A review of the treatment of chronic low back pain with acupuncture-like transcutaneous electrical nerve stimulation and transcutaneous electrical nerve stimulation

Complementary Therapies in Medicine (1997)5, 193-201

© HarcourtBrace& Co Ltd 1998

A review of the treatment of chronic low back pain with acupuncture-like transcutaneous electrical nerve stimulation and transcutaneous electrical nerve stimulation M. W. Flowerdew, J. G. G a d s b y Beccles Acupuncture Clinic, Beccles, Suffolk, UK SUMMARY. A meta-analysis of published studies was carried out to evaluate the effectiveness of acupuncturelike transcutaneous electrical nerve stimulation (ALTENS) and transcutaneous electrical nerve stimulation (TENS) in controlling pain and improving function in patients with chronic low back pain. Studies in English were identified by searches of EMBASE, MEDLINE, CISCOM and AMED. Other studies were located by citation tracking, searching by hand bibliographies and conference reports, and direct contact with subject experts. Studies were included in the meta-analysis if they were randomized controlled trials comparing ALTENS or TENS with a credible placebo in patients with low back pain of more than 8 weeks duration. Two reviewers extracted data on reduction in pain, changes in range of movement and functional status as well as determining the power of the included studies. Sixty-eight studies were initially identified, of which six (two using ALTENS and four using TENS) involving a total of 288 patients with mixed low back pathologies met the inclusion criteria for meta-analysis. The odds ratio (OR) of improvement in pain was calculated: ALTENS/TENS vs placebo OR = 2.1 (95% CI 1.3-3.4) ALTENS vs placebo OR = 7.2 (95% CI 2.6-20.1), TENS vs placebo OR = 1.5 (95% CI 0.9-2.6). OR for range of motion (ROM) on ALTENS vs placebo was 6.6 (95% CI 2.4-18.6). There were insufficient data to assess the effect of TENS alone on ROM, functional status and return to work. Similarly there were not enough data to assess ALTENS and functional status and return to work. There is limited statistical evidence that ALTENS and TENS reduce pain and improve function in patients with chronic low back pain, at least in the short term. This review and analysis is severely restricted by the lack of quality, randomized controlled trials. Even 25 years since the introduction of these treatments, powerful randomized controlled studies on the most appropriate use of TENS/ALTENS for the management of chronic low back pain have yet to be produced.

myofascial pain, iliolumbar ligament syndrome, sacroiliac dysfunction, lumbar misalignment and multifidus syndrome? The National Back Pain Association UK also includes muscle spasm, prolapsed intervertebral discs, spinal stenosis, ankylosing spondylitis, facet joint degeneration, spondylosis, 'failed back syndrome', osteochondritis and degenerative disc diseases. Sweetman et aP have recently tried to rationalize the common patterns into seven categories with associated diagnostic tests. However it is described, chronic back pain should not be regarded as longer episodes of acute back pain? Given the socioeconomic importance of low back pain, it is important to find a treatment that is effective. Early rehabilitation and return to work is important, but strategies for retuming patients to optimum levels of functioning as soon as possible have remained a challenge for the many practitioners treating musculoskeletal problems. 6,7 A number of treatments are usually utilized simultaneously for patients with chronic low back pain, but few of these combinations have been subjected to rigorous clinical evaluation. The

INTRODUCTION In the UK, about 70% of the adult working population suffer from at least one episode of back pain throughout their working lives. Although around 90% of cases resolve themselves naturally within 6 weeks) back pain accounts for 13% of certificated sickness leave in the UK, with estimated indirect costs to the country of £5 billion and a direct cost to the National Health Service of £480 million. 2In the primary sector, chronic low back pain is commonly presented, accounting for an estimated 14 million general practitioner consultations during 19952 and also represents a considerable source of referrals to orthopaedic and other departments in the secondary sector. Diagnosis and nomenclature remain a conundrum, the name used often reflecting the background, training and speciality of the practitioner involved, including lumbar sprain or strain, lumbago, M. W. Flowerdew, J. G. Gadsby, Beccles Acupuncture Clinic, 42 Station Road, Beccles, Suffolk NR34 9Q J, UK. Correspondence to M. W. Flowerdew. 193

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number of simultaneous treatments perhaps reflects the difficulties in diagnosing low back problems. One method that has undergone an extensive growth over the last 25 years is transcutaneous electrical nerve stimulation (TENS). TENS treatments can be divided into two basic types: conventional, high frequency, low intensity TENS and acupuncturelike transcutaneous electrical nerve stimulation (ALTENS), where the stimulation used is at low frequency but at high intensity. Conventional TENS uses a high rate, narrow pulse and moderate stimulation with parameter adjustments for rate between 50 and 200 Hz, a low pulse width of around 80 gs and an intensity raised to the level of comfort. ALTENS, also known as strong low rate (SLR) TENS, has electrical parameters adjusted to provide a low rate (14 Hz), a wide pulse width between 150 and 250 gs and an intensity at as high a level as can be tolerated by individual patients. 5,8,9Conventional TENS appears to produce rapid pain relief due to presynaptic inhibition of pain messages1° with release of GABA by large fibres throughout stimulation. This response usually ends on termination of treatment. It is thought that ALTENS produces enduring pain relief by pre- and post-synaptic control because of the release of endorphin with evidence of an accumulative effect over time. H,12 The TENS literature has been subjected to extensive narrative review.13-15Over 20 years ago, it was suggested that TENS was potentially important in the management of acute and chronic pain) 3 Since then, over 600 publications have supported the clinical efficacy of TENS and allied electrical therapies 16and for chronic back pain specifically, a review of published work has suggested 50% pain relief. ~5Other trials and reviews have refuted this degree of effectiveness for chronic low back pain, 17,~" and a Canadian Health Technology Assessment has concluded that TENS has not undergone sufficiently rigorous clinical evaluation and that few published reports meet acceptable standards? 9 The Canadian assessment is an overview of TENS applications generally and includes only 10 studies involving low back pain. In view of the number of conflicting studies and reviews of the efficacy of ALTENS and TENS in the treatment of chronic low back pain, it was decided to undertake a systematic review and meta-analysis, within the framework of the Cochrane Collaboration, of published data on this therapy for an incapacity that has such wide social and economic implications. This paper is based on work first published on the Cochrane Library in 1997. 20 The object of the study was to determine the effectiveness of ALTENS and TENS in reducing pain, improving range of movement (ROM) and function with patients with chronic low back pain so that practitioners and patients can make a more informed choice about the use of this increasingly popular therapy.

METHODS

It was decided to test the following comparisons in patients with chronic low back pain: 1. TENS treatment vs placebo for pain reduction 2. ALTENS treatment vs placebo for pain reduction 3. ALTENS/TENS vs placebo for pain reduction 4. TENS vs placebo for improving ROM 5. ALTENS vs placebo for improving ROM 6. ALTENS/TENS vs placebo for improving ROM 7. TENS vs placebo for improving function and return to work 8. ALTENS vs placebo for improving function and return to work 9. ALTENS/TENS vs placebo for improving function and return to work 10. ALTENS/TENS vs placebo with respect to sideeffects from treatment. Criteria for including studies in the review were: 1. Patients. Either sex with chronic low back pain, irrespective of specific diagnosis but with a history of at least 8 weeks. There is no standard definition of chronicity. The inclusion criterion for chronicity in this review was based on the evidence of CSAG 21which suggests that treatment in the first 6 weeks is vital to prevent the onset of chronicity and that 90% of patients will have recovered by this time. The conventional low back pain classification of <6 weeks for acute, <12 weeks for subacute and > 12 weeks for chronic ignores the dynamic nature of this problem, and most researchers define non-specific low back pain by duration of pain. 18,=Studies were excluded if they reported on acute (<6 weeks) or mixed acute and chronic patients. 2. Therapy. Electrical treatments using high frequency, low intensity TENS or low frequency, high intensity ALTENS vs a credible placebo. The electrical parameters differentiating the two types of therapy are fully described in Mannheimer & Lampe?4The credibility of the placebo rests on the similarity of the placebo and active treatments and can pose significant difficulties for therapies involving tactile stimuli. However, the use of what appears to be a fully functioning TENS unit with flashing LEDs, etc., but with no electrical output to the electrodes, rather than just a dead battery placebo, would appear to be the ideal. Patients receiving sham therapy should also receive visit frequency, contact and support equivalent to that in the active therapy condition25 3. Studies. Randomized, controlled comparisons of ALTENS or TENS vs credible placebo in the rehabilitation of patients with chronic low back pain. 4. Outcome measures. At least one outcome measure assessed using a suitable clinical intensity scale:

A review of the treatment of chronic low back pain with acupuncture (a) Effectiveness assessed in terms of overall improvement in pain measured by a suitable clinical pain intensity scale26 (b) Improved ROM using a validated procedure, e.g. straight-leg raise, spinal and hip flexion, Schober's spinal flexion assessment 27 (c) Assessment of functional status and well-being, 28 e.g. the modified Sickness Impact Profile for low back pain 29 (d) Early, gradual controlled return to work for those where no objective cause of pain could be found ~ (e) Follow-up assessments of pain and improvement in activity (f) Assessment of any side-effects. An improvement was recorded where total or partial pain relief was reported or increased activity recorded. Conversely, non-improvement was recorded if there was no pain relief or improved ROM at the end of the treatment period and at follow-up. Improvement in function was assessed using a validated method and return to work. Rules for assessing the quality of studies were agreed by the authors during the protocol development stage and before knowing the quality of the studies under review. Papers identified for consideration in the review and meta-analysis were sought in a number of ways: 1. Keyword searches of MEDLINE (1966 to October 1996), EMBASE (1985 to September 1995), AMED and CISCOM (to January 1995) and conversations with colleagues who have compiled their own databases, e.g. the Physical Therapy and Rehabilitation Field of the Cochrane Collaboration, University of Limberg, identified all studies in English on electrostimulation. Terms and expressions used were transcutaneous electrical nerve stimulation, transcutaneous electrical stimulation, acupuncture-like transcutaneous electrical nerve stimulation, transcutaneous electrical neurostimulation, transdermal electrical stimulation, electroacupuncture, peripheral conditioning stimulation, percutaneous neural stimulation, microamperage electrical stimulation, cranial electrotherapy stimulation, transcutaneous cranial electrical stimulation and transabdominal neurostimulation. Studies involving low back pain were then searched by hand and assessed against the criteria for inclusion in the review. 2. Hand-searching reference lists of these studies and citation tracking to find any studies missed in the computer searches. 3. Hand-searching books on TENS, physical therapies and electroacupuncture. 4. Searching abstracts of conferences on pain. 5. Correspondence with major researchers using ALTENS and TENS. 6. Narrative review articles and their references lists.

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All randomized controlled trials that did not compare ALTENS and/or TENS with a credible placebo and/or failed to conform with the electrical parameters for frequency and intensity were excluded from the review. The initial searches produced 68 papers which the authors, as reviewers, evaluated independently. Following the guidelines of Blair, 3°the authors and their institutions as well as publication journals were known to the reviewers, as blinding would have made it impossible to identify multiple publications of the same work. The reliability of inclusion/exclusion criteria was tested by reviewing three studies which were also used to clarify the systems for collecting data using Vickers' guidelines. 3I The quality of the methodology of these 68 studies was first rated using the Cochrane Collaboration guidelines 32and the following criteria: 1. Adequate treatment allocation concealment was assessed on a three-point scale: A, B or C (A: adequate, B: unclear, C: inadequate) 2. Blinding: was the study described as double-blind considering the difficulties in double-blinding a tactile treatment? 3. Were the control/placebo interventions credible? 4. Were the pain and/or activity assessments valid? 5. Were the numbers of withdrawals from the trial identified and handled appropriately? e.g. listed by diagnosis, treatment, precipitated by patient or practitioner. Different kinds of withdrawal could bias the final composition of the study group, diminishing the efficacy of the randomization procedure. Of these 68 studies, six met the inclusion criteria for the meta-analysis. The methodology and data of a further 40 studies, which had been included in other reviews, were assessed in more detail. These studies did not meet inclusion criteria for this review, although some had been included in other reviews. The remaining 22 were descriptive with no critical analysis of data. The 62 excluded studies are listed in the Appendix. Disagreement about inclusion or exclusion of individual studies was resolved by discussion between the reviewers. J.G.G. coordinated and sought extra information from authors, if necessary, on all randomized, controlled trials meeting the inclusion criteria. Analysis included all subjects who completed the trials and study groups where the randomization procedure had not been jeopardized by withdrawals. Data on the study populations, interventions, outcomes, assessments, side-effects by allocated treatment group and study quality measures were extracted using a previously agreed reviewers' checklist. The competence of the practitioners can affect an outcome, and trials should include a summary of the training and experience of the practitioners taking part as well as an indication as to whether of not the treatment under investigation is like that used in everyday practiceY These factors contribute to the

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model validity of each trial and were included as part of the assessment. The six trials meeting the inclusion criteria each used a different clinical scoring system for measuring outcome. Most recorded the numbers showing improvement in outcome; others recorded changes in the mean scores of rated outcome. We used numbers showing a clinical improvement in an outcome, and where mean scores had been recorded, they were converted to this mode. The typical odds ratio, a weighted estimate of the typical effect recorded across the six studies (i.e. the ratio of odds of a favourable outcome in the treatment allocated subjects to the corresponding odds in the control group) was calculated using the standard fixed-effects method of Peto with respective 95% confidence limits. The odds ratio was chosen according to Cochrane Collaboration guidelines using Metaview software. Trials without a dichotomized outcome for pain were converted to this mode using a method based on the outcomes of improvement vs no improvement. Means were not converted to odds ratios. Heterogeneity between trial results was tested using a standard Z2 test with n -1 degrees of freedom where n = number of trials. The quality of the six included trials was further examined using the Reeve et al Quality Rating Scale for randomized trials? 9This scale was initially used in a technology assessment of TENS by the Canadian Coordinating Office for Health Assessment, conceived by Chalmers et a133and modified by Reeve et al. Scores range from 0 to a maximum of 60.

RESULTS The six studies meeting the inclusion criteria for this review and meta-analysis consisted of two using ALTENS, three using TENS and one mixed frequency study 34-39(Table 1). 1. Thorsteinsson et al (1977)34: a randomized, crossover, control study of TENS (n = 33) vs placebo (n = 33), described as double-blind. Good description of subjects, inclusion criteria, treatment and its administration, blinding of randomization and practitioners. Shortcomings: the difficulty in blinding subjects to treatment, especially after crossover, with no washout period and only 3 days treatment before outcome evaluation; no exclusion criteria described; no a priori consideration of numbers for the study; only partial evaluation of randomization, blinding and outcome measures. No details of withdrawals and their handling given. Quality index 0.71. 2. Jeans (1979)3s: a randomized controlled trial of TENS (n = 6) vs placebo (n = 4). Treatment, procedures and patient blinding were well described. Shortcomings: only partial description

of inclusion criteria; partial blinding of randomization and practitioners; no a priori consideration of numbers entering the trial; partial evaluation of blinding and randomization; partial measures of outcome. Quality index 0.55. 3. Melzack et al (1983)36: This study was described as a double-blind investigation of TENS, but stimulation frequency was in the ALTENS range. ALTENS n= 20 vs placebo n = 21. Patients, treatment and its administration, inclusion criteria, blinding of randomization, a priori consideration of number of subjects and outcome measures were all well described. Shortcomings: adequacy of the placebo, mechanical massage treatment and limited capacity to blind subjects to treatment; partial description of inclusion/exclusion criteria; a range of ALTENS units and treatments used; practitioners not blinded; pain relief measured only at end of treatment with no follow-up; partial evaluation of randomization and blinding; no details of withdrawals and handling given. Quality index 0.70. 4. Deyo et al (1990)37: Not described as double-blind, but was a randomized, controlled trial of TENS or ALTENS. TENS/ALTENS n = 31, placebo n = 31. Description of subjects, inclusion/exclusion criteria, withdrawals and their management, treatment and its administration, blinding and evaluation of randomization, blinding of patients, evaluation of outcome were all well described and implemented. Shortcomings: subjects recruited by advert and heavily screened before entry into the trial; not all practitioners were blinded; adequacy of blinding only partially evaluated; no a priori consideration of number of subjects; TENS was not standardized; too many groups and variables, e.g. exercise, use of heating pads at home, caused difficulty evaluating the efficacy of the TENS and placebo treatments; an assumption that heat treatment has same effect on all subjects not verified; pain measured for short time only and considered over time and context; high withdrawal rate but was handled satisfactorily; the comparison of TENS vs sham TENS groups not well matched, containing unequal numbers of post-surgery patients (n = 19 and n = 10, respectively), but pooling four groups into two decreased this difference to n = 22 and n = 20, thereby adjusting for baseline differences. Quality index 0.84. 5. Gemignani et al (1991)38: randomized trial of ALTENS (n = 10) vs placebo (n = 10). Subjects, inclusion criteria, treatment and implementation, blinding of randomization, outcome measures well described. Shortcomings: no exclusion criteria; partial blinding of subjects and practitioners; no a priori estimation of subject numbers; adequacy of randomization and blinding not evaluated. Quality index 0.55.

A review of the treatment of chronic low back pain with acupuncture Table 1

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Characteristics of the studies included in the meta-analysis

Study

Diagnoses

Intervention

Outcomes

Quality rating

Thorsteinsson et al (1977) 3~

Mainly post-surgery; some arthritis

TENS at 15-180 Hz vs placebo, crossover, variable output/frequency x 20 min x 3 treatments with electrodes placed over predetermined sites Best results with electrodes over site of pain n = 33 treatment; n = 33 placebo

0.71 Low model validity: too many variables Randomized, crossover, controlled, double-blind?

Jeans (1979) 35

Non-specific low back pain

TENS at 60 Hz vs dead machine placebo, x 2 per day for 8 treatments Electrodes over pain, distal trigger/ acupuncture points, sham points n = 6 TENS; n = 4 dead machine

Valid outcome data and statistics reports of side-effects Initial outcome at 3 days 48.7% improved on TENS, 32.3% on control Follow-up questionnaire at 3 and 6 months No withdrawals Side-effects as allergic reaction and/or increase in pain x 5 Valid outcome measure of pain At 4 days, 40% reduction with TENS at local site,10% for control Some follow-up No withdrawals recorded No side-effects recorded Valid measures for pain and activity ALTENS more effective for pain relief and increasing ROM At 5 weeks ALTENS group 85% improved, massage 38% improved No follow-up No withdrawals recorded No side-effects recorded

0.70 Adequate model validity Randomized, controlled double-blind?

No details except exclusions TENS 80-100 Hz or ALTENS 2 4 Hz and Sham TENS with or without exercise Variable electrode placement n = 31 TENS/ALTENS 42 treatments of 45 min n = 34 TENS/ALTENS + exercise n = 31 sham TENS/ALTENS n = 29 sham TENS/ALTENS + exercise All groups also had hot packs for mean 23 days Ankylnsing spondylitis; ALTENS vs sham placebo no previous surgery ALTENS at 5 Hz electrodes to acupuncture points 10 treatments of 20 min n = 10 ALTENS; n = 10 placebo

Valid pain and activity measurement All groups improved but no clinical/statistical difference between them Follow-up 2 mouths, scores back to baseline High withdrawal rate accounted for appropriately 33% reported side-effects as minor skin irritation

0.84 Adequate model validity Many variables Uneven postsurgery matching Patients blind Randomized

Valid pain and activity measurement Initial outcome: ALTENS 90% improved; placebo 40% No follow-up No side-effects or withdrawals recorded

0.55 Adequate model validity Randomized controlledPartial blinding to patient and practitioners

No details except exclusions TENS at 100 Hz vs placebo 20 standardized treatments for 30 rain over 10 weeks n = 14 TENS; n = 12 placebo; n = 14 no treatment control

Valid measures for pain and motivation Improvement for pain TENS 43%, placebo 18% at 10 weeks No significant difference long-term Follow-up No withdrawals recorded No side-effects recorded

0.57 Adequate model validity Pseudo-randomized, controlled doubleblind?

Melzack et al (1983)~" Low back pain; no details

Deyo et al (1990)~7

Gemignani et al (1991) 38

Marchand et al (1993) 39

ALTENS at 4-8 Hz vs gentle mechanical massage Electrode usually over site of pain Up to x 10, 30-min treatments over 2 weeks Average 5.1 treatments n = 20 ALTENS; n = 21 massage No placebo

6. Marchand et al (1993)39: randomized, controlled trial of TENS (n = 12) vs placebo (n = 12), described as double-blind. Subjects, inclusion/exclusion criteria, treatment and implementation, blinding of subjects well described. Shortcomings: 'Pseudo-random' trial 'controlling for ... sex, weight, diagnosis and pain severity.'; appearance of treatment and placebo equipment different; partial blinding of

0.55 Low model validity: too many variables Difficult to extract relevant data

randomization process and practitioners; no a priori estimation of numbers; partial evaluation of randomization, blinding and outcome measures. No details of withdrawals. Quality index 0.57. The total number of subjects in these six studies was 288 with an average age range of 45-50 years and an approximately equal number of men and women. Most

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Complementary Therapies in Medicine Table 2 Summaryof data extractedfrom the controlledtrials

Controlled trials contributingdata to the meta-analysis Number of trials Total number of subjects Number improved Number identifiedwith previous surgery(2 studies) Number receivingALTENS Number receivingALTENSimproved Number receivingTENS Number receivingTENS improved Number receivingplacebo Number receivingplaceboimproved

Number 6 288 131 118 30 26 118 54 140 51

Percentage 95% CI 46 35 10 87 41 46 49 36

80-93 37-55 28~44

Odds ratio of all controlledtrials ALTENS/TENSvs placeboOR = 2.1 95% CI 1.3-3.4. Odds ratio of ALTENStrials alone OR = 7.2 95% CI 2.6-20.0. Odds ratio TENS trials alone OR = 1.5 95% CI 0.9-2.6. Table 3 Summaryof data extractedfrom the uncontrolledtrials Data summaryfor uncontrolledtrials Number Number of trials 40 Total number of subjects 2830 Number improved 1744 Number identifiedwith previoussurgery(14 studies) 300 Number receivingALTENS 176 Number receivingALTENSimproved 120 Number receivingTENS 2654 Number receivingTENS improved 1624

Percentage 95% CI 62 46 6 68 94 62

61-75

5%65 Uncontrolled pooled data in an experimental weighted meta-analysis vs the average placebo effect in controlled trials OR = 4.1 95% CI 3.74.5. had a history of several years of low back pain not responding to previous treatment. They formed a multipathology group, many of whom had had unsuccessful surgery. The studies were carried out in Canada, Italy and USA. The overall methodologies described in these papers were comparable in terms of this review. Percentages of subjects receiving TENS, ALTENS and placebo treatments and those responding positively were calculated including confidence intervals (Table 2). One hundred and eighteen subjects in four trials received TENS and 54 subjects (45.8% with 95% CI 37%, 55%) showed a positive response to treatment. Thirty subjects in two trials received ALTENS, with 26 (86.7% with 95% CI 80%, 93%) showing a positive response by the end of the study period. One hundred and forty subjects received placebo treatment in the six trials, with 51 (36.4% with 95% CI 20%, 44%) showing significant levels of pain relief. The difference in pain between subjects receiving ALTENS or TENS compared with placebo treatment was significant (P = 0.005). More patients receiving ALTENS showed improved ranges of movement compared with placebo (P = 0.001). A summary of data from the 40 uncontrolled trials not meeting the inclusion criteria is contained in Table 3. Meta-analysis shows an increase in the odds of improvement in pain and activity as follows: 1. TENS reduces pain with an OR of 1.6 (95% CI 0.9, 2.7) compared with placebo 2. ALTENS reduces pain with an OR of 7.2 (95% CI 2.6, 20.0) compared with placebo 3. TENS/ALTENS reduces pain with an OR of 2.1 (95% CI 1.3, 3.4) compared with placebo

4. From the two ALTENS trials qualifying for inclusion in this review, ALTENS with an OR of 6.6 (95% CI 2.4, 18.6) is more likely than placebo to improve activity. Melzack et aP 6 assessed straight leg raise and back flexion; Gemingnani et a138used Schober's test and finger to floor distance in anterior and lateral flexion 5. TENS and mixed TENS/ALTENS carry some risk of side-effects, usually described as mild skin irritation, worsening pain or mild mental disturbances, with an OR of 1.1 (95% CI 0.6, 2.1) among those studies reporting side-effects 6. There are insufficient data to evaluate the following comparisons: the effect of ALTENS/TENS on activity and return to work; the effect of ALTENS on return to work; and the effect of TENS on activity (Deyo et aP vinclude various measures of activity but there is no clinical or statistical difference between active TENS treatment and sham treatment groups). Follow-up data are shown in Table 4. Deyo et a136 was the only study to present and analyse data on patients who withdrew. The number of trials in the review and meta-analysis was too small to test the impact of publication bias. Because of the lack of suitable data, it was not possible to conduct a meta-analysis on long-term effects of treatment.

DISCUSSION This review and analysis is severely restricted by the lack of quality, randomized controlled trials, with only

A review of the treatment of chronic low back pain with acupuncture Table 4

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Follow-up data from the six included studies

Study

Follow-up period

Outcome on follow-up

Thorsteinsson et al (1977)34 Jeans (1979) 35 Melzack et al (1983) 36 Deyo et al (1990)37 Gemignani et al (1991) 38 Marchand et al (1993) 3~

3 and 6 months Unspecified No follow-up 2 months No follow-up 3 and 6 months

Continuing pain relief Gradual and continuing decrease in pain

six of the identified 68 papers fulfilling the inclusion criteria as placebo-controlled trials. The six studies presented a mixture of chronic low back pathologies, used different trial methodologies and application of active treatments and varied in quality and strength. Despite these limitations, the review represents the best available evidence to date on the usefulness of ALTENS/TENS in treating chronic low back pain. Treatment appears to be a suitable, inexpensive technique which is more effective than a placebo for relieving pain and increasing range of movement and should be considered for inclusion as part of a treatment programme for patients with failed lumbar surgery. The only recorded adverse sideeffects are some minor skin irritation at the site of electrode placement and occasional, temporary worsening of pain. Self-administered treatment at home with a suitable unit would also be worth considering as a potentially useful and cost-effective strategy. However, this review highlights the necessity of confirming the efficacy of TENS and/or ALTENS in the management of chronic low back problems with a powerful definitive study. Whilst providing some evidence to support the use of TENS and/or ALTENS, these conclusions contrast with those drawn by recent Dutch ~*and Canadian 1~studies. The negative conclusion of the Canadian study was based on only five random controlled trials (two of which did not meet the inclusion criteria for this review), two uncontrolled trials and three descriptive/expert opinion studies. The Dutch review examined only three trials, one of which did not fulfil the criteria for inclusion in this review. However, in this current study, over 600 studies were examined to produce the first list of 68, which was subjected to review to be reduced to six for analysis, and this represents a more thorough examination of the published evidence and provides some support for the current clinical use of these treatments. It does seem incredible to the authors that even after more than 25 years of extensive, global use, there is not more substantial evidence to support the efficacy of ALTENS/TENS in the management of low back pain. It could be revealing to conduct a similar review of the effectiveness of these therapies in the treatment of other musculoskeletal problems to determine whether or not the evidence is more compelling in these areas, especially with the increasing emphasis on evidence-based treatments. However, the

Scores back to baseline TENS and placebo still had positive effect on pain ratings but no significant differences between the two, unlike the period immediately after conclusion of treatment

authors suspect that the evidence may be of a similar quality to that reported in this review. A definitive study must take the form of a well designed, double-blind, randomized, placebo-controlled trial, taking place in different study centres and should take into account the following considerations: 1. A three- or four-armed study comparing (a) TENS, (b) ALTENS with (c) credible placebo and/or no treatment control 2. A study with at least 80% power for detecting differences in the chosen measurement scales, using statistical methods of power calculations to determine the required number of patients to meet the trial outcomes based on the results of the meta-analysis of the studies in this review, as a multicentred study with adequate blinding of practitioners, assessors and patients 3. Adequate allocation concealment and qualitybased trial structure after Chalmers et aP3 4. Standardized intervention with adequate baseline matching of subjects using a suitable, specific, differential diagnosis for low back pain, e.g. Sweetman et al4 5. Set parameters for TENS/ALTENS, electrode placement, length of treatments, outcome measurements for pain, activity, functional status, return to work and follow-up at 6 months 6. Elimination as far as possible of all other treatment variables with the debatable exception of a set of simple flexion and extension lumbar exercises for all subjects, in keeping with current practice of remedial exercises. The definitive study on the most appropriate use of TENS/ALTENS for the treatment and management of chronic low back pain has yet to be produced.

ACKNOWLEDGEMENTS With thanks for support and guidance to Dr E Dewhurst, Mr R Jarvis and Prof. M. Saks of The De Montfort University, Leicester, UK, Prof. A. Bennett; lain Chalmers and team at the U K Cochrane Centre, Oxford, UK, Beverly Shea of the Cochrane Musculoskeletal Group, Ottawa, Canada, Dr C. Bombardier, Prof. A. Nachemson and Rosmin Esmail of the Cochrane Collaboration Back Subgroup, Toronto, Canada. M.W.E acknowledges financial help from Body Clock Healthcare Ltd, London, UK, and the Society of Electrotherapists, Leicester, UK.

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ComplementaryTherapies in Medicine

REFERENCES

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APPENDIX: STUDIES NOT MEETING THE INCLUSION CRITERIA AND EXCLUDED FROM THIS REVIEW

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A review of the treatment of chronic low back pain with acupuncture

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