Prognosis in patients with recent onset low back pain in Australian primary care: inception cohort study

Dear Editor,

Henschke et al. [1] repeatedly compare the results of their study of
“recent onset” low back pain (LBP) to those of our own study published in
the Journal in 1994 [2] and apparently fail to explain the marked
difference in the results in terms of delay before recovery. In our
opinion, the different results are a consequence of the study methods,
which were much more dissimilar than that acknowledged by Henschke et al.,
and also of conceptual and nosological approaches, which were even more
dissimilar.

Henschke et al. stated they conducted an “inception cohort” study, as we
did both in 1991 [2] and also in 1999 [3]; however, it appears that they
included subjects who had been suffering for up to two weeks, a delay
which was associated with 90% recovery in our studies (we are thus very
surprised that they found “a recovery rate virtually unchanged at two
weeks” when considering the subset of subjects whose back pain lasts only
for up to 3 days).

It also appears that they only required a one-month symptom-free interval
for including patients in the cohort (three months in our studies): this
lax definition of “recent onset” LBP allows the inclusion of “relapsing-
remitting” chronic LBP subjects and may therefore result in the observed
prognosis being worse.

It also appears that up to 20% of the subjects of their study presented
with leg pain (although it was stated patients with radiculopathy were
excluded). Obviously this subgroup of patients with mild sciatica or
“borderline” LBP did have a worse outcome than the population as a whole.

It also appears that 81% of patients were included by physiotherapists or
chiropractors. These professionals may provide inadequate and worrying
information about LBP and possibly even harmful therapeutic manoeuvres
(and, at least, are much more “stigmatizing” than acetaminophen prescribed
by GPs); this design is also open to huge selection biases as self-
referral to physiotherapists or chiropractors indicates that the subjects
are familiar with, and probably even have long-lasting experience of, LBP.

We also note that practitioners were encouraged financially to discover
“serious pathology”, which necessarily increased the burden of
investigation, anxiety and thereby delayed recovery.
These are major differences with respect to our studies regarding the
selection of patients. Furthermore, it appears that recovery was defined
using a question such as “how much LBP have you had during the past week”
asked during the first follow-up interview which took place at 6 weeks (in
our study we used a diary including standardized instruments which
patients filled in prospectively).

In the light of these differences, we disagree with the conclusion of
Henschke et al. that “prognosis is not as favourable as claimed in
patients with acute LBP in primary care” and we disapprove this rhetoric
of fear constructed on results from a cohort of subjects accumulating bad
prognosis factors, irrespective of whether it is motivated by laudable
reasons (fund raising for research) or less laudable ones (defending
corporative interests of “professionals of LBP”).

We agree with Henschke et al. that “further studies are warranted”, but we
believe further studies should make use of optimised methods and
appropriately defined concepts. Indeed, it is remarkable that conceptual
and nosological thinking has almost disappeared from current clinical
research in LBP. Using a “black box” approach instead of refining current
classifications [4] and thereby not distinguishing between established
nosological entities such as back pain and sciatica (with quite different
natural history and kinetics of recovery [5]) and concepts such as “recent
onset” and “acute”, can only be detrimental both to medical science and
the care of (millions of) patients with these conditions.

J. Coste

Rheumatologist, Professor of Biostatistics
Hôpital Cochin, Université Paris Descartes, Paris, France

J.B Paolaggi

Professor of Rheumatology

Académie Nationale de Médecine, Paris, France

References

1. Henschke N, Maher CG, Refshauge KM, Herbert RD, Cumming RG,
Bleasel J, York J, Das A, McAuley JH. Prognosis in patients with recent
onset low back pain in Australian primary care: inception cohort study.
BMJ. 2008 Jul 7;337:a171.

2. Coste J, Delecoeuillerie G, Cohen de Lara A, Le Parc JM,
Delecoeuillerie G, Paolaggi JB. Clinical course and prognostic factors of
acute low-back pain. An inception cohort study in primary care practice.
BMJ 1994; 308 : 577-580.

3. Coste J, Lefrancois G, Guillemin F, Pouchot J. Prognosis and
quality of life in patients with acute low back pain: Insights from a
comprehensive inception cohort study. Arthritis Rheum. 2004; 51: 168-76.

4. Coste J, Spira A, Ducimetière P, Paolaggi JB. Clinical and
psychological diversity of non-specific low-back pain. A new approach
towards the classification of clinical subgroups. J. Clin. Epidemiol 1991;
11 : 1233-45.

5. Paolaggi JB. Natural history of non specific neuralgias of the
limbs. Exponential kinetics of the root pain recovery in sciatica and
femoral neuralgia; uncertain kinetics for brachial neuralgia. Bull Acad
Natl Med. 2003; 187: 1631-45.

Competing interests:
None declared