisfaction withcare. Because only a small fraction of subjects in thebooklet group received care during follow-up, their
responses to questions about satisfaction with careare difficult to interpret.
The marginally better outcome of the physicaltreatments raises the possibility that effects werenonspecific. Although nearly all subjects in the physical-therapy and chiropractic groups had repeatedcontact with providers, most subjects in the booklet
group had none. Patients may find such contact satisfying and this may affect their perceptions of symptoms. A positive association between the number oftreatments (contact with providers) and improvement of back-related symptoms has been reported.33
We found no significant differences among thegroups in recurrences of back pain or in the use of1028 ·

services during follow-up. This casts doubt on theability of the self-care–oriented McKenzie physicaltherapy to reduce the utilization of services. The overall costs of care for back pain were lowest in thebooklet group, so there was no evidence that thehigher initial costs of the physical treatments wereoffset by later savings.
The relative costs of chiropractic and McKenzie
treatments could differ in other settings. The number of visits was left to the discretion of providers(who were aware that both costs and benefits would
be measured), and the smaller number of visits to
McKenzie therapists (HMO employees) than to chiropractors (in private practice) may reflect differences in practice styles.15
The generalizability of this study is limited by theuse of a single health care system, the use of specificforms of chiropractic and physical therapy, the useof one month of therapy, and the exclusion of patients with sciatica. The chiropractic manipulativetechnique was chosen because it was well understood and widely practiced. The extent to which
McKenzie therapy in this study resembled that provided elsewhere is less clear. The McKenzie therapists received special training and were among asmall number worldwide who had passed a certification examination. Thus, it seems unlikely that the effectiveness of McKenzie therapists would be greaterin other settings.
Whether the small benefits of these treatments areworth their additional costs is open to question.
Given the limited benefits and high costs, it seems
unwise to refer all patients with low back pain forchiropractic or McKenzie therapy. Ideally, there would
be some way of identifying the subgroups that are
most likely to benefit from one or both of these
therapies, though we were unable to identify any
predictive characteristics. In any event, these results
and those of another recent study14 suggest that for
low back pain, there are no clear advantages of chiropractic manipulation — in terms of either effectiveness or cost — over physical therapy.
Supported by a grant (HS07915) from the Agency for Health Care Policy and Research.

We are indebted to the many people who contributed to the successful completion of this study, in particular our project team (Jenny
Achilles, Dennis Bejin, Russ Bradley, Carol Canfield, Kristin Delaney, Dakota Duncan, Ben Givens, Stephanie Hauge, Kay Hooks,
Marcia Hunt, Nancy Monroe, Sarah Parkhurst, Katie Saunders,Jane Steetle, and Kim Wheeler), our consultants (Willard Manning, Kathy Hoyt, and Kelli Pearson), the participating chiropractors, the heads of the Group Health Northgate and Eastside physicaltherapy departments (Nancy Casey, Macy Massey, and Joel Suelzle),
the participating physical therapists (Ann Barry, Rick Bocko, Nancy
Casey, Hillary Haug, Cathie Hobbs, Leona Hokanson, Renee Joergens, Bonnie Kane, Sheila Markman, Macy Massey, Eileen Schrode,
Meta Thayer, and Carol Worley), Robin McKenzie and the McKenzie
Institute faculty, and our Agency for Health Care Policy and Research project officer, Mary Cummings.

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PHYSICAL THERAPY, CHIROPRAC TIC MANIPUL ATION, OR AN EDUCATIONAL BOOKLET FOR BACK PAIN

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·1029