Prognosis for patients with chronic low back pain: inception cohort study

Dear Editor, dear colleagues,

I would like to thank Costa and colleagues (1) for their paper on
chronic low back pain (cLBP) prognosis. Their results are very important,
and their paper is very well done. However, I have an important concern:
Their population isn’t a natural history cohort, simply because patients
have been treated. The recruiting physicians, chiropractors and
physiotherapists had already received the current guidelines on low back
pain treatment (1), and we can presume they proposed either a “usual” or
an “evidence-based” treatment. We do not have any data on this, nor a
subgroup analysis according to the recruiters’ respective professions.
Both these elements would have been essential in order to more fully
understand the results obtained by the authors.

I also would like to introduce a main comment to the paper, relating
to the need to better define cLBP both epidemiologically and, more than
anything else, clinically. The usual definition of cLBP is
epidemiological: In the past, the cut-off among sub-acute and cLBP was 6
months (2), but very recently it was reduced to 3 months (3,4); Costa’s
results seem to confirm the medical feeling that this reduction is not
correct (5,6). A clinical definition of cLBP has existed for many years,
and it equates to “bio-psycho-social syndrome” (7). In the context of such
a reference, acute LBP is auto-resolving because it is “biological,” while
cLBP hardly recovers because it is “bio-psycho-social.” Sub-acute LBP,
between the previous ones, is the situation in which a conversion is
ongoing but the complete syndrome is not yet developed (8). Epidemiology
and clinics can meet, when recognising that time is the key factor in this
pathological evolution; but for individual patients, where expertise must
be combined with evidence in order to provide the best care (9), the
experienced physician tries to separate cLBP patients, in which the full
syndrome is clearly evident, from the sub-acute ones. The latter have only
partial problems, which can be mainly physical, psychological or even
social, while the former show a conglomeration of all these elements, with
a series of perpetuating vicious cycles well established (8). Sub-acute
patients rarely have important de-conditioning or dysfunctional
disturbances, while chronic patients become disillusioned with the
treatment efficacy and possibility of recovery while characteristically
harbour the hope of finding the “magic bullet” that will solve the problem
(10). Unfortunately, many patients cannot be classified clinically, and we
lack tests to define the differences so that we can proceed beyond the
expertise of the individual physician. Even disability scales allow one to
distinguish high from low disability populations within the general cLBP
population (4,5) but they do not distinguish patients who are sub-acute
from those who are chronic. Consequently, time remains the best way to
separate these populations, and epidemiology wins while we wait for better
clinical methods. However, we need clear-cut timings. Looking at the data
of Costa and colleagues (1), while at 3 months there is still a 42%
probability of full recovery, over time this decreases significantly.
Perhaps, and this should be carefully investigated in future studies, 9
months is a better point at which to define chronic patients (6% recovery
in 3 more months), assuming, of course, the possibility of observing a
natural history cohort. Meanwhile, we must wait for clinical methods by
which to achieve the best classification.

References

1. Costa Lda C, Maher CG, McAuley JH, Hancock MJ, Herbert RD,
Refshauge KM, et al. Prognosis for patients with chronic low back pain:
inception cohort study. Bmj 2009;339:b3829.

2. Bigos S. Acute low back pain problems in adults: Clinical Practice
Guidelines n° 14. Rockville, MD: Agency for Health Care Policy and
Research, Public Health Service, US Department of Health and Human
Services, 1994.

3. Airaksinen O, Brox JI, Cedraschi C, Hildebrandt J, Klaber-Moffett
J, Kovacs F, et al. Chapter 4 European guidelines for the management of
chronic nonspecific low back pain. Eur Spine J 2006;15(Supplement 2):s192-
s300.

4. Negrini S, Giovannoni S, Minozzi S, Barneschi G, Bonaiuti D,
Bussotti A, et al. Diagnostic therapeutic flow-charts for low back pain
patients: the Italian clinical guidelines. Eura Medicophys 2006;42(2):151-
70.

5. Negrini S. Usefulness of disability to sub-classify chronic low
back pain and the crucial role of rehabilitation. Eura Medicophys
2006;42(3):173-5.

6. Negrini S. The low back pain puzzle today. Eura Medicophys
2004;40(1):1-8.

7. Waddell G. 1987 Volvo award in clinical sciences. A new clinical
model for the treatment of low-back pain. Spine 1987;12(7):632-44.

8. Negrini S, Bonaiuti D, Monticone M, Trevisan C. Medical Causes of
Low Back Pain. In: Slipman C, Simeone F, Derby R, editors. Interventional
Spine: an algorithmic approach. London: Elsevier, 2005.

9. Sackett DL, Rosenberg WM. The need for evidence-based medicine. J
R Soc Med 1995;88(11):620-4.

10. Delitto A. Research in low back pain: time to stop seeking the
elusive "magic bullet". Phys Ther 2005;85(3):206-8.

Competing interests:
None declared