Acute low back pain: systematic review of its prognosis
BMJ 2003; 327 doi: https://doi.org/10.1136/bmj.327.7410.323 (Published 07 August 2003) Cite this as: BMJ 2003;327:323
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Pengel et al conclude in their systematic review that back pain
improves rapidly and that most patients return to work within one
month.(1) However, their results are seriously biased by restricting their
review to studies that only included patients with back pain lasting less
than three weeks. The argument that thereafter the symptoms have
disappeared quickly does not sound valid to me, because there is no reason
that within the first six weeks the course of the disorder is
substantially different.
The conclusions on return to work are even more
biased. First, the authors include studies in which it is unclear if all
patients are on sick leave at the beginning of the study, because the data
are based on compensation claims.(2) Secondly, the restriction to
complaints less than three weeks, exclude many interesting cohort studies
on return to work that do inform about prognostic factors. (3;4) Finally,
the conclusion that failure to return to work is of limited clinical value
contrasts with the enormous burden of occupational disability as a result
of low back pain.
I hope that sensible clinicians confronted with patients
with low back pain will disregard the results of this systematic review
and will use other systematic reviews with less biased results. (5)
Reference List
(1) Pengel LH, Herbert RD, Maher CG, Refshauge KM. Acute low back
pain: systematic review of its prognosis. BMJ 2003; 327:323-327.
(2) Hazard RG, Haugh LD, Reid S, Preble JB, MacDonald L. Early
prediction of chronic disability after occupational low back injury. Spine
1996; 21(8):945-951.
(3) Infante-Rivard C, Lortie M. Prognostic factors for return to
work after a first compensated episode of back pain. Occup Environ Med
1996; 53(7):488-494.
(4) van der Weide WE, Verbeek JH, Salle HJ, van Dijk FJ. Prognostic
factors for chronic disability from acute low-back pain in occupational
health care. Scand J Work Environ Health 1999; 25(1):50-56.
(5) Pincus T, Burton AK, Vogel S, Field AP. A systematic review of
psychological factors as predictors of chronicity/disability in
prospective cohorts of low back pain. Spine 2002; 27(5):E109-E120.
Competing interests:
I reviewed the paper for BMJ
Competing interests: No competing interests
Systematic review of prognosis in acute low back pain: bias in
indentification of relevant studies
Editor - In our response to Pengels' et al article we concluded that
authors failed to identify several relevant studies, which provide
additional evidence that clinical course of of low back pain presented in
general practice is less favourable than expected.[1] Our primary aim
was to point out that problems in indentification of prognostic
studies are associated with high risk of missing relevant data. [2]
Pengel et al criticised us for not providing any evidence of our
claims.[3] They disagreed with our explanation that inclusion of patients
with longer duration of pain might be useful as it can provide more
information regarding outcome. They argued that "this ignores the
possibility that survival cohorts could provide seriously biased estimates
of prognosis." [4] Unfortunately, they did not pay attention to our notion
that heterogeneous cohorts can be stratified in the analysis." [2]
Further to our previous objections we would like to add that Pengel
et al did not attempt to identify unpublished literature and search in
grey literature databases. No analysis such as funnel plots were
conducted to assess bias in location and selection of studies.[5] Thus, it
seems reasonable to asume that strict inclusion criteria and relatively
narrow search strategy might contribute to missing of relevant
studies.
Michal R Pijak, Consultant in rheumatology and clinical immunology.
Department of Clinical Immunology, Institute of Preventive and Clinical
Medicine, Limbova 14, 833 01 Bratislava, Slovakia, pijak@upkm.sk
Frantisek Gazdik, Research fellow. Department of Clinical Immunology,
Institute of Preventive and Clinical Medicine, Limbova 14, 833 01
Bratislava, Slovakia, gazdik@upkm.sk
1. Pijak MR, Gazdik F. Systematic review of prognosis in acute low
back pain: danger of high publication bias.
http://bmj.com/cgi/eletters/327/7410/323#35534, 9 Aug 2003
2. Altman DG. Systematic reviews of evaluations of prognostic
variables. In: Egger M, Davey Smith G, Altman DG, eds. Systematic reviews
in health care. Meta-analysis in context. 2nd ed. London: BMJ Books,
2001:228-247.
3. Herbert RD, Pengel LHM, Maher CG, Refshauge KM. Re: Systematic
review of prognosis in acute low back pain: danger of high publication
bias. http://bmj.com/cgi/eletters/327/7410/323#35556, 10 Aug 2003
4. Herbert RD, Pengel LHM, Maher CG, Refshauge KM Re: Re:Re:
Systematic review of prognosis in acute low back pain: danger of high
publication bias. http://bmj.com/cgi/eletters/327/7410/323#35836, 18 Aug
2003
5. Egger M, Smith GD. Bias in location and selection of studies. BMJ.
1998;316:61-6.
Competing interests:
None declared
Competing interests: No competing interests
In their Rapid Response, Samanta et al. claim that "Pengel et al.
have provided good evidence that most acute low back pain (LBP) improves
within one month, with further improvements by three months, and a small
possibility of recurrence up to twelve months". [1]
However, Samanta et al missed the main point of Pengel et al.´s
review that "Although most people return to work within 12 months, low
levels of pain and disability persist." [2] Furthermore, Pengel et al.
clearly demonstrated that 73% of patients had at least one recurrence
within 12 months. These observations may have an important practical
implication. Namely, this evidence suggests that, in addition to the pain
intensity, the episodic nature of LBP can also markedly affect the
ability of the patient to function both at work and in personal life.[3]
Another overly optimistic and unsupported claim of Samanta et al. is
that "... a small proportion of patients with acute LBP may develop
chronic pain..." However, the evidence provided by Pengel et al. points
to the opposite conclusion, that LBP should rather be viewed as a
chronic disease, with an unpredictable course. This hypothesis is
further supported by the recent finding, that back pain is strongly
associated with degeneration of the intervertebral disk.[4]
As reviewed by Urban and Robert, the discs degenerate far
sooner than other musculoskeletal tissues and the multifactorial nature
of disc degeneration may have an important genetic component.[5] In
light of these new facts, Urban and Robert correctly point out that
unless more research is devoted to intervertebral disc biology, back
pain will remain a poorly diagnosed and poorly treated syndrome.
References
1. Samanta,A, Samanta J, Kendall J. Acute low back pain: early
intervention to reduce chronicity.
http://bmj.com/cgi/eletters/327/7410/323#35798, 17 Aug 2003
2. Pengel LHM, Herbert RD, Maher CG, Refshauge KM. Acute low back
pain: systematic review of its prognosis. BMJ 2003; 327: 323..
3. McGorry RW, Webster BS, Snook SH, Hsiang SM. The relation between
pain intensity, disability, and the episodic nature of chronic and
recurrent low back pain. Spine 2000;25:834-41
4. Luoma K, Riihimaki H, Luukkonen R, Raininko R, Viikari-Juntura E,
Lamminen A. Low back pain in relation to lumbar disc degeneration. Spine.
2000;25:487-92.
5. Urban JP, Roberts S. Degeneration of the intervertebral disc.
Arthritis Res Ther. 2003;5:120-30.
Competing interests:
None declared
Competing interests: No competing interests
Pijak and Gazdik (1) initially claimed we missed four relevant
studies in our systematic review of prognosis of back pain (2). We
explained that three of the studies were not eligible and one was, in
fact, included in the review (3).
Pijak and Gazdik do not concede their error, but they do raise a new
objection (4). They contend that "inclusion of patients with longer
duration may be useful as it can provide more information regarding the
outcome". This ignores the possibility that survival cohorts could provide
seriously biased estimates of prognosis (5).
The cohort study of Croft et al (6) recruited a survival cohort of
patients presenting to general practice with low back pain but separately
reports data for the inception sub-cohort of patients with pain of <_1 week="week" or="or" _2-3="_2-3" weeks.="weeks." _73="_73" of="of" subjects="subjects" with="with" pain="pain" less="less" than="than" _3="_3" weeks="weeks" at="at" first="first" consultation="consultation" reported="reported" and="and" disability="disability" months="months" _64="_64" _12="_12" calculated="calculated" from="from" table="table" _5.="_5." this="this" is="is" consistent="consistent" our="our" conclusion="conclusion" that="that" typically="typically" persist="persist" for="for" long="long" periods="periods" it="it" suggests="suggests" the="the" low="low" average="average" levels="levels" are="are" due="due" to="to" in="in" a="a" large="large" proportion="proportion" patients.="patients." p="p"/> 1. Pijak MR, et al. Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 9 Aug 2003.
2. Pengel LHM, et al. Acute low back pain: systematic review of its
prognosis. BMJ 2003; 327:323.
3. Herbert RD, et al. Re: Systematic review of prognosis in acute low back
pain: danger of high publication bias. BMJ.com, 11 Aug 2003.
4. Pijak MR, et al. Re:Re: Systematic review of prognosis in acute low
back pain: danger of high publication bias. BMJ.com, 12 Aug 2003.
5. Fletcher RH, et al. Clinical epidemiology: the essentials. Baltimore:
Williams & Wilkins, 1996.
6. Croft PR, et al. Outcome of low back pain in general practice: a
prospective study. BMJ 1998;316:1356-9.
Competing interests:
None declared
Competing interests: No competing interests
Sir,
As noted in the Paper from Pengel and coll. after an episod of low back
pain, people rapid improve, with early return to work. But as also noted,
there is an recurrence within a year in an large majority:in Switzerland,
Waldburger et coll. noted 80% of reccurence during the first year. What
that this mean? It means that our traditionnal guide-lines should be
revised, and according to the work-profil of the patient we have to adapte
treatments, to learn who to face the pain but also the work-place.
There is a place for a reeducation program, including ergotherapeutic
training at the same time that the patient learns how to do an effective
training program. But we do not have to forget the psychological factors,
that would be of interest in the mor chronic situation
Competing interests:
None declared
Competing interests: No competing interests
Editor
Pengel et al., have provided good evidence that most acute low back
pain improves within one month, with further improvements by three months,
and a small possibility of recurrence up to twelve months [1]. Whilst this
prognosis is encouraging it is important to address how recovery might be
facilitated and relapses reduced.
The effectiveness of the majority of interventional modalities for
acute low back pain is either unknown or has relatively weak supporting
evidence [2]. However, the use of non-steroidal anti-inflammatory drugs
(NSAIDs) and advice to stay active promotes symptomatic recovery.
Systematic reviews and RCTs in patients with acute low back pain show that
NSAIDs are more effective than placebo for pain relief [2]. They also
produce an overall improvement, and facilitate recovery by as early as one
week [2]. Advice to stay active in acute low back pain increases the
speed of recovery, reduces long term disability and promotes early return
to work [2].
It is recognised that a small proportion of patients with acute low
back pain may develop chronic pain, which accounts for a high level of
absenteeism from work [2]. As in cases of chronic back pain [3], it is
important that a clear message and positive message should be given to
patients with acute low back pain if long-term problems are to be avoided.
Patients should be told from the onset when they present in primary care
that the prognosis for recovery in acute low back pain is good. NSAIDs can
speed recovery and advice should be given regarding staying active,
followed by an incremental exercise and fitness programme for the long
term [4, 5].
Ash Samanta consultant rheumatologist
Jo Samanta clinical research assistant
Julia Kendall gp clinical assistant
Dept of Rheumatology
Leicester Royal Infirmary
University Hospitals of Leicester NHS Trust
Leicester LE1 5WW
References
1 Pengel L H M, Herbert R D, Maher C G, Refshauge K M. Acute low
back pain: systematic review of its prognosis. BMJ 2003; 327: 323-325
2 van Tulder M, Koes B. Low back pain and sciatica: acute. Clin
Evid Concise 2002; 8: 226-228
3 Samanta J, Kendall J, Samanta A. Chronic low back pain. BMJ 2003;
326:535
4 Samanta A, Beardsley J. Low back pain: which is the best way
forward? BMJ 1999; 318: 1122-1123
5 Goh L, Bawendi A, Samanta J, Samanta A. An evidence-based approach
to the management of low back pain and sciatica: how the evidence is
applied in clinical cases. Musculoskeletal Care 2003 In Press
Competing interests:
None declared
Competing interests: No competing interests
We disagree with Herbert et al´s statement that studies we cited
were not eligible for the review because of more than three weeks
duration of LBP (1). Inclusion of patients with longer duration of acute
episode does not mean that only the cohorts of more than three weeks
duration of LBP were included. On the contrary, inclusion of patients
with longer duration may be useful as it can provide more information
regarding the outcome.
For example in the Croft et al´s study the median duration of
symptoms was three weeks (interquartile range 2-9 weeks) (2). However, the
patients were stratified according to duration of episode into three
groups as showed in the table five of this paper. Most subjects who
reported a duration of less than two weeks had recovered by 12 months,
whereas those consulting about episodes of longer duration were less
likely to have recovered. Thus, while homogeneity is often desirable,
heterogeneous cohorts can be stratified in the analysis.
Michal R Pijak, Consultant in rheumatology and clinical immunology.
Department of Clinical Immunology, Institute of Preventive and Clinical
Medicine,
Limbova 14, 833 01 Bratislava, Slovakia, pijak@upkm.sk
Frantisek Gazdik, Research fellow.
Department of Clinical Immunology, Institute of Preventive and Clinical
Medicine,
Limbova 14, 833 01 Bratislava, Slovakia, gazdik@upkm.sk
References
1. Herbert. RD. Pengel LHM, Maher CG, Refshauge KM. Re: Systematic
review of prognosis in acute low back pain: danger of high publication
bias. http://bmj.com/cgi/eletters/327/7410/323#35556, 10 Aug 2003
2. Croft PR, Macfarlane GJ, Papageorgiou AC, Thomas E, Silman AJ.
Outcome of low back pain in general practice: a prospective study. BMJ
1998;316:1356-9.
Competing interests:
None declared
Competing interests: No competing interests
The Dangers of Too Rapid a Response
In their Rapid Response Pijak and Gazdik claim our failure to locate
four relevant studies illustrates "the high risk of missing relevant
data". There may be a risk of missing relevant data, but Pijak and Gazdik
have not provided any evidence of that. Three of the four studies they
cite were not eligible for the review because the studies included
survival cohorts with low back pain of more than 3 weeks duration (1-3).
The fourth was included in the review (4).
1. Thomas E, Silman AJ, Croft PR, Papageorgiou AC, Jayson MIV,
Macfarlane GJ. Predicting who develops chronic low back pain in primary
care: a prospective study. BMJ 1999;318:1662-7.
2. Van den Hoogen HJ, Koes BW, van Eijk JT, Bouter LM, Deville W. On the
course of low back pain in general practice: a one year follow up study.
Ann Rheum Dis 1998;57:13-9.
3. Carey TS, Garrett J, Jackman A, McLaughlin C, Fryer J, Smucker DR. The
outcomes and costs of care for acute low back pain among patients seen by
primary care practitioners, chiropractors, and orthopedic surgeons. The
North Carolina Back Pain Project. N Engl J Med 1995;333:913-7.
4. Schiottz-Christensen B, Nielsen GL, Hansen VK, Schodt T, Sorensen HT,
Olesen F. Long-term prognosis of acute low back pain in patients seen in
general practice: a 1-year prospective follow-up study. Fam Pract
1999;16:223-32.
Competing interests:
None declared
Competing interests: No competing interests
Editor: Pengel et al carried out a systematic review of the evidence
regarding prognosis of acute low back pain (LBP). (1) Although the papers
were identified from a comprehensive literature search recommended by the
Cochrane Back Review Group, only two of the 15 eligible studies assessed
provided follow up data beyond three months.
However, several missed publications provide additional evidence
that clinical course of LBP presented in general practice, for the most
patients, clearly is less favourable than expected. (2-5) It takes more
than just a few weeks to recover, and relapses occur within a year in most
cases. Thus it seems that LBP should be rather viewed as a chronic problem
with extremely unpredictable course. In this context it is useless to
speculate whether chronic low levels of pain are due to persistence of
the original episode or to recurrent eipisodes.
With respect to prognostic factors of LBP, Pengel et al note that
"only one relevant, methodologically strong paper provided evidence of a
clinically useful predictor of outcome." The authors, however, failed to
identify another relevant paper showing that the presence of persistent
LBP is not only determined by psychological and clinical factors at the
onset but also before the onset of the consulting episode. (3)
In summary, difficulties in searching the literature for prognostic
studies of LBP is associated with high risk of missing relevant data.
Systematic review using individual patient data may overcome many of
these difficulties.
Michal R Pijak, Consultant in rheumatology and clinical immunology.
Department of Clinical Immunology, Institute of Preventive and Clinical
Medicine,
Limbova 14, 833 01 Bratislava, Slovakia, pijak@upkm.sk
Frantisek Gazdik, Research fellow.
Department of Clinical Immunology, Institute of Preventive and Clinical
Medicine,
Limbova 14, 833 01 Bratislava, Slovakia, gazdik@upkm.sk
1. Pengel LHM, Herbert RD, Maher CG, Refshauge KM. Acute low back
pain: systematic review of its prognosis. BMJ 2003; 327: 323.
2. Schiottz-Christensen B, Nielsen GL, Hansen VK, Schodt T, Sorensen
HT, Olesen F. Long-term prognosis of acute low back pain in patients seen
in general practice: a 1-year prospective follow-up study. Fam Pract
1999;16:223-32.
3. Thomas E, Silman AJ, Croft PR, Papageorgiou AC, Jayson MIV,
Macfarlane GJ. Predicting who develops chronic low back pain in primary
care: a prospective study. BMJ 1999;318:1662-7.
4. Van den Hoogen HJ, Koes BW, van Eijk JT, Bouter LM, Deville W. On
the course of low back pain in general practice: a one year follow up
study. Ann Rheum Dis 1998;57:13-9.
5. Carey TS, Garrett J, Jackman A, McLaughlin C, Fryer J, Smucker DR.
The outcomes and costs of care for acute low back pain among patients seen
by primary care practitioners, chiropractors, and orthopedic surgeons. The
North Carolina Back Pain Project. N Engl J Med 1995;333:913-7.
Competing interests:
None declared
Competing interests: No competing interests
RE: Bias in review of back pain prognosis
Verbeek [1] claimed that the results of our systematic review [2] are
seriously biased because we only included patients with back pain lasting
less than three weeks. According to Altman [3], systematic reviews of
prognostic variables should include participants in the early stage of the
disease. If we had included participants with a low back pain duration of
up to 6 weeks, which is close to the transition to subacute low back pain,
we could no longer speak of a true inception cohort. There are two
problems with including such a heterogenous cohort. First, a heterogenous
cohort would be expected to have highly variable outcomes (more variable,
at any rate, than the homogeneous cohort assembled at an early and uniform
point in the course of this condition). Our data (Figure 1) show that the
study participants experienced rapid improvements in pain and disability
in the first month. By six weeks participants had already improved
significantly; typically pain and disability at 6 weeks were only a third
of initial values. A second and more significant problem is that many
people no longer have back pain at 6 weeks, so those recruited with 6
weeks of back pain cannot be representative of all people who experience
back pain. Clearly the prognosis of the subset of people with back pain
persisting to six weeks (the “survival cohort”) could be very different
from the target population (all people with low back pain).
Verbeek’s last claim was “the conclusion that failure to return to
work is of limited clinical value contrasts with the enormous burden of
occupational disability as a result of low back pain”. We actually were
commenting on a paper by Hazard et al [4] and noted that the Vermont
Disability Prediction Questionnaire as a predictor of failure to return to
work may be of limited clinical utility. We did not state that failure to
return to work is of limited clinical value. If we held this opinion we
would not have prospectively specified this as an outcome.
References
1. Verbeek J. Bias in review of back pain prognosis. BMJ.com, 11
September 2003
2. Pengel LH, Herbert RD, Maher CG, Refshauge KM. Acute low back
pain: systematic review of its prognosis. BMJ 2003; 327:323-327.
3. Altman DG. Systematic reviews of evaluations of prognostic
variables. BMJ 2001, 323, 224-228.
4. Hazard RG, Haugh LD, Reid S, Preble JB, MacDonald L. Early
prediction of chronic disability after occupational low back injury. Spine
1996; 21, 945-951.
Competing interests:
None declared
Competing interests: No competing interests