European Journal of Pain 2013 (Jan); 17 (1): 5–15 ~ FULL TEXT
C.J. Itz, J.W. Geurts, M. van Kleef, P. Nelemans
Department of Health Service Research,
Maastricht, The Netherlands.
BACKGROUND AND OBJECTIVE: Non-specific low back pain is a relatively common and recurrent condition for which at present there is no effective cure. In current guidelines, the prognosis of acute non-specific back pain is assumed to be favourable, but this assumption is mainly based on return to function. This systematic review investigates the clinical course of pain in patients with non-specific acute low back pain who seek treatment in primary care.
DATABASES AND DATA TREATMENT: Included were prospective studies, with follow-up of at least 12 months, that studied the prognosis of patients with low back pain for less than 3 months of duration in primary care settings. Proportions of patients still reporting pain during follow-up were pooled using a random-effects model. Subgroup analyses were used to identify sources of variation between the results of individual studies.
RESULTS: A total of 11 studies were eligible for evaluation. In the first 3 months, recovery is observed in 33% of patients, but 1 year after onset, 65% still report pain. Subgroup analysis reveals that the pooled proportion of patients still reporting pain after 1 year was 71% at 12 months for studies that considered total absence of pain as a criterion for recovery versus 57% for studies that used a less stringent definition. The pooled proportion for Australian studies was 41% versus 69% for European or US studies.
CONCLUSIONS: The findings of this review indicate that the assumption that spontaneous recovery occurs in a large majority of patients is not justified. There should be more focus on intensive follow-up of patients who have not recovered within the first 3 months.
From the FULL TEXT Article:
Non-specific low back pain (LBP) is a relatively
common and recurrent condition with major medical
and economical implications for which today there is
no effective cure (van Tulder et al., 1995; Roelofs
et al., 2008; Becker et al., 2010; van Middelkoop
et al., 2011). Most treatment strategies and guidelines
are based on the assumption that the prognosis
of acute LBP is favourable and that the pain resolves
spontaneously in the majority of patients (Spitzer
et al., 1987; Andersson, 1999; van Tulder et al.,
2006). However, the evidence for this statement is
mainly based on occupational studies in which
‘return to work’ or ‘recovery from disability’ is
studied (Spitzer et al., 1987; Croft et al., 1998;
Andersson, 1999). These studies indicate that most
back pain patients return to function, this in spite of
their pain (Bowey-Morris et al., 2011). There seems
to be a lack of information on the course of acute
non-specific LBP when pain rather than return to
work is considered as endpoint.
A previous systematic review that assessed the prognosis
of acute LBP found high rates of LBP after 1 year
of follow-up (42% to 75%) (Hestbaek et al., 2003).
However, this aforementioned review did not evaluate
the clinical course by providing information on proportions
of patients with early onset of LBP and also
included studies that were not performed in primary
The present review is designed to investigate the
clinical course of pain in patients with non-specific LBP
of less than 3 months of duration, with a follow-up of at
least 12 months, and set in primary care.
This systematic review investigates the clinical
course of low back pain in primary care settings.
Nonspecific low back pain is a relatively common
and recurrent condition for which at present
there is no effective cure. In current guidelines
the prognosis of acute nonspecific back pain is
assumed to be favourable but this assumption is
mainly based on return to function. Included
were 11 prospective studies, with follow-up of at
least 12 months, which studied the prognosis of
patients with back pain for less than 3 months of
duration set in primary care.
What does this review add? |
This review shows that after 3 months recovery
is observed in 33% and after one year 65%
A literature search was performed for suitable articles
published between 1990 and 2010 in English, German
and Dutch, referenced on MEDLINE and PUBMED,
and EMBASE (Table 1). The search was started at 1990
because in 1987 Spitzer wrote his monograph: Scientific
approach to the assessment and management of activityrelated
spinal disorders. A monograph for clinicians. Report
of the Quebec Task Force on Spinal Disorders (Spitzer et al.,
1987). This study had a major impact on the treatment
of LBP, and still has impact today. Therefore, we were
basically interested in evidence provided by studies
that were published in the years following this
The following keywords were used: LBP and sciatica,
follow-up and prognosis, onset or inception cohort,
acute or sub-acute. Two authors (C.I. and J.G.) independently
screened the titles, abstracts and keywords
of all references identified by the literature search to
determine if they addressed the research question.
Full-text publications were retrieved for potentially
relevant articles. The bibliographies of the retrieved
articles were screened for additional relevant papers.
Studies were considered eligible for review if they
allowed for evaluation of the clinical course of nonspecific
LBP and met the following inclusion criteria:
(1) the study was prospective in design (prospective
cohort study or controlled trial);
(2) the study population consisted of adult patients with non-specific LBP;
(3) patients were included within 3 months after
LBP onset with follow-up data of at least 1 year;
(4) one of the study outcomes was pain and the proportion
of patients with or without pain could be
extracted from the study or could be established after
contacting the (corresponding) author;
(5) the patients were recruited in primary care settings; and
(6) data were available from patients who did not
undergo an intervention or from patients who underwent
an intervention that was reported not to affect
the pain scores.
Studies were excluded if:
(1) the study
population included patients with trauma, surgery
and/or injury; and
(2) the selection of patients was
restricted to special work conditions or pregnant
When multiple studies were identified with
overlap in study populations, only the original study
was included to avoid potential duplication of datasets.
Two authors (C.I. and J.G.) independently extracted
data from selected studies on proportion of pain and
relevant population and study characteristics. The
main study parameter is the proportion of patients
with pain at 12 months. Other parameters of interest
were proportions of patients with pain at 1, 3 and 6
months. In cases where absolute numbers of patients
with pain at 12 months could not be derived from the
publication and/or the definition of recovery from
pain was unclear, the authors were contacted for additional
Study characteristics considered of interest were:
sample size; country where the study was performed;
year of publication; percentage of male participants;
mean age; definition and localization of LBP; mean
time since onset; and definition of recovery from pain.
Items concerning representativeness of the target
population such as response and dropout rates during
follow-up were also recorded.
For assessment of the quality of the articles modified,
Leboeuf criteria were used (Leboeuf-Yde and Lauritsen,
1995) (Table 2). This method uses criteria related
to the representativeness of the study sample, the
quality of data and the definition of LBP. An additional
item concerning analysis of data (item E) was added.
The authors (C.I. and J.G.) independently scored these
items. In cases of disagreement, discrepancies were
discussed with a third author (P.N.) and consensus was
achieved. Each study was assigned a score, expressed
as a proportion of fulfilled criteria out of the total
number of relevant criteria. Information provided in
the published report of the study was scored as present
(+ criterion fulfilled), absent (– criterion not fulfilled)
or 'not applicable' (NA) (Table 3). If the study design
appeared to allow for the omission of a certain criterion,
it was noted as methodologically acceptable (+).
The main study parameter for this review was the
proportion of patients with pain. Therefore, if data on
pain were presented in a way that did not allow for
calculation of proportions, the score ‘not applicable’
was used for item E, otherwise it was scored as present
(+ criterion fulfilled). For each study, only one of the
items G, H and I was scored depending on the method
that was used to evaluate presence of pain (questionnaire,
interview or examination).
We distinguished between studies with a quality
score of >70% versus studies with a score of ≤ 70% to
evaluate whether the quality of studies affects the
proportion of patients with pain after 1 year. The cutoff
point of 70% was arbitrarily chosen.
The primary outcome of interest is the proportion of
patients who still suffer from LBP at 1 year after onset.
Secondary outcome measures were the proportion of
patients with LBP 1, 3 and 6 months after onset.
Proportions of patients with pain at 12 months, and
if available at 1, 3 and 6 months, were derived from
studies. For each time point, proportions were pooled
using random-effects models as proposed by DerSimonian
and Laird using the inverse of the standard errors
of the proportion of individual studies as weights
(DerSimonian and Laird, 1986). The I2 index was used
to test for heterogeneity between study results. Significance
of this index indicates that differences
between studies cannot be solely attributed to sampling
variation and that differences in study population,
design and analysis are responsible for variation
between study results (Higgins et al., 2003).
Subgroup analyses were used to evaluate whether
presence or absence of a specific study characteristic is
associated with higher or lower pooled proportions of
patients with pain at 12 months. For this purpose,
studies were categorized into subgroups according to
the presence or absence of a specific study characteristic.
The differences in pooled proportions between
subgroups with corresponding 95% confidence intervals
(CIs) were calculated to evaluate the magnitude
of effect of the study characteristic on study result and
to test the effect for statistical significance.
All analyses were performed with the statistical
package STATA (Copyright 2009, StataCorp LP, TX,
USA). P-values ≤ 0.05 were considered to indicate
statistical significance. Graphs were created with
either STATA or R (version 2.12.2: http://www.rproject.
The search strategy identified 99 papers eligible for
evaluation. After applying the inclusion and exclusion
criteria, 83 studies were excluded. Sixteen studies were
provisionally included for this systematic review
(Figure 1). Two studies in which the population was a
subpopulation from an original study, which was
already included for this review, were excluded for
evaluation (Wahlgren et al., 1997; Costa Lda et al.,
2009). The authors of 10 studies were contacted by mail
and email to get additional information on proportions
of patients with pain at 1 year and, if available, other
follow-up time points and the exact definition used for
being pain free (Faas et al., 1993; Weber et al., 1993;
Dettori et al., 1995; Klenerman et al., 1995; Croft et al.,
1998; Epping-Jordan et al., 1998; Burton et al., 1999;
Werneke and Hart, 2001; Karjalainen et al., 2003;
Grotle et al., 2007). This approach resulted in a total of
11 studies that were finally included for evaluation in
this review (Dettori et al., 1995; Klenerman et al.,
1995; Croft et al., 1998; Epping-Jordan et al., 1998;
Burton et al., 1999; Schiottz-Christensen et al., 1999;
McGuirk et al., 2001;Werneke and Hart, 2001; Sieben
et al., 2005; Bousema et al., 2007; Henschke et al.,
Characteristics of included studies
In Table 4, the characteristics of the 11 included
studies are shown. The number of participants in each
study varied between 83 and 973. The percentage of
male participants varied between 45% and 100%. The
outcome parameter that was considered of primary
interest varied largely between the evaluated studies
and included pain but also physical activity and function;
disability; fear avoidance; and sick leave. Two
studies were performed in the United States, two
studies in Australia and the remaining seven were
The anatomical definition of LBP was mostly
defined according to localization of the pain; in six
studies no definition was stated. The definition of LBP
differs between studies, one study defined LBP as pain
in the thoracic and lumbar region, other studies formulated
LBP as localized ‘between the scapulae and
the gluteal folds’, or ‘below thoracic vertebra 6 (T6)’,
or ‘between T12 and the buttock crease’.
Different methods and pain scales were used for the
evaluation of pain intensity, namely: Visual Analogue
Scale (VAS); Numeric Rating Scale; Graded Chronic
Pain Scale; and Descriptor Differential Scale; a selfconstructed
question about pain/a question about
pain specifically constructed for the study (Price et al.,
1983; Gracely and Kwilosz, 1988; Von Korff et al.,
1992; Childs et al., 2005).
Studies used different cut-off points for classifying
patients as free from pain and different periods in
which the patient had to be pain free (varying from 1
day to 6 months).
The mean time since onset of LBP varied between 0
and 12 weeks. In many studies, the timing of the
follow-up visits was at 1, 3, 6 and 12 months (Table 4).
Methodological quality varied between 40% and 90%
Clinical course of LBP
Figure 2 shows the course of acute LBP during follow-up
of 1 year according to the pooled proportions of
patients with pain at 1, 3, 6 and 12 months. These
pooled proportions at 1, 3 and 6 months after onset
were 80% (95% CI: 61–100%); 67% (95% CI:
50–83%) and 57% (95% CI: 46–68%), respectively.
The pooled proportion of patients with pain 1 year
after onset of LBP was 65% (95% CI: 54–75%).
The Forest plot (Figure 3) shows the proportions of
patients who still reported pain at 1 year after onset of
LBP with 95% CI for the individual 11 studies. The I2
index was 96.5 %, which indicates large heterogeneity
of study results.
There are five studies that reported proportions with
pain at both 3 and 12 months (Croft et al., 1998; Burton
et al., 1999; McGuirk et al., 2001; Sieben et al., 2005;
Henschke et al., 2008). All five studies showed that
after 3 months there was little additional recovery,
namely between 3 and 12 months the percentage of
patients still reporting pain decreased by only 1–7%.
Figure 4 shows the results of subgroup analyses with
respect to the effect of pre-specified study characteristics
on study results. The pooled proportion of patients
with pain at 1 year after onset was significantly lower
in two Australian studies than the pooled proportion
based on nine studies from Europe or the United
States. The pooled proportion of patients with pain at
1 year after onset was significantly lower for studies
that used a less stringent definition of recovery from
pain, i.e., studies that also considered patients who
reported mild pain as being free from pain and studies
that used a self-formulated question about pain/a
question about pain specifically formulated for the
study (Dworkin et al., 2005, 2009).
The findings of this review indicate that the majority
of patients (65%) still experience pain 1 year after
onset of LBP. In the first 3 months, recovery is
observed in a substantial part of the patients, but
thereafter only few patients recover.
The conclusion of this review is in line with a previous
systematic review that questioned the prognosis
of acute LBP and also found high rates of LBP after 1
year varying between 42% and 75% (Hestbaek et al.,
2003). This review differed from the present review by
also including studies that were performed in secondary and tertiary care settings and no restriction to
recent onset of acute LBP. Despite the differences, both
reviews arrive at similar results. This finding may indicate
that in the present review efforts to restrict the
study population to patients with early onset of back
pain have not been successful. The definition of recent
onset LBP is, with a duration of less than 3 months,
rather arbitrarily defined and relies heavily on the
memory of patients who may feel that their back pain
is of recent origin whereas it could have started more
than 3 months ago.
The findings in this review are in sharp contrast
with current recommendations and guidelines for the
treatment of patients with non-specific LBP, which
are based on the assumption that in a large majority
of patients spontaneous recovery occurs. The European
guidelines for acute non-specific LBP cite that
acute LBP is usually self-limiting (a recovery rate of
90% within 6 weeks) and only 2–7% of people
develop chronic pain, although references to underpin
this statement are not provided (van Tulder et al.,
2006). The assumption that spontaneous recovery is
common resulted in management recommendations
that put strong emphasis on reassurance of the
patient that rapid recovery is to be expected, limitation
of referral to secondary care and continuation of
It may be worth considering what may be the basis
for this widespread belief that spontaneous recovery is
common. One of the reasons may be that in many
studies on back pain published during the last 20
years, ‘return to work’ or ‘recovery from disability’
was considered evidence for recovery from LBP
(Spitzer et al., 1987; Andersson, 1999). However, this
supposition may be criticized as it is quite conceivable
that patients may still suffer from pain. Another
reason may be that individual studies show variation
in results, although none of the reviewed studies
reported a recovery rate of 80–90%.
Four larger studies that were included in this review
reported that the proportion of patients who are still
having pain 1 year after onset varied between 41% and
75%. Therefore, another aim of the present review was
to explore reasons for the large variation between
studies in pain results. An important source of heterogeneity
that was identified was the definition of pain
recovery that was used. The subgroup of studies that
considered total absence of pain as a criterion for recovery
and used a validated pain questionnaire, e.g., the
VAS, showed a higher pooled proportion of patients
with pain (71%) compared with the studies that used
less stringent standards and/or were content with considering
low pain scores as indicative of complete
recovery (57%). The difference in the pooled proportions
is 20% (Fig. 4).
Another interesting finding may be that studies performed
in Australia (McGuirk et al., 2001; Henschke
et al., 2008) reported more favourable prognosis than
the studies from Europe and the United States. The
pooled proportion of patients with pain at 12 months
was lower in Australian studies than in American/
European studies, with a difference of 27% (Fig. 4).
One explanation for this finding could be that the
American/European studies generally used a combination
of outcome measures regarding LBP. This is in
accordance with the IMMPACT recommendations by
Dworkin et al. who recommended use of a combination
of relevant validated outcome measures to evaluate
treatment effectiveness (Dworkin et al., 2005). In
the Australian study by McGuirk, only a VAS was used
and patients who reported mild pain, with one single
pain intensity score from 0 to 10 mm on a VAS from 0
to 100 mm, were considered as being free from pain.
The other Australian study by Henschke et al. used
only one modified question of the SF36 questionnaire
(Henschke et al., 2008) whereas the SF questionnaire
was not developed for this purpose.
The results of this and other systematic reviews indicate
that the current approach towards management
of patients with non-specific LBP calls for reorientation.
The paradigm that the prognosis of LBP is mostly
favourable can lead to conservatism in pain management
and could be contra-productive for innovations
in pain treatment. It may have paralysed the need for
knowledge about mechanism and causes of back pain
and hampered development of further treatment
There should be more focus on intensive follow-up
and monitoring of patients who have not recovered
from pain within 3 months. Pharmacologic treatment
and minimally invasive interventions must be
Further research is needed to re-evaluate the
concept of non-specific LBP. At present, LBP with
unknown cause is diagnosed as non-specific. But it
can not be excluded that within this heterogeneous
group identification of patients with specific causes is
possible. Classification into more specific subgroups
could result in more homogeneous groups and help
advance development of more pinpointed and specified
pain treatment options.
This review has some limitations. First, results are
based on published data with a large variation in
study results. To account for this heterogeneity, a
random-effects model was used, but such a metaanalytic
approach has limitations and therefore
results from pooling must be interpreted with
caution. However, if we had refrained from pooling,
the conclusion would still be that pain persists in a
substantial proportion of patients, as even studies
with conservative estimates indicate that at least
40% of patients are not free from pain after 1 year of
Second, for the evaluation of the course of LBP
over time, the pooled proportions at consecutive time
points were derived from different sets of studies.
There were only five studies that reported results at
both 3 and 12 months (Croft et al., 1998; Burton
et al., 1999; McGuirk et al., 2001; Sieben et al., 2005;
Henschke et al., 2008). The pooled proportions of
patients with pain from these studies were 67% (50–
83%) and 62% (44–81%) at 3 and 12 months,
respectively, and are consistent with the conclusion
that one-third of patients recover within the first 3
months and that the majority still report pain at 12
Third, this review provides information on prevalence of pain at longer follow-up, but not on severity of pain. Information on the distribution of pain scores in patients with persisting pain was not provided in detail by the included studies, only one study presented a mean VAS pain score of 26.5 mm in patients who still suffer pain at 12 months of follow-up (Bousema et al., 2007). It is recommended to address this issue in more detail in future studies on clinical course of patients with non-specific acute LBP.
This systematic review shows that spontaneous recovery from non-specific LBP occurs in the first 3 months after onset of LBP in about one-third of patients, but the majority of patients (65%) still experience pain 1 year after onset of LBP. These findings indicate that the assumption underlying current guidelines that spontaneous recovery occurs in a large majority of patients is not justified. There should be more focus on intensive follow-up and monitoring of patients who have not recovered within the first 3 months. Future research should be directed at improvement of classification of non-specific LBP in more specific groups.
Both C.I. and J.G. independently screened the titles,
abstracts and keywords of all references identified by the
literature search, extracted data from selected studies on
population and study characteristics, and assessed the quality
of the articles. J.G. corresponded with authors from studies
considered for evaluation. Analyses were performed by J.G.
and P.N. P.N. and M.v.K. oversaw and contributed to the
overall execution of the project. All authors discussed the
results and commented on the manuscript. All authors
helped to write the manuscript.
The authors like to thank Sander van Kuijk from the Department
of Epidemiology of the Maastricht University for
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Werneke, M., Hart, D.L. (2001).
Centralization phenomenon as a prognostic factor for chronic low back pain and disability.
Spine 26, 758–764; discussion 765.
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