British Medical Journal 2008 (Jul 7); 337: a171 ~ FULL TEXT
Henschke N, Maher CG, Refshauge KM, Herbert RD, Cumming RG, Bleasel J, York J, Das A, McAuley JH.
Musculoskeletal Division, The George Institute for International Health, Sydney, Australia.
This study contradicts Clinical Practice Guidelines that suggest that recovery from an episode of recent onset low back pain is usually rapid and complete. Their findings with 973 consecutive primary care patients was that recovery was slow for most patients, and almost 1/3 of patients did not recover within one year (when following standard medical recommendations). This study was designed to determine the one year prognosis of patients with low back pain. 973 patients with low back pain that had lasted less than 2 weeks completed a baseline questionnaire. Patients were reassessed through a phone interview at six weeks, three months and 12 months. The study found that the prognosis claimed in clinical guidelines was more favorable than the actual prognosis for the patients in the study. Recovery was slow for most patients and almost 1/3 of patients did not recover within one year.
OBJECTIVE: To estimate the one year prognosis and identify prognostic factors in cases of recent onset low back pain managed in primary care.
DESIGN: Cohort study with one year follow-up.
SETTING: Primary care clinics in Sydney, Australia.
PARTICIPANTS: An inception cohort of 973 consecutive primary care patients (mean age 43.3, 54.8% men) with non-specific low back pain of less than two weeks' duration recruited from the clinics of 170 general practitioners, physiotherapists, and chiropractors.
MAIN OUTCOME MEASURES: Participants completed a baseline questionnaire and were contacted six weeks, three months, and 12 months after the initial consultation. Recovery was assessed in terms of return to work, return to function, and resolution of pain. The association between potential prognostic factors and time to recovery was modelled with Cox regression.
RESULTS: The follow-up rate over the 12 months was more than 97%. Half of those who reduced their work status at baseline had returned to previous work status within 14 days (95% confidence interval 11 to 17 days) and 83% had returned to previous work status by three months. Disability (median recovery time 31 days, 25 to 37 days) and pain (median 58 days, 52 to 63 days) took much longer to resolve. Only 72% of participants had completely recovered 12 months after the baseline consultation. Older age, compensation cases, higher pain intensity, longer duration of low back pain before consultation, more days of reduced activity because of lower back pain before consultation, feelings of depression, and a perceived risk of persistence were each associated with a longer time to recovery.
CONCLUSIONS: In this cohort of patients with acute low back pain in primary care, prognosis was not as favourable as claimed in clinical practice guidelines. Recovery was slow for most patients. Nearly a third of patients did not recover from the presenting episode within a year.
From the FULL TEXT Article
In this study of 12 month prognosis in patients with recent onset low back pain, recovery was typically much slower than previously reported. Nearly a third of patients did not recover from the presenting episode within a year. Return to work and recovery from disability and pain did not occur synchronously. We identified seven readily assessed factors that were associated with speed of recovery and can be considered by clinicians when advising their patients about the prognosis for their episode of acute low back pain.
Strengths and weaknesses
The strengths of our study are that we enrolled an inception cohort from the three main primary care providers who manage low back pain and measured pain, disability, and work status over a 12 month period with high rates of follow-up. Our previous review of prognostic studies of low back pain found that few studies of acute low back pain have achieved these benchmarks.  A limitation of the study is that socioeconomically disadvantaged people were under-represented in the cohort. There are many health conditions where socioeconomic disadvantage has been linked to poor outcome, and if this applies to low back pain it might be that we have produced an overly optimistic view of prognosis. Another limitation is that we did not record participantsí occupation so we were unable to assess whether this factor influenced the speed with which people returned to work.
Comparison with other research
There are only a few methodologically sound prognosis studies that have followed patients beyond three months.  Schiottz-Christensen et al enrolled 524 patients from Danish primary care whose pain had lasted less than two weeks and found that recovery was slow and incomplete.  Complete recovery was 41% by one month, 44% by six months, and 54% by 12 months; results quite similar to our six week, three month, and 12 month figures of 39%, 57%, and 72%. In contrast, Coste et al reported that recovery was rapid.  They reported that 90% of their cohort had recovered by two weeks whereas in our study only 23% had recovered by two weeks and in the study of Schiottz-Christensen et al only 41% had recovered by four weeks (recovery data for two weeks are not reported). Coste et al enrolled 103 patients from French primary care and, unlike in our study and that of Schiottz-Christensen et al, used a cut-off of 72 hours to define an inception cohort.  To test the effect of Coste et alís stricter criterion, we repeated our survival analysis on the subset of participants (n=530) whose back pain had lasted for up to three days but found the recovery rate virtually unchanged at two weeks. Accordingly, we are unable to explain the marked difference in results.
There are difficulties comparing prognostic factors between our study and those of Coste et al  and Schiottz-Christensen et al  because there was not a common set of predictors, the studies used different approaches to building a prognostic model, and with 103,  524,  and 969 participants had quite different statistical power to detect prognostic associations. None the less, there are some common findings. All three studies report that low back pain in compensation cases and high disability at baseline were adverse prognostic factors, and our study and the study by Coste et al  report that a previous episode of low back pain was an adverse prognostic factor. In common with our study, Schiottz-Christensen et al reported that perceived risk of persistence was an adverse prognostic factor,  but in that study the clinician judged risk of persistence whereas in our study this judgment was made by the patient.
Implications for the guidelines
Our findings support the recommendations in clinical practice guidelines that clinicians should screen for adverse prognostic factors (yellow flags). We identified seven factors associated with poor prognosis that could be readily applied in primary care. These results also concur with the view that psychosocial factors are important factors predicting poor outcome. In contrast to most guidelines we found that recovery from low back pain is typically slow and incomplete. The slow and incomplete recovery occurred even though we trained all clinicians in the study to provide best practice care consistent with current clinical guidelines. At the moment it is unclear how better health outcomes can be achieved. Establishing whether it is the endorsed treatments or their implementation that is the problem could help to improve outcomes for acute low back pain.
Recovery did not occur synchronously in the three dimensions of return to work, interference with function, and pain status. Most patients who reduced their work status as a result of their low back pain resumed their pre-back pain work status quickly, but this was not indicative of recovery from an episode of low back pain. The return to pre-injury work hours and duties occurred more quickly and in more participants than recovery from pain or interference with function. Of the three dimensions used to measure recovery, pain took the longest to resolve. In fact the survival curves for recovery from pain and complete recovery were similar. This indicates that the primary impediment to complete recovery is ongoing pain. Nearly a third of the participants had not recovered from the initial episode by 12 months.
Despite widespread investigation, there has been little consensus regarding predictors of outcome from acute low back pain. [12, 25] Rather than testing the predictive value of large numbers of individual variables, as is common practice, we grouped potential predictive variables into discrete factors, controlling for demographic and pain related covariates. While the factors might not have been able to fully describe complex constructs such as culture and psychology, factor items were taken from validated questionnaires. [17, 25, 26] Using this approach we identified seven variables that were independently associated with poor prognosis. Psychological characteristics (feelings of depression and perceived risk of persistence) were most closely associated with time to recovery, while characteristics of the current history (low back pain in compensation cases and duration of episode) were still significantly associated with time to recovery after we accounted for psychological characteristics.
The most obvious use of prognostic information is to provide patient specific estimates of prognosis to individual patients in primary care. The prognostic factors we identified are readily assessed in primary care. That treatment should be targeted towards factors that have an adverse effect on recovery,  and our findings provide some insight into how this might be achieved in primary care. For example, as compensation status was the strongest predictor, it might be worth investigating the process of care for a cohort of patients in compensation cases to identify potential causes of delayed recovery. In addition, our findings suggest that effective strategies could be investigated for the assessment and management of symptoms of depression and catastrophising. Further studies are warranted to evaluate the validity of these predictors in other cohorts of patients with acute low back pain in primary care.
What is already known on this topic
Clinical practice guidelines suggest that recovery from an episode of recent onset low back pain is usually rapid and complete
Recent systematic reviews suggest that the risk of developing chronic low back pain is uncertain
What this study adds
In this cohort of patients, recovery from recent onset low back pain was much slower than has been reported and nearly a third did not recover within a year
Older age, back pain associated with compensation cases, higher pain intensity, longer duration of low back pain before consultation, more days of reduced activity because of low back pain before consultation, feelings of depression, and a perceived risk of persistence were all associated with poorer prognosis
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