Rapid Responses to:
|
|
Rapid Responses: Rapid Responses published:
-
![[Read Rapid Response]](/icons/misc/sectionDOWN.gif)
Systematic review of prognosis in acute low back pain: danger of high publication bias
- Michal R Pijak, Frantisek Gazdik (9 August 2003)
-
Re: Systematic review of prognosis in acute low back pain: danger of high publication bias
- Rob D Herbert, Pengel LHM, Maher CG, Refshauge KM. (11 August 2003)
-
Re:Re: Systematic review of prognosis in acute low back pain: danger of high publication bias
- Michal R Pijak, Frantisek Gazdik (12 August 2003)
-
Acute low back pain: early intervention to reduce chronicity
- Ash Samanta, Jo Samanta, Julia Kendall (18 August 2003)
-
Recurance of low back pain
- Michael Norberg (18 August 2003)
-
Re: Re:Re: Systematic review of prognosis in acute low back pain: danger of high publication bias
- Rob D Herbert, Liset HM Pengel, Chris G Maher, Kathy M Refshauge (19 August 2003)
-
Low back pain should be viewed as a chronic disease
- Michal R Pijak, Frantisek Gazdik (20 August 2003)
-
Systematic review of prognosis in acute low back pain: bias in indentification of relevant studies
- Michal R Pijak, Frantisek Gazdik (27 August 2003)
-
Bias in review of back pain prognosis
- Jos H Verbeek (11 September 2003)
-
RE: Bias in review of back pain prognosis
- Liset HM Pengel, Rob D Herbert, Chris G Maher, Kathryn M Refshauge (14 October 2003)
|
|
|||
|
Michal R Pijak, Consultant in rheumatology and clinical immunology Institute of Preventive and Clinical Medicine, Limbova 14, 83301, Bratislava, Slovakia, Frantisek Gazdik
Send response to journal:
|
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 |
|||
|
|
|||
|
Rob D Herbert, senior lecturer School of Physiotherapy, University of Sydney, PO Box 170, Lidcombe NSW 1825, Australia, Pengel LHM, Maher CG, Refshauge KM.
Send response to journal:
|
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 |
|||
|
|
|||
|
Michal R Pijak, Consultant in rheumatology and clinical immunology Institute of Preventive and Clinical Medicine, Limbova 14, 83301, Bratislava, Slovakia, Frantisek Gazdik
Send response to journal:
|
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 |
|||
|
|
|||
|
Ash Samanta, consultant rheumatologist Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust LE1 5WW, Jo Samanta, Julia Kendall
Send response to journal:
|
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 |
|||
|
|
|||
|
Michael Norberg, Spine unit Centre thermal 1892 Lavey-les-Bains; Hopital orthopédique, 1005 Lausanne
Send response to journal:
|
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 |
|||
|
|
|||
|
Rob D Herbert, senior lecturer School of Physiotherapy, University of Sydney, PO Box 170, Lidcombe NSW 1825, Australia, Liset HM Pengel, Chris G Maher, Kathy M Refshauge
Send response to journal:
|
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 or 2-3 weeks. 73% of subjects with pain of less than 3 weeks at first consultation reported pain and/or disability at 3 months and 64% reported pain and/or disability at 12 months (calculated from Table 5). This is consistent with our conclusion that pain and disability typically persist for long periods and it suggests that the low average levels of pain and disability are due to low levels of pain and disability in a large proportion of patients. 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 |
|||
|
|
|||
|
Michal R Pijak, Consultant in rheumatology and clinical immunology Institute of Preventive and Clinical Medicine, Frantisek Gazdik
Send response to journal:
|
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 |
|||
|
|
|||
|
Michal R Pijak, Consultant in rheumatology and clinical immunology Institute of Preventive and Clinical Medicine, Limbova 14, 83301 Bratislava, Slovakia, Frantisek Gazdik
Send response to journal:
|
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 |
|||
|
|
|||
|
Jos H Verbeek, senior lecturer occupational health Academic Medical Center, 1105 AZ Amsterdam
Send response to journal:
|
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 |
|||
|
|
|||
|
Liset HM Pengel, PhD student School of Physiotherapy, University of Sydney, PO BOX 170, Lidcombe NSW 1825, Australia, Rob D Herbert, Chris G Maher, Kathryn M Refshauge
Send response to journal:
|
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 |
|||