abnormality that is associated with unexplained infertility and which is not due to low concentrations ofcirculating progesterone.
This work was funded by a grant from Birthright.
lTetnpleton AA, Penney GJC. The incidence, characteristics, and prognosis ofpatients whose infertility is unexplained. Fertil Steril 1982;37: 175-82.
2 Aplin JD, Seif MIW. A monoclonal antibody to a cell surface determittant in
human endometrial epithelium: stage-specific expression in the menstrual
cycle. Amj Obstet Gvnecol 1987;156:250-3.
3 Seif IMW, Aplin JD, Foden LJ, Tindall 'VR. A novel approach for monitoring
the endometrial cycle and detecting ovulation. Am J Obstet Gynecol
1989;160:357-62.
4 Smith RA, Seif MIW, Rogers AW, et al. The endometrial cycle: the expressionof a secretory component correlated with the luteinising hormone peak.
Hum Reprod 1989;4:236-42.
5 Aplin JD, Hoadley MNIE, Seif MW. Hormonally regulated secretion of keratan
sulphate by human endometrial epithelium. Biochem Soc Trans 1989;17:
136-7.
6 Hoadlev ME, Aplin JD, Seif MlW. Menstrual cycle-dependent expression of
keratan sulphate in lIuman endoinetrium. Blochem_7 1990;266:757-63.

7 Seif MW, Aplin JD, Buckles CH. Luteal phase defect: the possibility of an
immunohistochemical diagnosis. Fertil Steril 1989;51:273-9.
8 Seif MW, Aplin JD, Awad H, Wells D. The effect of the intrauterine
contraceptive device on endometrial secretory function: a possible mode ofaction. Contraception 1989;40:81-9.
9 Dockery P, Li TC, Rogers AW, Cooke ID, Lenton EA, Warren MA. An
examination of the variation in timed endometrial biopsies. Hum Reprod
1988;3:715-20.
Li
10 TC, Rogers AW, Lenton EA, Dockery P, Cooke ID. A comparison between
two methods of chronological dating of human endometrial biopsies during
the luteal phase, and their correlation with histologic dating. Fertil Stertl
1987;48:928-32.
11 Belsey MA, Eliasson R, Gallegos AJ, Moghissi KS, Paulsen CA, Prased MRN.
Laboratory manual for the examination of semen andemen-cervical mucus
interaction. Singapore: Press Concern, 1980.
12 Lenton EA, Gelsthorpe CH, Harper R. Measurement of progesterone insaliva: assessment of the normal, fertile range using spontaneous conception
cycles. Clin Endocrinol 1988;28:637-46.
13 Rogers AW. The microscopy and photography of autoradiographs. In Rogers
AW, ed. Techniques of autoradiography. 3rd ed. Amsterdam: Elsevier,
1979:148-64.
14 Li TC, Lenton EA, Dockery P, Rogers AW, Cooke ID. The relation between
daily salivary progesterone profile and endometrial development in the luteal
phase of fertile and infertile women. Br]e Obstet Gynaecol 1989;96:445-53.

(Accepted 30 March 1990)

Low back pain of mechanical origin: randomised comparison ofchiropractic and hospital outpatient treatment
T W Meade, Sandra Dyer, Wendy Browne, Joy Townsend, A 0 Frank
Abstract
Objective-To compare chiropractic and hospital
outpatient treatment for managing low back pain of
mechanical origin.
Design-Randomised controlled trial. Allocation
to chiropractic or hospital management by minimisation to establish groups for analysis of results
according to initial referral clinic, length of current
episode, history, and severity of back pain. Patientswere followed up for up to two years.
Setting-Chiropractic and hospital outpatient
clinics in 11 centres.
Patients-741 Patients aged 18-65 who had nocontraindications to manipulation and who had notbeen treated within the past month.
Interventions-Treatment at the discretion of thechiropractors, who used chiropractic manipulationin most patients, or of the hospital staff, who mostcommonly used Maitland mobilisation or manipulation, or both.
Main outcome measures-Changes in the score on
the Oswestry pain disability questionnaire and in the
results of tests of straight leg raising and lumbar
flexion.
Results-Chiropractic treatment was more effecMRC Epidemiology andMedical Care Unit,
tive than hospital outpatient management, mainly for
Northwick Park Hospital,patients with chronic or severe back pain. A benefit
Harrow, Middlesex HAIof about 7% points on the Oswestry scale was seen at
3UJ
twoyears. The benefit of chiropractic treatment
T W Meade, FRCP, director
became more evident throughout the follow up
Sandra Dyer, MSC, scientificperiod. Secondary outcome measures also showed
staffthat chiropractic was more beneficial.
Wendy Browne, RGN,
Conclusions-For patients with low back pain in
nursing stafJ
Joy Townsend, MSC, scientific whom manipulation is not contraindicated chirostaff
practic almost certainly confers worthwhile, longterm benefit in comparison with hospital outpatient
Northwick Park Hospital,
management. The benefit is seen mainly in those
Harrow, Middlesex HAI
withchronic or severe pain. Introducing chiropractic
3UJ
A 0 Frank, MRCP, consultant into NHS practice should be considered.
in rheumatology andrehabilitation
Introduction
Correspondence to: Dr
The high incidence of back pain, its chronic and
Meade.
recurrent nature in many patients, and its contribution
as a main cause of absence from work are well known.
No general consensus exists about the most effective
Brfecdj 1990;300:1431-7
BMJ

VOLUME 300

2 JUNE 1990

treatment. Largely anecdotally, patients and therapists
often claim great improvements after manipulative
treatment by alternative practitioners, including
chiropractors. A recent report from the board ofscience and education of the BMA considered thatmanipulative treatment ofback pain by lay practitioners
may provide "a safe and helpful service,"' thus
strengthening the Cochrane committee's recommendation that randomised trials of treatment forback pain should include an evaluation of heterodox
methods.
A comparison of chiropractic with conventional
hospital outpatient management of low back pain
could take one of two main forms. Firstly, it could be
a "pragmatic" trial, which would test what happens in
day to day practice and in which details of the type,
frequency, and duration of treatment would be at thediscretion of the chiropractor or hospital team.' The
disadvantage of a pragmatic trial is that if a clear
difference is found between the treatments it may not
be possible to identify the components of the more
successful treatment that were responsible. Secondly,
it could be a "fastidious" trial, which would compare
chiropractic manipulation with a particular form of
non-manipulative physiotherapy.' Though this type oftrial may be more likely to identify specific componentsof treatment that are effective, there would be a highchance of not including the effective components
because of the many techniques used to treat backpain.4 In addition, its results might have only limited
applicability.
We adopted a pragmatic approach for two main
reasons: firstly, because of the probable difficulty of
securing agreement about standard forms of treatment,
particularly in hospital, and consequently the small
number of patients who could be recruited into afastidious trial and, secondly, because the effectivenessof treatment in day to day practice, whether chiropractic
or in hospital, is of most immediate interest to patients
as well as doctors and therapists.

Patients and methods
CENTRES AND CLINICS

The study was based on the methods of a feasibility
study.4 Each centre consisted of a chiropractic clinic
1431

and a hospital clinic. After the feasibility studv had
been completed 11 centres with hospital and chiropractic clinics within a reasonable distance of one
another agreed to take part in this trial.

PATIENTS

The main criterion for eligibility was that patientsshould have no contraindication to manipulation as
almost all the patients treated by chiropractic would
receive manipulation and it was important to avoid
TABLE I-Reasons for ineligibility for or exc lusion from tnal in patients with back pain presenting to damage by manipulation. Thus patients were excluded
or
in
two
are
numbers
hospital chiropractor
centres. Figures(percentages)
if there was evidence that a nerve root was affected,
though restricted straight leg raising on its own was not
Initiallv attended:a reason for exclusion; major structural abnormalities
Hospital (n = 75 1'
Chiropractor (n= 543)
were visible on radiography; or osteopenia or an
infectious cause was suspected and for various other
Ineigibilitv:
Outside age range
67 (9)
17(3)reasons,
including social conditions and pending liti124 (23)168 (22)
Nerve root affectedgation. Only patients aged 18 to 65 who had not been
24 (4)
22 (3)
Spinal abnormalitV
52 (10)Recent treatment
53 (7!
treated within the past month and who had not
99 (13)
Free of pain
6 1)
the same referral clinic within the past two
attended
81 15)
207 (28)
Other*
years were recruited.
304 (56)616 (82)
Total
Two of the 11 centres kept a record of all patients
presenting with back pain. Table I summarises the
Exclusion:62 (11)
16 (2!
Unwilling, no time
reasons for ineligibility or exclusion in these two
87 (16)
W'anted chiropractic treatment
centres, confirming the general finding of the feasibility
9 1)
Wanted hospital treatment
23 (4)tOther
2(003)
study in one of the other centres that contraindications
were commoner among patients presenting initially to
172 (32)Total
27 (4?
hospital while considerations of convenience-for*Includes other diseases, psychosocial difficulties, pcevious surgery, and litigation pending.
example, to avoid waiting and delay in starting treattIncludes previously unsuccessful treatment in hospital.
ment-were commoner among patients initiallypresenting to the chiropractors. Among 135 eligible
I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
patients referred to hospital 108 (80%) entered thetrial, compared with 67 of 239 (28%) referred tochiropractors. In all, 175 (47%) of those eligible
in these two centres entered. Figure 1 summarises therecruitment, investigation, treatment, and follow up
procedures in eligible patients.
All patients underwent radiography of the lumbar
spine, the x ray films (whether taken by the chiropractor
Patient may
or in hospital) being reported on by a hospital radibe ineligible
ologist. Permission was then sought from generalor unwilling
practitioners for each patient's participation in order toto participate
comply with the General Medical Council's advisory
guidelines about collaboration with heterodox practitioners. Two general practitioners in one centre said
that they did not want any of their patients included.
Permission was also withheld for five patients under
Patient mayother general practitioners. The General Medical
be found toCouncil also advised that the medically qualified
be ineligible
members of the hospital teams should satisfy themselves about the competence of the chiropractors. Thiswas done through discussions during the early stages of
the trial.
The purpose of the trial was explained to eligible
patients by the nurse coordinator in each centre, whopointed out that participation would mean an equalchance of being treated by chiropractic or conventional
hospital methods, the decision being made at random.
Patients were also given a written explanation and toldthat if they were allocated for treatment at the clinic
they had not originally attended they would be free atany stage to return to the original clinic. All patientssigned a consent form, and the study was approved by
the ethical committees of the 11 centres.
The fees of patients receiving chiropractic treatment
were paid by grants from funding agencies regardlessof whether these patients had originally attended
chiropractic or hospital clinics. The number of patients
recruited in each centre ranged from 14 to 198.
General practitioners in three centres had directaccess to physiotherapy departments for all or part of
the trial, accounting for the higher proportion ofpatients with short episodes of pain compared with thatin the feasibility study.'
I

OUTCOMEFIG 1 -Recruitment and follow up procedures

1432

The patients' progress was measured with theOswestry back pain questionnaire," which gives scoresfor 10 sections-for example, intensity of pain, difficulty with lifting, walking, and travelling. The result is
BMJ

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2 JUNE 1990

expressed on a scale ranging from 0% (no pain or
difficulties) to 100% (highest score for pain or difficultyon all items). Each patient completed the questionnaire
at recruitment and shortly before starting treatment.
Further questionnaires were then sent by post withprepaid reply envelopes at weekly intervals for six
weeks, at six months, and at one and two years after
entry. Subsidiary measures of outcome included
assessing straight leg raising with a goniometer andlumbar flexion'; both were measured at entry and at six
weeks by the coordinating nurse, the readings made atentry being unavailable to her at the six week follow up
appointment. The results reported here include theresponses to follow up questionnaires and othermeasures completed by the end of September 1989,
when all patients had been followed up for six months,
fewer patients having completed one and two year
follow up questionnaires.
At entry patients also completed psychologicalquestionnaires dealing with depressive symptoms,
somatic awareness, and inappropriate symptoms.9
TREATMENT

Each patient's treatment was at the discretion of thechiropractor or hospital team. Based on the pattern ofchiropractic treatments in the feasibility study andin discussion with a representative of the British
Chiropractic Association the chiropractors wereallowed to give a maximum of 10 treatments, whichwere intended to be concentrated within the first threemonths but could be spread over a year if considerednecessary.
STATISTICS

We recruited as many patients as the available
funding allowed. We estimated from the feasibility
study that about 2000 patients would be needed todetect a difference between the two approaches of 2%
points on the Oswestry scale (at the 5% level, with 90%
power)-for example, a decrease in Oswestry scorefrom 30% to 25% in one group compared with adecrease from 30% to 23% in the other-and thatdifferences of 2-5%, 3 0%, 4 0% and 5 0% points
would require about 1200, 850, 500, and 300 patients
respectively. Table II gives examples ofthe implicationsof a range of differences in mean Oswestry scores.
Patients were randomly allocated to treatment, andthe method of minimisation'° was used within eachcentre to establish groups for analysis of results
according to initial referral clinic, length of current
episode (more or less than a month), presence or
TABLE II-Examples of interpretation of differences o?r changes in
Oswestry scores*
Difference %pointsNo pain compared with mild pain; orModerate pain compared with fairly severe pain; orAble to lift only light weights compared with not able to02%
lift anything; orAble to sit for one hour compared with only half an hour
No pain compared with moderate pain; orModerate pain compared with very severe pain; orI
Able to lift light to medium weights compared with unable
to lift anything; orAble to sit for up to one hour compared with lessthan 10 minutes
M1ild pain, ability to lift heavy weights without extra pain,
and ability to sit for up to one hour compared withmoderate pain, ability to lift heavy weights only if
conveniently positioned, and unable to sit for more thanhalf an hour6%
Mild pain, ability to lift light to medium weights, andabilitv to sit for up to one hour compared with fairly severe
pain, unable to lift anything, and able to sit for up to half
an hour
10%

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2 JUNE 1990

TABLE ItI-Characteristics of patients according to randomised treatment group. Figures are numbers (percentages) unless otherwise statedHospital group Chiropractic(n= 357)
group (n:= 384)
Mean (SD) age (years)
Men
Women
Social class*:
I and IIIII
IV and V
Armed forces
Self employed
Initially attended:
Hospital clinic
Chiropractic clinic
Back pain:
With history
With current episode > I monthWith Oswestry score >40%
Previously treated (any method)
Previously using drugst
Mean Oswestry score at recruitment(SD)
Mean pretreatment Oswestry score(SD)

38 5 (10-8)190 (53)
167 (47)

38 9 (11-2)
190 (49)
194 (51)

113 (34)
163 (49)
52 (16)6 (2)47 (13)123 (34)
180 (50)50 (14)7 (2)42 (11)194 (54)
163 (46)

189 (49)
195 (51)271 (76)214 (60)
70 (20)296 (83)
192 (54)288 (75)
226 (59)
78 (20)326 (85)
212 (55)

30 1(13 8)

30 6(13-7)

28-5(14-1)

29-8(14 2)*Details not known in 47 patients.
tMainly analgesics and anti-inflammatory drugs.

The negative sign for changes in Oswestry scores infigures 2 and 3 means a fall -that is an improvement inthese scores (between pretreatment and follow up)reflecting the well known tendency for back pain to
improve spontaneously as well as any treatment effects.
(Similar figures for results according to referral clinic,
length of current episode, and past history are available
on request.)

510
0-5-10CD-15C
0. -20-25,
-3
CI)
U1)
-35

._

c

5-

* *Hospital*Chiropractic

b

0)

0-

~ca

-5-10C-152-20-25-30-35-~~~~co*Scores for sections on lifting, sitting, and pain intensity account formost of the total Oswestry scores. The examples assume no differences inother items.

BMJ

absence of a history of back pain, and an Oswestry
score at entry of >40% or -40%. The feasibility study
had shown that the length of the current episode, inparticular, clearly distinguished two groups of patients,
those with a short current episode improving much
more rapidly (regardless of treatment) than those withlonger episodes.
The interval between recruitment and the start oftreatment varied slightly among the four referral andtreatment clinic groups. To allow for any changes
before the start of treatment the results were based onchanges in Oswestry scores, and this also allowed forthe small differences in pretreatment scores between
the hospital and chiropractic groups (see table III).

I

.

*

0

6

12

-

-

-

-

-

-

-

-

Ir

0

24

Time since start of treatment (months)
FIG 2 -Mean changes in Oswestry scores: a =for all patients, b =forall patients who had been followed up for two years

1433

treatment compared with 29% of patients treatedby chiropractic. Almost all patients had completed
treatment by 12 weeks in the hospital group and by 30
0weeks in the chiropractic group (97%). The chiro-5practors generally treated all patients over a similar_-10period whereas the hospital therapists treated patients-15with long episodes of back pain who were never free of
symptoms for longer periods than those with short-200episodes.
-25Of the 741 patients who started treatment, 29"/I -300
changed their treatment centre (22 within the first six
weeks). Sixty patients did not complete their course ofv o* Hospital0) -35treatment and 77 did not attend for six week follow up
Chiropractic
5(0withthe nurse coordinator. Altogether 608 completedC.)
cl)09the trial to six weeks without missing any treatments orCCD
the six week questionnaire, changing treatment centre,
U3)
ormissing follow up appointments.
-10Table V gives the differences in the changes in-15Oswestry scores between the two treatment groups.
:20.0 Figure 2a, which is based on all data for all patients,-25shows that the change for those treated by chiropractic
was consistently greater than that for those treated in-304 hospital. At two years the patients treated by chiro-35-I
practic had improved by 7% more than those treated in
24 hospital (p=0-01). When the analysis was confined to1206patients all ofwhom had been followed up for two years
Time since start of treatment (months)
FIG 3-Mean changes in Oswestry score: a=for all patients zwith and who had complete data at six weeks, six months,
recruitment score -40% points, b=for all patients with recruitnnent one year, and two years the general pattern was similarscore >40% points(fig 2b) but the differences at six months and a year
were greater. Among patients who originally attended
hospital there was no difference between chiropractic
The results were analysed by intention to tireat andhospital treatment until two years after entry,tr(subject to availability of data on follow up and at enetiY
when
the patients treated by the chiropractors hadfor individual patients). Differences between the ml,eanmore than those treated in hospital (table V).
uimnproved
changes in the two groups were tested by unpairezdFor
who originally attended a chiropractor thepatients
ant
tests. x2 Tests were used to detect any significtreatment was more effective throughout
chiropracticfordifferences between the two treatment groupsthefollowup
period. When the results were confinedexample, in the proportion of patients off wc srkn topatients with complete follow up data for two years,
Missing data account for slightly differing number
however, the patients in both referral groups who were
the text and tables.
treated by chiropractic tended to show greater improvement throughout the follow up.
The results were also analysed according to length ofResults
thecurrent episode of pain. In both groups those
rch
March
to
Ma
1986
Patients were recruited during
treatedby chiropractors improved more than those11
1989. In all, 781 patients were recruited from thetreatedin hospital, the benefit possibly being seen
as
24
from
hospitparticipating centres. Of these, (13earlier in those with a long current episodebesomewhatand 11 from chiropractic clinics) were later found tc(tableThere was no difference between the twoV).
thewithdrew
from
and
16
ineligible(eight, eight)
treatmentsin those with no history of back pain, but
study almost immediately so that 741 started treatmlent
treatment was more effective than hospitalchiropractic
nt)
and
357
treatmei
hospitalchiropractic(384 receiving
treatmentinthose with a history. Figure 3 shows that
Table III summarises the characteristics of the patie nts
those with Oswestry scores >40% at entry responded
in the two treatment groups.
Follow up Oswestry questionnaires were returined better to chiropractic treatment (by 13% at two years)
than those with scores -40%.
by 90% patients at six weeks, by 84% at six mon
follow up at one and two years 17% (18/107)(86% treated by chiropractors, 81% in hospital), by of Between
those initially treated by chiropractors had further
79% at a year (83% chiropractors, 74% hospital) ancl b
72% at two years (76% chiropractors, 69% hospittal). chiropractic treatment and 24% (22/92) of those initially
Because non-response was more common am ,ong treated in hospital had further hospital treatment.
patients treated in hospital than by chiropractors andrandomisation had by chance resulted in a few miore TABLE Iv-Numbers (percentages) of patients receiving specified
patients being allocated to chiropractors (see abc)ve) treatments* and mean numbers of treatment sessions
there were usually more patients treated by chiroTreated bypractors than in hospitals in the analyses. There Mvere
Treated inchiropractor
no obvious systematic differences in the characteris;tics(n =378)
hospital (n= 339)
of non-responders treated by chiropractors or 'in
Maitland mobilisation or manipulation,
hospital.
6 (2)243 (72)
or bothTable IV summarises the treatments received in the Cyriax
42 (12)manipulation
375 (99)
chiropractic and hospital clinics. Not all hospitals Ihad Chiropractic manipulation
8 (2)
86 (25)access to hydrotherapy, but otherwise there were no Traction
8 (2)13Corset(4)
33 (9)
appreciable differences in treatment patterns am ong Exercises
102 (30)of treatment visits:
hospitals. Virtually all the patients treated by ch iro- NoIn(SD)6-9 (2-1)
5-6 (3-7)
six weekst
practors received chiropractic manipulation suchi as
9-1 (3-6)
6-3 (4-8)
Totaltat:)mehigh velocity, low amplitude manipulation sc
in hospital, received more than one
stage. Patients treated by chiropractors received ab)out *Many patients, especially those treatedwere
incomplete. Other treatments
type of treatment. Data on 24 patients
44% more treatments than those treated in hospital .At notshown above included short wave diathermy and hydrotherapy.
six weeks 79% of hospital patients had comple-ted
tp<0o000l.

._

4-

4-

frk

1434

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VOLUME 300

2 JUNE 1990

TABLE IV-Differences (95% confidence intervals) in changes in Oswestry score (mean score hospital group minus mean score for chiropractic
group)t

Allpatients

All patients with results at two years
Hospital referrals:
All results
With results at two years
Chiropractic referrals:
All results

With results at two years
Duration of current episode:l month>I1month
History:Yes
No

Six weeks

Six months

One year

Two years

1-69(-0-74to4-12)
H=309, C=357
2-92 (-2-27 to 8-1 1)
H=83, C=97

3 31*(0-51 to6-11)

7-89** (2-35 to 13 42)
H=83, C=97

2 09(- 113to 531)
H=207, C=247
6.59** (1 79 to 11 40)
H=83, C=97

7-16**(1 86to 12 45)
H=90, C= 104
7-45** (2-08 to 12-82)
H=83, C=97

-0-25 (-3-68 to 3 19)
H= 172,C= 168-0-49 (-6-97 to 5 99)
H=52, C=51

-0-32 (-4 41 to 3 78)
H= 149,C= 154
3-95 (-304 to 10 93)
H=52, C=51

-0-94 (-5-88 to 3-99)
H= 110,C=110
4-84 (-1-69 to 11 37)
H=52, C=51

5-74(-1 12 to 12-61)
H=56,C=54
5-98 (- 108 to 13 05)
H=52, C=S1

3-37* (0-01 to 6 73)
H= 137,C= 189
6-49 (- 1-94 to 14 92)
H=31, C=46

6.75*** (2-92 to 10 58)
H= 133,C= 171
12 35** (2-75 to 21 94)
H=31, C=46

4-87** (0-80 to 8-94)
H=97,C= 137
8-17* (0-85 to 15 48)
H=31, C=46

7-82 (-0 62 to 16 27)
H=34,C=50
8-71* (0 15 to 17 27)
H=31, C=46

0-09(- 3-98to4-15)
H= 126,C= 150
2 61 (-0 10 to 5 33)
H= 183,C=207

4-32(-0 31 to8-95)
H= 116,C= 138
2-35 (-0 86 to 5-56)
H= 166,C= 187

2-21 (-3-06to7-48)
H=86,C=97
2-39 (-1 41 to 6 19)
H= 121,C= 150

9-32*(0-07to 18 56)
H=39,C=40
6-60* (0-76 to 12 44)
H= 51,C=64

2-04 (-0-80 to 4-88)
H=242, C=270
0 51( -4 13 to 5-14)

H=67, C=87

3-11 (-0-15 to 6-37)
H=220, C=245
4 04 ( l- 37 to 9-46)
H=62, C=80

2-99 (-0 83 to 6 80)
H= 162, C= 184- 0-99 (- 6 88 to 4 91)
H=45, C=63

8-31** (2-24 to 14 38)
H=75, C=73
1l42( -10-12 to 12-95)
H= 15, =31

1*73 (-0-28 to 3-74)
H=251, C=284-0 14 (- 7-35 to 7 07)
H=58, C=73

2-39* (0-05 to 4 73)
H=226, C=256
5-59 (-2*79 to 13 97)
H=56, C=69

1-76 (- 1l13 to 4-65)
H= 163, C= 194
3-15 (-5-57 to 11 86)
H=44, C=53

3 19 (- 1*52 to 7 90)

H=282, C=325

Oswestry score at entry:

<40%
>40%

*p<0-05, **p-o.0l, ***p-OOl.

tH =Number of patients in hospital group. C =number of patients in chiropractic group.

TABLE VI -Mean change at six weeks (number ofpatients) for straight leg raising and lumbar flexion, andpercentages ofpatients recording other events according to treatment group
hospital

Treated by Difference between two groups(95% confidence interval)
chiropractor

5-0 (291)
5 3 (288)
0-62 (302)

7-1 (325)
5 8 (323)
0-85 (344)

2-1 (00 to 4 1)*
0-5 (-1 6 to 2-6)
0-23 (-0 04 to 0 50)

81 (253/311)
77 (245/317)
41 (38/92)

91 (329/361)
87 (312/360)
36 (39/107)

9-7 (4-5 to 14-9)**
9-4 (3-6 to 15-2)**-4-9 ( -18-5 to 8-7)

35 (99/285)
29 (62/212)
36(33/92)

33 (109/331)
30 (75/251)

30(32/107)-1-8 (-9-3 to 57)
0-7 (-7-6 to 9-0)
-6-0(-191 to7-1)

59 (81/137)
25 (33/131)
37 (73/198)
Experiencing pain daily
Oswestry score as high as or higher than before treatment:

64 (112/176)
24 (42/172)
31 (71/232)

4-5 (-6-4 to 15-4)-0-8 (-10-6 to 9-0)
-6-3 (-15 3 to 2-7)

26(72/274)
34 (67/195)
45 (37/83)

17(53/321)
24 (57/238)
28 (27/97)-9-8(-16 4to- 3.2)**-10-5 (-191 to -1-9)*- 16-8 (- 30 7 to - 2.9)*

Treated in

Straight leg raising (°):
Right leg
Left leg
Lumbar flexion (cm)Treatment at 6 weeks:
Satisfied or very satisfied
Partially or complete relieved
Any further treatment between 1 and 2 years
Using drugs :At 6 months
At l year
At2years
Pain at 1 year:
Pain free for "several months"
Further equally severe episodeAt6months
Up to I year
Up to 2 years*p<0c05, **p<0005.

tlncluding treatment in generalpractice.

:Mainly analgesics andanti-inflammatory drugs.

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VOLUME 300

Thus the tendency for the changes in the Oswestry
score to remain in favour of chiropractic during thesecond year was probably not due to a disproportionate
reinforcement from further chiropractic treatment
during this period.
In only one centre was hospital treatment possibly
more effective than chiropractic, by 3% and 1% on theOswestry scale at six months and two years respectively.
This centre recruited many patients, mostly throughopen access arrangements, and omitting its results
increased the apparent effectiveness of chiropractic
treatment in the 10 other centres. Two centres showed
little if any difference between chiropractic and hospitaltreatment, and in eight chiropractic was more effective.
No clear relation was found between the number oftreatments and extent of improvement for either
chiropractic or hospital treatment.
Table VI shows that the change in straight leg raisingand lumbar flexion was greater in those treated bychiropractic than those treated in hospital and that fornearly all other subsidiary measures patients treated bychiropractors did better than those treated in hospital.
The smaller proportions of patients treated in hospitalthan by chiropractic who were satisfied with theirtreatment or relieved by it may well account for the
somewhat greater loss to follow up in the hospitalgroup. Because treatment for those allocated to chiro2 JUNE 1990

H=71, C=74
13 13* (0-24 to 26 01)
H= 19, C=30

practic lasted longer than that for those allocated tohospital effects on time off work during the first year
were difficult to assess. Between one and two years thefrequency and duration of absence from work were lessin those treated by chiropractic. Of those with jobs,
21% (18/84) of patients given chiropractic had time offwork because of back pain compared with 35% (26/74)
of hospital patients (p=0O055).
ECONOMIC IMPLICATIONS

The potential economic, resource, and policy
implications of our results are extensive. The average
cost of chiropractic investigation and treatment at
1988-9 prices was £165 per patient compared with £111
for hospital treatment. Some 300 000 patients arereferred to hospital for back pain each year," of whomabout 72000 would be expected to have no contraindications to manipulation.'2 If all these patients werereferred for chiropractic instead of hospital treatment
the annual cost would be about £4m. Our results
suggest that there might be a reduction of some 290 000
days in sickness absence during two years, saving
about £13m in output and £2-9m in social security
payments. As it was not clear, however, that the
improvement in those treated by chiropractic wasrelated to the number of treatments the cost of essential
chiropractic treatment might be substantially less than
£4m. The possibility that patients treated in hospitalwould need more treatment during the second year
than those treated by chiropractic (see above and tableVI) also has to be borne in mind. There is, therefore,
economic support for use of chiropractic in low backpain, though the obvious clinical improvement in painand disability attributable to chiropractic treatment isin itself an adequate reason for considering the use of
chiropractic.

Discussion
Though many randomised controlled trials of treatments for back pain have been carried out, there haveso far been no clear indications in favour of any
particular method. The place of manipulation in backpain has been reviewed by Jayson," who concluded
that any minor benefits seemed to be confined to thosewith acute pain of recent onset, that there was noevidence that manipulation helped those with severe or
chronic back problems, and that it did not reduce long1435

term complications or prevent recurrences. For
chiropractic our findings suggest otherwise. The
difficulties of clinical trials in low back pain have been
discussed.'4 Our trial had the combined advantages ofconsiderably larger numbers and a longer follow up
period than other trials comparing orthodox treatments
or, less often, orthodox and alternative treatments.
We studied only patients who had no contraindications to manipulation. Although this group represents
a substantial proportion of all patients with back pain,
the findings cannot be automatically applied to all
patients with back pain. With this proviso the results
leave little doubt that chiropractic is more effective
than conventional hospital outpatient treatment. The
confidence intervals for the differences in Oswestry
scores were wide, but the degree of improvement
recorded for many of the secondary outcome measures(table VI) suggests that chiropractic has appreciable
benefit. The effects of chiropractic seem to be longterm, as there was no consistent evidence of a return topretreatment Oswestry scores during the two years offollow up, whereas those treated in hospital may havebegun to deteriorate after six months or a year.
Chiropractic was particularly effective in those withfairly intractable pain-that is, those with a history andsevere pain. Although we have discussed the results interms of differences at the various follow up intervals,
the full effects of treatment are better thought of as anintegrated benefit throughout the two year follow up
period, represented by the area between the curves forthe two treatments. The greater proportions ofpatientstreated by chiropractic who were satisfied and relieved
at six weeks, when 90% ofpatients had provided follow
up data, strengthens the likelihood that the differencesin Oswestry scores and other variables later on,
when fewer patients have provided data, were true
differences.
The results from the secondary outcome measures(table VI) suggest that the advantage of chiropractic
starts soon after treatment begins. The reason for the
much larger advantage later on is not obvious. Part ofthe explanation could be that hospital treatment iseffective in the short term but not the longer term,
perhaps because it is not given for as long as chiropractic. The undoubted difficulties under which someof the participating physiotherapy departments were
working during the trial almost certainly meant thatthey were unable to give all the specific treatment theywould have wished to all patients.
A central question is the extent to which the results
could be due to biases and placebo effects. Patientswere deliberately sent follow up Oswestry questionnaires at home to minimise any chance that theiranswers might be affected by actual or perceived
influence by their therapist. Ideally, straight leg raisingand lumbar flexion should have been measured by anassessor who was blind to the treatment allocation. The
nurse coordinators, however, did not have the initial
results available at the time of the follow up measurements at six weeks. In addition nearly all the othersubsidiary measures suggested greater improvement
among those treated by chiropractic.
The consequences of biased outcome measures or ofa placebo effect associated with chiropractic would
almost certainly have been more evident when treatment was still in progress or just afterwards. In fact,
the main difference between hospital and chiropractic
treatment was seen from six months or a year onwards,
well after treatment and contact with therapists had
ended.
The fact that chiropractic treatment tended to be
more effective in those initially presenting to thechiropractors than in those presenting to hospitalraises the possibility that the self assessment by thepatients who presented to chiropractors may have been

1436

influenced by their expectation that chiropractic would
be effective. The results in all patients who had been
followed up for two years, however, indicate a similareffect of chiropractic in both referral groups (table V).
There were several differences between the two referralgroups that may have influenced response to treatment(these will be reported in detail elsewhere). For
example, a significantly higher proportion of patients
initially attending the chiropractors had had previous
episodes of back pain. Those initially attending chiropractors had also waited much less time for appointments for the current episode and scored significantly
less on questionnaires for depressive and inappropriate
symptoms and for somatic awareness than the patients
initially attending hospital. In addition, the analyses
among the (non-clinic) subgroups prespecified in theminimisation procedure were balanced for referralclinic, there being similar proportions initially presenting to chiropractors and to hospital in each of therandomised treatment groups. Yet the tendency forchiropractic to be more effective was not universalfor example, the absence of clear benefit in those withno previous history of back pain. Finally, the self
exclusion of many patients who initially presented tothe chiropractors probably resulted in only a few ofthese patients who might automatically have assessed
themselves as better after chiropractic or worse after
hospital treatment being included. In summary, it isunlikely that the benefits of chiropractic are the resultof biased outcome assessments or of a placebo effect.
Centres where chiropractic was more effective at six
weeks and six months and those where there was lessdifference between the two treatments at that stage
contributed to the results to about the same extent at ayear and two years. The sustained effect ofchiropractic
was therefore probably not due to a disproportionate
contribution from individual centres where there wasan obvious early benefit from chiropractic.
In the absence of any clear relation between thenumber of treatment sessions and outcome, specificcomponents of chiropractic responsible for its effectiveness have to be considered. An obvious possibility is
the use of high velocity, low amplitude manipulation in
virtually all the patients treated by chiropractic.
Another is that chiropractic was given for a longer
period than hospital treatment. Whatever the explanation for the difference between the two approaches,
however, this pragmatic comparison of two types oftreatment used in day to day practice shows thatpatients treated by chiropractors were not only noworse off than those treated in hospital but almost
certainly fared considerably better and that they
maintained their improvement for at least two years.
If our results are more widely applicable the practical
implications are far reaching. Consideration should begiven to recognising appropriately trained and experienced chiropractors and to providing chiropractic
within the NHS, either in hospitals or by purchasing
chiropractic treatment in existing clinics. Further
trials to identify the specific component(s) responsible
for the effectiveness of chiropractic should be undertaken. Whether the results of this trial can also be
applied to other heterodox regimens of manipulation isan open question.
We thank the nurse coordinators, medical staff, physiotherapists, and chiropractors in the 11 centres for their work,and Mr Alan Breen of the British Chiropractic Association forhis help. The centres were in Harrow, Taunton, Plymouth,
Bournemouth and Poole, Oswestry, Chertsey, Liverpool,
Chelmsford, Birmingham, Exeter, and Leeds. Without theassistance of many staff members in each the trial could
not have been completed. The study was supported by
the Medical Research Council, the National Back Pain
Association, the European Chiropractors Union, and theKing Edward's Hospital Fund for London.

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2 JUNE 1990

ADDENDUM-In view of the long term benefit apparently due to chiropractic we initiated a three year follow
up, sending multiple reminders to those initially not
responding. By mid April 1990-beyond the closing
date for the earlier results - data were available for 113
patients, representing a 79% response. At three years
the mean fall in Oswestry score for those treated bychiropractic was 9-6% points more than for thosetreated in hospital (p=0-01). The fall was greater(13 8% p=00003) among those presenting with current
episodes of more than a month's duration than for
those presenting with episodes of less than a month(5 3%, NS). Among those with a previous history ofback pain, the improvement in Oswestry score at three
years was 9-7% points greater in patients treated bychiropractic than those treated in hospital (p=002).
A similar difference between the two forms oftreatment (9-4%) was found among those with noprevious history of back pain, but numbers in thisgroup were smaller and the difference was not
significant.

1 British Medical Association. Alternative therapy. Report of the board of scienceand education. Spalding: Chamelcori Press, 1986:77.
2 Department of Health and Social Security Working Group on Back Pain.
Report to secretare of state for social services. ILondon: HMSO, 1979.
3 Smith R. Trouble ahead for clinical trials. BrMedJ7 1988;297:1567.
4 Frank AO, Hills JE. Spinal pain. In: Frank AO, Maguire GP, eds. Disabling
diseases: physical, environmental and psychosocial management. Oxford: Heiiiemann Medical Books, 1988:41-73.
5 Meade TW, Browne W, Mellows S, et al. Comparison of chiropractic andhospital outpatient management of low back pain: a feasibility study.
J Epidemiol Community Health 1986;40:12-7.
6 Fairbank J, Davies J, Coupar J, O'Brien JP. The Oswestry low back pain
disability questionnaire. Physiotherapy 1980;66:271-3.
7 Zinovieff A, Harborow PRH. Inclinometer for measuring straight-leg raising.
Rheumatology and Rehabilitation, 1975;14: 115.
8 McCray IF, Wright V. Measurement of back movement. Annals of Rheumatic
Diseases 1969;28:584.
9 Main CJ, Waddell G. The detection of psychological abnormality in chronic
low back pain using four simple scales. Current Concepts in Pain 1984;2:10-5.
10 Simon R. Sequential treatment assignment with balancing for prognostic
factors in the controlled clinical trial. Biometrics 1975;31:103-15.
11 Glass JB. Acute lumbar strain: clinical signs and prognosis. Practitioner

1979;222:821-5.
12 Wood PHN, Badley EM. Epidemiology of back pain. In: Javson MIV, ed. 7The
lumbar spine and back pain. 2nd ed. Tunbridge Wells: Pitman Medical, 1980.
13 Jayson MIV. A limited role for manipulation. BrMedj 1986;293:1454-5.
14 Grahame R. Clinical trials in low back pain. Clinics in Rheumatic Diseases
1980;6: 143-57.

(Accepted 30March 1990)

Low molecular weight heparins
and hypoaldosteronism

Centre Hospitalier
Universitaire de RouenBoisguillaume, BP 100,76233 Boisguillaume,
FranceH Levesque, MD, consultant
in internal medicine
S Verdier, house officer
N Cailleux, house officer
M C Elie-Legrand, MD,registrar
A Gancel, MD, consultant
J Y Borg, MD, consultant inhaemotolog
N Moore, MD, associate
professor ofpharmacology
H Courtois, MD, professor ofinternal medicine

Laboratoired'Hormonologie, Centre
Henri Bequerel, 76000
Rouen, France
J P Basuyau, MD, consultant
in radioimmunology

Correspondence to: Dr
Levesque.
BrAMedj 1990;300:1437-8

had been stopped. Blood was taken in the morning
after at least 12 hours' supine rest. It was analysed forserum sodium and potassium concentrations with anautomatic analyser (Technicon, Dublin, Ireland), andplasma aldosterone and cortisol concentrations andH Levesque, S Verdier, N Cailleux, M C Elie- renin activity with a radioimmunoassay. (The plasma
Legrand, A Gancel, J P Basuyau, J Y Borg, N samples were kept at - 20°C until the end of theMoore, H Courtois
analysis, and each patient's plasma was assayed for all
three periods simultaneously to eliminate interassay
Treatment with heparin can impair production of variations.)
aldosterone,' 2 though this is usually not clinicallyimportant. We diagnosed hyperkalaemia related to Results
hypoaldosteronism in a 79 year old woman who was
Twelve patients received enoxaparin (seven women,being treated with low molecular weight heparin; the five men; mean (SD) age 68-3 (11 7) years (range 37condition resolved when the treatment was withdrawn. 79)), and 15 received Fraxiparine (11 women, four
This prompted a prospective, randomised systematic men; mean age 70 3 (13-0) years (range 34-85)). The
study of the effects of the low molecular weight plasma aldosterone concentration had decreased after
heparins on adrenal function.
four days of treatment by a mean of 43-9 (4 11)%(p<0- 001). Three days after the treatment was stopped
the concentration had almost returned to initial values
Patients, methods, and results(table). No difference was found between patients
Twenty seven patients in hospital who were confined receiving enoxaparin and Fraxiparine. The two patientsto bed were given low molecular weight heparin, either taking frusemide, who initially had high plasma
Fraxiparine (3300 anti-factor X a units daily) or aldosterone concentrations also had decreased plasma
enoxaparin (2100 units daily), to prevent thrombo- aldosterone concentrations during treatment withembolic complications. The treatment was stopped low molecular weight heparin. In four patients
when the patients could get up. The doses were (three taking enoxaparin, one Fraxiparine) plasma
available prepackaged in subcutaneous injection aldosterone was not detectable during treatment.
syringes and designed to prevent venous thrombosis.
The mean serum potassium concentration increased
Patients who had diabetes mellitus or renal insuffi- significantly (p<0001) during treatment with bothciency, or were taking drugs known to interfere with drugs and decreased after treatment was stopped. The
aldosterone metabolism (converting enzyme inhibitors other variables measured did not change significantly.
or antialdosterone drugs) were not included. Twopatients continued taking frusemide (20 mg/day)during the study; none of the other patients took Comment
diuretics. All patients received the standard hospital
We found that low molecular weight heparindiet (normal salt intake) throughout the study.
inhibited the production of aldosterone, as does
Blood samples were taken before treatment, after standard heparin. The mechanism whereby heparinfour days of treatment, and three days after treatment inhibits aldosterone biosynthesis is not proved. Several
Mean (SD) values of biochemical variables measured in elderl, patients before, durlng (after four days' treatment), and (three days) after
treatment with low molecular weight heparins
FraxiparincPlasma aldosterone (pmol/l)
Plasma renin activitv (nmoVI/h)Cortisol(nmolUl)
Serumsodium(mmol/l)Serum potassium (mmolUl)

Enoxaparin

BeforeDuring

After

BeforeDuringAfter3326 (204 6)
33-4 (24-6)
511-1(114-3)
141(2 5)4-0 (0-3)

184-7 (109 2)**31 4 (14 9)2666 (150 4)*t
30 3 (26 0)
496-8(149-1)
139-6(1 8)
4-2 (0-4)2854 (105 8)
23-1 (14 2)
527-3(101-9)
139-6(2-6)
4 1 (0 3)1742 (113.7)**
25-5 (10 0)
489-4(150 2)
138-6(3 4)
4-5 (0 4)**2204 (97-8)*t
22 2 (7-7)
664-5(133)
138 5 (2 9)
4-3 (0-4)

516-1(156-2)
139-7(2 2)
4 4 (0 4)***p<005, **p<0.001 Compared with value before treatment by paired t test.
tp<0 05 Compared with value during treatment by paired t test

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2 JUNE 1990

1437