Family Practice Vol. 17, No. 6, 554-556
© Oxford University Press 2000
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Does spinal manipulation have specific treatment effects?
Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, 25 Victoria Park Road, Exeter EX2 4NT, UK.
Ernst E. Does spinal manipulation have specific treatment effects? Family Practice 2000; 17: 554–556.
Received 17 January 2000; Accepted 17 July 2000.
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Abstract |
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Objective. To investigate the question whether or not spinal manipulation is associated with specific treatment effects.
Methods. Literature searches were carried out in Medline, Embase and The Cochrane Library. All sham-controlled trials of spinal manipulation were considered.
Results. Seven such studies were located. Their methodological quality was variable but three trials adhered to the highest standards of scientific rigour. Collectively these data do not show therapeutic effects beyond placebo. In particular, the three most rigorous studies were negative.
Conclusion. The few sham-controlled trials that do exist show that this methodology is, in principle, applicable also to spinal manipulation. The results available to date suggest that the therapeutic success of spinal manipulation is largely due to a placebo effect.
Keywords. Spinal manipulation, chiropractic, osteopathy, placebo effect, alternative medicine.
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Introduction |
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Chiropractic was founded in 1895 by Daniel David Palmer and is based on the belief that the nervous system is the most important determinant of a person’s state of health. Chiropractors believe that nerve interferences caused by spinal misalignments (‘subluxations’) are the underlying cause of ill health, and that correcting misalignments restores health. Spinal adjustments are achieved by spinal manipulation (SM) which involves high-velocity thrusts with either a long or short lever-arm.
The debate whether or not SM constitutes an efficacious treatment continues. A meta-analysis1 of randomized clinical trials arrived at a positive overall conclusion. However, the included trials did not differentiate between specific and non-specific effects of SM. The possibility of spontaneous or placebo-derived improvement in chronic illness dictates that efficacy trials be adequately controlled and blinded. Therefore, only sham-controlled, blinded trials (defined as studies in which the control intervention mimicked SM and both the patient and the evaluator were blinded) will tell us whether the clinical outcomes of SM are due to specific or non-specific (e.g. placebo) effects. Several trials exist which might answer this question.
Nineteen patients with chronic low back pain were randomized into one group receiving a standardized set of chiropractic adjustments or sham adjustments using minimal force.2 After 2 weeks of treatment, there was significant pain relief in the actively treated group. No such differences were noted in the sham group. Spinal mobility improved significantly in the actively treated group compared with the control group. Unfortunately these results may be unreliable since (i) a degree of ‘de-blinding’ was noticed; (ii) sample size was small; (iii) there was a substantial number (10) drop-outs; (iv) no intention-to-treat analysis was undertaken; and (v) the statistical comparisons regarding pain were within rather than between groups.
Forty-six children with primary nocturnal enuresis were randomized into two groups.3 One group received high-velocity, short-lever thrusts consistent with the ‘Palmer package adjusting technique’ while the control group received sham adjustments. At the end of the 10 week treatment period, significantly less bed-wetting was noted in the experimental group compared with the control group. Unfortunately, there was already a similar difference at baseline. The frequency of wet nights significantly decreased in the experimental group. However, the within-group changes showed no significant difference when compared between groups. The authors conclude that these results ‘strongly suggest the effectiveness of chiropractic treatment for primary nocturnal enuresis’,3 yet adequate statistical tests did not yield a statistically significant result.
Two hundred and nine consecutive patients with untreated chronic low back pain were randomized to either receive chiropractic, sham-chiropractic or back pain education. Chiropractic treatment consisted of high-velocity, low-amplitude SM. Sham treatment consisted of high-velocity, low-force mimic adjustments.4 At the end of the 2 week treatment period, the results of the Oswestry disability score significantly favoured the chiropractic treatment, while pain measurements failed to reach the level of statistical significance. The authors concluded that "there appears to be clinical value to treatment according to a defined plan using manipulation".4 This conclusion might be challenged on several grounds. For instance, a degree of de-blinding could have occurred. A high number of dropouts was noted—of the 209 patients only 117 cases could be included in the analysis of the Oswestry disability score—yet no intention-to-treat analysis was performed.
In a crossover study, 31 chronic asthma patients were randomized to receive either twice-weekly (for 4 weeks) chiropractic or sham treatments in addition to conventional treatments.5 Active treatment consisted of high-velocity, low-amplitude thrusts. Standard lung function tests, daily usage of medication, patient-rated asthma severity and non-specific bronchial reactivity had been defined as the main outcome variables. The results yielded no statistically significant or clinically relevant inter-group differences in any of these parameters. When patients were asked which treatment they preferred, 19 opted for the active and 10 for the sham therapy. The authors conclude that their results do not support the hypothesis that chiropractic treatment is superior to sham as a treatment for chronic asthma.
Eighteen college students suffering from phobias were exposed to a picture of the object of their phobia (e.g. a spider). Subsequently the treatment group received a short-lever SM. The force of the SM was ‘high’ in this group while the control group received a sham treatment with the instrument’s force set at zero. Following these interventions, participants were re-exposed to their phobogenic stimulus. The endpoints measured were pulse rate and subjective emotional response. Analyses of variance showed that there were no pre–post differences in heart rate but a significant decrease in emotional discomfort was reported in the experimental group.
Ninety-one children were randomized to receive either regular chiropractic or sham treatments for 16 weeks in addition to regular care.7 Active treatment consisted of SM deemed to be the optimal treatment for each individual. Sham treatments consisted of hands-on procedures without adjustments. Standard lung function tests, symptoms and usage of medication had beendefined as the main outcome variables. The results showed no differences between these groups in relation to any parameter. Patients were unable to distinguish ‘active’ from ‘sham’ therapy. The authors conclude that "chiropractic spinal manipulation provided no benefit for asthmatic children".6
One hundred and thirty-eight women suffering from primary dysmenorrhoea were randomized to receive either four cycles of SM (high-velocity, short-lever, low-amplitude thrusts) or sham treatment. The main outcome measurements were pain and a dysmenorrhoea symptom score. This study found no significant differences in response between the two groups.
Of all these seven sham-controlled trials, three stand out in terms of methodological quality.4,7,8 The results of these studies show no significant differences between sham treatment and real SM. This suggests that, in these particular settings, the therapeutic effects resulted from non-specific (e.g. placebo) effects and/or regression towards the mean. Interestingly, two of these studies relate to asthma4,7 and one to primary dysmenorrhoea.8 None refers to low back pain, which is by far the most important indication for SM. The two sham-controlled trials of low back pain2,3 were burdened with serious methodological flaws. An authoritative systematic review of all randomized (but not necessarily sham-controlled) trials also found "no convincing evidence of the effectiveness of chiropractic for acute or chronic low back pain".9 More recent non-sham-controlled trials produced mixed results. Two10,11 failed to demonstrate that SM is more effective for low back pain than physiotherapy. Other such studies (e.g. references 12 and 13) yielded ambiguous results. Conclusions regarding the specific efficacy of SM for low back pain, therefore, must await adequately designed sham-controlled trials.
If the mechanism of action were that of a (powerful) placebo, SM might still be useful in clinical practice. Neither the patient nor the therapist is usually critically concerned about mechanisms of action as long as there is clinical improvement. This argument is applicable if the therapy under discussion is not associated with considerable risks. In the trials reviewed above, adverse effects were not mentioned in the weaker studies,2,3,4 while Nielsen et al.5 explicitly stated that no adverse events occurred, Balon et al.7 only noted exacerbation of asthma symptoms and Hondras et al.8 found some minor soreness at the site of SM. Two large prospective investigations of adverse effects suggest that mild, transient adverse effects (mostly local or referred pain) occur in about half of all cases.14,15 Serious complications of SM seem to be very rare. They include vertebral artery dissection (upper spinal manipulation) and canda equina syndrome (lower spinal manipulation).16,17 At present the incidence of such serious adverse events can only be estimated.
In conclusion, the few sham-controlled trials of SM available at present do not support the hypothesis that SM is associated with specific therapeutic effects. Further research into this area seems warranted.
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References |
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1 Shekelle PG, Adams AH, Chassin MR, Hurwitz EL, Brook RH. Spinal manipulation for low back pain. Ann Intern Med 1992; 117: 590–598.
2 Waagen GN, Haldeman S, Cook G, Lopez D, DeBoer KF. Short term trial of chiropractic adjustments for the relief of chronic low back pain. Manual Med 1986; 2: 63–67.
3 Reed WR, Beavers S, Reddy SK, Kern G. Chiropractic management of primary nocturnal enuresis. J Manip Physiol Ther 1994; 17: 596–600.[ISI][Medline]
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5 Nielsen NH, Bronfort G, Bendix T, Madsen F, Weeke B. Chronic asthma and chiropractic spinal manipulation: a randomized clinical trial. Clin Exp Allergy 1995; 25: 80–88.[ISI][Medline]
6 Peterson KB. The effects of spinal manipulation on the intensity of emotional arousal in phobic subjects exposed to a threat stimulus: a randomized, controlled, double-blind clinical trial. J Manip Physiol Ther 1997; 20: 602–606.[ISI][Medline]
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Balon J, Aker PD, Crowther ER et al. A comparison of active and simulated chiropractic manipulation as adjunctive treatment for childhood asthma. N Engl J Med 1998; 339: 1013–1020.
8 Hondras MA, Long CR, Brennan PC. Spinal manipulative therapy versus a low force mimic manoeuvre for women with primary dysmenorrhea: a randomized, observer-blinded, clinical trial. Pain 1999; 81: 105–114.[ISI][Medline]
9 Assendelft WJJ, Koes BW, van der Heijden GJMG, Bouter L. The effectiveness of chiropractic for treatment of low back pain: an update and attempt at statistical pooling. J Ther Physiol Ther 1996; 19: 499–507.
10 Skargren EI, Öberg BE. Predative factors for 1-year outcome of low-back and neck pain in patients treated in primary care: comparison between the treatment strategies chiropractic and physiotherapy. Pain 1998; 77: 201–207.[ISI][Medline]
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Cherkin DC, Deyo RA, Battie M, Street J, Barlow W. A comparison of physical therapy, chiropractic manipulation, and provision of an educational booklet for the treatment of patients with low back pain. N Engl J Med 1998; 339: 1021–1029.
12 Meade TW, Dyer S, Browne W, Townsend J, Frank AO. Low back pain of mechanical origin: randomised comparison of chiropractic and hospital outpatient treatment. Br Med J 1990; 300: 1431–1437.
13 Rasmussen GG. Manipulation in treatment of low back pain: a randomized clinical trial. Manual Med 1979; 1: 8–10.
14 Leboeff-Yde C, Hennius B, Rudberg E, Leufvenmark P, Thunman M. Side effects of chiropractic treatment: a prospective study. J Manip Physiol Ther 1997; 20: 511–515.[Medline]
15 Senstad O, Leboeuf-Yde C, Borchgrevink C. Frequency and characteristics of side effects of spinal manipulative therapy. Spine 1997; 22: 435–441.[ISI][Medline]
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Di Fabio RP. Manipulation of the cervical spine: risks and benefits. Phys Ther 1999; 79: 50–65.
17 Assendelft WJJ, Bouter LM, Knipschild PG. Complications of spinal manipulation a comprehensive review of the literature. J Fam Pract 1996; 42: 475–480.[ISI][Medline]
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