Systematic reviews of complementary therapies - an annotated bibliography. Part 1: Acupuncture

  • Klaus Linde1, 2Email author,

    Affiliated with

    • Andrew Vickers3,

      Affiliated with

      • Maria Hondras4,

        Affiliated with

        • Gerben ter Riet5, 6,

          Affiliated with

          • Johannes Thormählen1,

            Affiliated with

            • Brian Berman7 and

              Affiliated with

              • Dieter Melchart1

                Affiliated with

                BMC Complementary and Alternative Medicine20011:3

                DOI: 10.1186/1472-6882-1-3

                Received: 22 March 2001

                Accepted: 16 July 2001

                Published: 16 July 2001

                Abstract

                Background

                Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with acupuncture. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of acupuncture; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pretested form and summarized descriptively.

                Results

                From a total of 48 potentially relevant reviews preselected in a screeening process 39 met the inclusion criteria. 22 were on various pain syndromes or rheumatic diseases. Other topics addressed by more than one review were addiction, nausea, asthma and tinnitus. Almost unanimously the reviews state that acupuncture trials include too few patients. Often included trials are heterogeneous regarding patients, interventions and outcome measures, are considered to have insufficient quality and contradictory results. Convincing evidence is available only for postoperative nausea, for which acupuncture appears to be of benefit, and smoking cessation, where acupuncture is no more effective than sham acupuncture.

                Conclusions

                A large number of systematic reviews on acupuncture exists. What is most obvious from these reviews is the need for (the funding of) well-designed, larger clinical trials.

                Background

                Complementary therapies are widely used throughout the world [1,2,3] but their effectiveness is controversial. Although these therapies are clearly under-researched compared to their relevance in actual care, the total number of clinical trials in many areas is considerable [4]. There is a need to know what evidence is available and which questions have not yet been addressed. Systematic reviews are considered to be the best available method to this end [5]. In recent years an increasing number of such reviews has been performed in a variety of complementary therapies. The objective of our series of reports is to provide a comprehensive collection and transparent summary of the available systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, and homeopathy). It was not our primary objective to assess efficacy as we do not consider a review of reviews of a large number of interventions an appropriate tool for this purpose. However, when summarizing the results of systematic reviews it is unavoidable to cite their conclusions on efficacy. Our results are presented in three consecutive articles. This first article deals with acupuncture.

                Acupuncture is a therapy that involves the stimulation of defined points on the skin typically by inserting needles; however, related techniques such as manual (acupressure), electrical or laser stimulation of acupuncture points are also often summarised under this term [6,7]. Acupuncture is, together with the use of herbal medicines and other treatment modalities, a part of traditional Chinese medicine. In the West it is often used as a single therapy. The basic idea underlying acupuncture is that disorders related to the flow of Chi (the traditional Chinese concept translated as vital force or energy) can be prevented or treated by stimulating the relevant points on the body surface.

                Methods

                To be included in this overview reviews had to meet the following criteria: 1) Report reviews prospective (not necessarily controlled) clinical trials of acupuncture or related methods (such as acupressure) in humans. 2) Reports explicitly describe, at least, one of the following issues: a) methods for searching primary studies and eligibility criteria for primary studies; b) methods to assess quality aspects; c) methods to summarise the results of the primary studies. 3) Reports are published in journals, books, theses, or the internet. Reviews published before 1989 and as abstracts only were not included. 4) The primary focus of the report is on treatment effects (not diagnosis, side effects, risks, etc.). There were no language restrictions. Disease-oriented reviews including a variety of interventions were included only if they reviewed at least 4 acupuncture trials.

                The primary source for identification of systematic reviews was the register of the Cochrane Complementary Medicine Field. For the compilation of this register a variety of databases including Medline, Embase, CISCOM, AMED and other sources have been searched. In addition, we searched 1) Medline 1989 to July 2000 using a standard strategy to identify systematic reviews [8] (see strategy list) combined with the terms acupuncture or acupressure; and 2) the Cochrane Library (last check in issue 2000, 3). Bibliographies of articles obtained and relevant textbooks were screened for further potentially relevant articles. The literature list from the Complementary Medicine Field register was screened in a first step independently by two reviewers who excluded all references for which they were sure that the papers were not systematic reviews. Abstracts of the publications identified by other means were screened by one reviewer. Full copies were obtained for all potentially relevant papers. One (in 46% of papers), two (53%) or three (1%) reviewers checked eligibility and extracted information (bibliographic details, topic, intervention, inclusion criteria, methodological issues, studies and number of patients included, results, and conclusions) from included reviews using pretested forms. For this report the included reviews were summarised in a tabular format giving basic information on the conditions, interventions, comparisons, number of studies reviewed, methodological features, results, and conclusions drawn by the reviewers (if possible in the original wording). We assessed the following methodological features: Comprehensiveness of the literature search (scored if in addition to Medline other databases and non-electronic sources were searched), whether inclusion and exclusion criteria were explicitly listed, whether the quality of primary studies was assessed using fomal methods (such as scores or checklists), whether a summary of results was provided for each included study, and whether a quantitative meta-analysis was performed.

                If several review publications by the same team of reviewers with the same focus and published within a time span of 3 years were available these were considered as updates unless inclusion criteria for the two versions were clearly different.

                Strategy to search systematic reviews in the Medline database(Ovid Version)[8]

                #1 systematic adj reviews.tw.

                #2 data adj synthesis.tw.

                #3 published adj studies.ab.

                #4 data adj extraction.ab.

                #5 meta-analysis/

                #6 meta analysis.ti.

                #7 comment.pt

                #8 letter.pt.

                #9 editorial.pt.

                #10 animal/

                #11 human

                #12 10 not (10 and 11)

                #13 search terms for specific therapy

                #14 13 not (7 or 8 or 9 or 12)

                #15 or/1-6

                #16 14 and 15

                Results

                From a total of 48 potentially relevant reviews preselected through the screening process, 39 (published in 45 papers) met the inclusion criteria [953]. Five reviews were excluded as they were not truly systematic reviews (not meeting inclusion criterion 2) [5458] and 4 as they did not focus on treatment effects but on methodological issues [5962].

                As expected, many reviews addressed pain (see table 1). Three reviews (published 1989 [10,12], 1990 [11] and 2000 [9]) focused on chronic pain. The study samples (total number of trials covered in any of the reviews 72) and review methods differed considerably among the reviews but all agreed that the available evidence is inconclusive. Back and neck pain were addressed in six reviews (total number of trials covered for each back and neck pain 11). Conclusions regarding back pain were contradictory [13, 1519] while the evidence regarding neck pain was considered inconclusive [13,14]. Six reviews addressed various types of headaches (total number of trials covered 25). The largest review which focused on migraine and tension-type headache [21] drew tentatively positive conclusions. The remaining reviews included fewer studies and the evidence was considered inconclusive [20,[2225]].
                Table 1

                Systematic reviews of clinical trials of acupuncture & acupressure in pain

                Author Year

                Indication

                Controls

                Studies

                features 1 / 2 / 3/ 4 / 5

                Results

                Conclusion

                Chronic

                      

                pain

                      

                Ezzo 2000

                chronic

                sham,

                51 RCT

                y / y / y /

                Positive results in 21 studies, negative in 3,

                Limited evidence that acupuncture is

                [9]

                pain

                placebo, no

                 

                y / n

                and neutral in 27. Better studies more often

                more effective than no treatment,

                  

                treatment,

                  

                negative or neutral

                inconclusive evidence regarding

                  

                standard

                   

                placebo, sham and standard care

                ter Riet

                chronic

                sham,

                51 CCT

                y / y / y /

                Trials small and of low quality. 24 with

                The efficacy of acupuncture in the

                90/89

                pain

                other, no

                 

                y / n

                positive and 27 with negative results. Better

                treatment of chronic pain remains

                [10,11]

                 

                treatment

                  

                studies more often negative

                doubtful

                Patel 89 [12]

                chronic

                sham, no

                14 RCT

                n / y / n

                Overall patients receiving acupuncture were

                Available evidence positive but

                 

                pain

                treatment,

                 

                / y / y

                18% (p < 0.01) more likely to experience

                definitive conclusions difficult due to

                  

                standard

                  

                improvement

                various potential sources of bias

                Smith 2000

                back &

                sham,

                13 RCT

                y / y / y /

                5 studies positive, 8 studies negative; better

                No convincing evidence for the

                [13]

                neck pain

                other, no

                 

                y / n

                studies reported more often negative results

                analgetic efficacy of acupuncture for

                  

                treatment

                   

                back and neck pain

                White 99

                neck pain

                sham,

                14 RCT

                y / y / y /

                7 studies positive, 7 negative. Of the 8 better

                No convincing evidence for the

                [14]

                 

                other, no

                 

                y / n

                studies 5 negative, 3 positive

                effectiveness of acupuncture for neck

                  

                treatment

                   

                pain

                van Tulder

                low back

                sham,

                11 RCT

                y / y / y /

                Conclusions of primary authors positive in 8

                Authors would not recommend acu-

                99 [15,16]

                pain

                other, no

                 

                y / n

                studies, by reviewers for 2 studies.

                puncture as regular treatment for low

                  

                treatment

                  

                Methodological quality judged as low

                back pain. High quality trials needed

                Ernst 98 [17]

                back pain

                sham,

                12 RCT

                y / y / y /

                OR for improvement compared with all

                Acupuncture superior to various

                  

                other, no

                 

                y / y

                control interventions 2.30 (95%CI 1.28–4.13),

                control interventions although

                  

                treatment

                  

                with sham 1.37 (0.84–2.25). Majority of

                insufficient evidence whether

                     

                studies good quality

                superior to sham

                Longworth

                sciatica

                unclear

                1 RCT, 6

                p / p / n

                Most studies of poor quality; a large number

                There may be a role for acupuncture

                97 [18]

                  

                CCT, 31

                / y / n

                of patients seem to have benefited

                treatment of lumbar disk protrusions

                   

                uncontrolled

                  

                and sciatica

                   

                studies

                   

                ter Riet 89

                neck and

                unclear

                16 RCT, 6

                y / p / y

                Study design was generally poor. Results

                Due to the low methodological quality

                [19]

                back pain

                 

                CCT

                / n / n

                only discussed for a few better quality

                no definitive conclusions can be

                     

                studies

                drawn

                Headache

                      

                McCrory

                tension-

                sham,

                6 RCT

                y / y / y /

                3 of 4 sham-controlled trials positive (best

                Insufficient evidence to draw

                2000* [20]

                type

                physio-

                 

                y / n

                negative), physiotherapy better in 1 of 2 trials

                conclusions on the efficacy. Further

                 

                headache

                therapy

                   

                rigorous trials needed

                Melchart 99

                idiopathic

                sham,

                22 RCT

                y / y / y /

                Majority of 14 sham controlled trials with at

                Existing evidence suggests that

                [21]

                headaches

                other, no

                 

                y / y

                least a trend in favour of acupuncture. Trials

                acupuncture has a role in headache

                  

                treatment

                  

                vs. other treatments contradictory

                treatment. However, quality and

                      

                amount of evidence not fully

                      

                convincing

                Goslin 99

                migraine

                sham,

                6 RCT

                y / y / y /

                2 of 3 placebo-controlled trials positive,

                Insufficient data on acupuncture to

                [22]

                 

                other, no

                 

                y / n

                similar effects as drug treatment in 2 trials

                draw conclusions on its efficacy

                  

                treatment

                    

                Vernon 99**

                tension-

                sham,

                8 RCT

                y / y / y /

                2 of 4 sham-controlled trials positive, results

                Too few trials and contradictory

                [23]

                type and

                other, no

                 

                y / n

                vs. physiotherapy contradictory

                findings precluding definitive

                 

                cervicogeni

                treatment

                   

                conclusions

                 

                c

                     

                ter Riet 89

                tension

                sham, other

                7 RCT, 1

                y / p / y

                Small study size and methodological

                No definitive conclusions on the

                [24]

                type

                treatment

                CCT

                / n / n

                problems make the available trials

                effectiveness of acupuncture for

                 

                headache

                   

                uninterpretable

                headache can be drawn

                ter Riet 89

                facial pain

                sham

                2 RCT

                y / p / y

                Methodological quality poor

                No definitive conclusions possible

                [25]

                   

                / y / n

                  

                Pain

                      

                various

                      

                Ernst 98 [26]

                acute

                sham,

                11 RCT, 5

                y / p / y

                The majority of trials imply that acupuncture

                Acupuncture can alleviate dental pain

                 

                dental pain

                other, no

                CCT

                / y / n

                is effective in dental analgesia

                but additional research necessary

                  

                treatment

                    

                Ernst 99 [27]

                temporoma

                other and

                3 RCT

                y / y / n

                3 comparisons with standard treatments and

                Available data suggest beneficial

                 

                n-dibular

                no

                 

                / y / n

                2 with no treatment with favorable effects of

                effects; more rigorous, sham-

                 

                joint

                treatment

                  

                acupuncture

                controlled trials needed

                 

                dysfunction

                     

                *Disease focused review on a variety of interventions including acupunture and acupressure; **Disease focused review on a variety of complementary medicine interventions including acupunture and acupressure Features: 1 = comprehensive search, 2 = explicit inclusion criteria, 3 = formal quality assessment, 4 = summary of results for each included study, 5 = meta-analysis; y = yes, p = partly, n = no, - = not applicable, ? = unclear RCT = randomized controlled trials, CCT = non-randomized controlled trials, CS = cohort studies; OR = odds ratio, RR = rate ratio

                The available trials suggest that acupuncture is effective in postoperative pain after dental treatment and temporomandibular dysfunction although further research is still considered necessary [26,27,53].

                Systematic reviews of acupuncture and acupressure for rheumatic diseases, addiction, nausea and asthma are summarized in table 2. A variety of rheumatic conditions has been addressed in five reviews. The limited evidence available so far suggests that acupuncture may have favorable effects in fibromyalgia [28]. The majority of the available trials on osteoarthritis report improvement with both sham and true acupuncture but no significant differences between the two [29]. For a variety of other rheumatoid diseases the evidence was considered inconclusive [30,31,32].
                Table 2

                Systematic reviews of clinical trials of acupuncture & acupressure in rheumatic diseases, addiction, nausea and asthma

                Author Year

                Indication

                Controls

                Studies

                Features 1 / 2 / 3 / 4 / 5

                Results

                Conclusion

                Rheumatic diseases

                      

                Berman 99

                fibromylgia

                sham, other

                3 RCT, 3 CS

                y / y / y /

                Acupuncture more effective than sham for

                Limited amount of evidence positive.

                [28]

                 

                treatments

                 

                y / n

                symptoms and global ratings

                Further research needed

                Ernst 97 [29]

                osteoarthriti

                sham, other

                13 RCT

                y / p / n

                Both sham and true acupuncture improve

                The notion that acupuncture is

                 

                s

                and no

                 

                / y / n

                symptoms but better trials suggest no

                superior to sham-needling is not

                  

                treatment

                  

                difference between the two

                supported by data from controlled

                      

                clinical trials

                Lauten-

                inflammator

                sham, no

                2 RCT, 7

                n / p / n

                Controlled trials contradictory, quality often

                Acupuncture cannot be

                schläger 97

                y

                treatment,

                CCT, 9 CS

                / y / n

                low

                recommended for rheumatoid

                [30]

                rheumatoid

                other acup.

                   

                arthritis, spondarthropathy, lupus

                 

                diseases

                    

                eryth., sclerodermia

                Jacobs 91**

                rheumatic

                sham, other

                23 CCT

                p / y / n

                7 trials positive, 13 trials no effect over

                No specific conclusion on

                [31]

                diseases

                treatment

                 

                / y / n

                placebo or control, 3 trials unclear

                acupuncture (generally: no

                      

                convincing evidence for alternative

                      

                therapies in rheumat.)

                ter Riet 89

                rheumatoid

                sham

                1 RCT,

                y / p / y

                Only 1 trial summarized; this found positive

                No definitive conclusions possible

                [32]

                arthritis

                 

                2CCT

                / n / n

                effects on pain but not on inflammation

                 

                Addiction

                      

                White

                smoking

                sham, other

                20 RCT

                y / y / y /

                Acupuncture vs. sham: OR for cessation

                There is no evidence for the specific

                2000/99

                cessation

                and no

                 

                y / y

                1.22 (95%CI 0.99–1.49) after treatment and

                effectiveness of acupuncture in

                [33,34]

                 

                treatment

                  

                1.02 (0.72–1.43) at 12 months. No difference

                smoking cessation greater than a

                     

                compared to other interventions, better than

                placebo effect

                     

                no treatment

                 

                White 97

                smoking

                sham

                7 RCT

                y / y / y /

                6 of the 7 studies do not yield cessation rates

                Acupuncture for smoking cessation

                [35]

                cessation

                  

                y / n

                that are significantly different from sham

                does not produce an effect greater

                     

                acupuncture

                than placebo

                Law 95* [36]

                smoking

                sham, other

                8 RCT

                p / p / n

                Compared to control 3% (95%CI -1 to 6%)

                Acupuncture is ineffective

                 

                cessation

                and no

                 

                / n / y

                more participants stopped smoking with

                 
                  

                treatment

                  

                acupuncture

                 

                ter Riet

                A. smoking

                sham, other

                A. 13 RCT, 2

                y / p / y

                A. 3 of 15 studies positive

                Claims that acupuncture is effective

                90/89 [37,38

                cessat.

                and no

                CCT

                / y / n

                 

                for the treatment of tobacco, alcohol

                39]

                B. alcohol

                treatment,

                B. 1RCT, 1

                 

                B. 2 of 2 studies positive

                and heroine addiction are not

                 

                addict.

                other acu

                CCT

                  

                supported by sound clinical research

                 

                C. heroine

                 

                C. 5 CCT

                 

                C. 3 of 5 studies positive

                 
                 

                addict.

                     

                Nausea

                      

                Lee 99 [40]

                postoperati

                sham, other

                19 RCT

                y / p / y

                RR of early vomiting compared to

                Acupuncture equivalent to commonly

                 

                ve nausea

                and no

                 

                / y / y

                antiemetics 0.89 (95%CI 0.47–1.67) and to

                used antiemetic drugs. More effective

                 

                (prevention)

                treatment

                  

                placebo 0.47 (0.34–0.64), late vomiting 0.81

                than placebo in first 6 h after surgery

                     

                (0.46–1.42)

                in adults but no benefit observed in

                      

                children

                Aikins

                nausea in

                sham, no

                7 RCT

                y / p / n

                6 of 7 P6 acupressure trials positive, 1 trial

                Available evidence positive but

                Murphy 99**

                pregnancy

                treatment

                 

                / y / no

                on P6 electrical stimulation positive

                equivocal

                [41]

                      

                Jewell 98*

                nausea in

                sham, no

                4 RCT

                y / y / y /

                3 of 4 P6 acupressure trials positive, 2 cross-

                Available evidence positive but

                [42]

                early

                treatment

                 

                y / y

                over trials excluded, best trial negative

                equivocal

                 

                pregnancy

                     

                Vickers 96

                nausea in

                sham, other

                33 CCT

                y / y / y /

                27 of 33 trials positive, 11 of 12 sham-

                Except when administered under

                [43]

                surgery,

                and no

                 

                y / n

                controlled randomized trials positive

                anesthesia P6 acupuncture point

                (stimulation

                pregnancy,

                treatment

                   

                stimulation seems to be an effective

                at point P6)

                chemother.

                    

                antiemetic technic

                Asthma

                      

                Linde 98 [44]

                asthma

                sham

                7 RCT

                y / y / y /

                Highly heterogeneous trials; two positive, five

                It is not yet possible to make any

                 

                (acute

                  

                y / p

                found no difference

                recommendations about the practice

                 

                attack trials

                    

                of acupuncture in the treatment of

                 

                excl.)

                    

                asthma

                Linde 96 [45]

                asthma

                sham, no,

                15 RCT

                y / y / y /

                Contradictory results, highly heterogeneous

                There is insufficient data to draw

                  

                other

                 

                y / n

                trials

                reliable conclusions about the

                  

                treatment

                   

                effectiveness of acupuncture for

                      

                asthma

                Kleijnen 91

                asthma

                unclear

                9 RCT, 4

                y / p / y

                Quality low, contradictory results

                Claims that acupuncture is effective

                [46] & ter

                  

                CCT

                / n / n

                 

                in the treatment of asthma are not

                Riet 89 [47]

                     

                based on well performed clinical trials

                legend see table 1

                The trials on smoking cessation show in a fairly consistent manner that acupuncture does not seem to have lasting effects over sham acupuncture [3339] (total number of trials covered 22). The only identified review on alcohol and heroin addiction which met our inclusion criteria was published in 1989 [39]; several narrative reviews including new trials on the topic are available (for example [55]).

                Trials on nausea are unique in acupuncture research as they focus almost completely on acupuncture or acupressure at a single point (P6). There is good evidence that both acupuncture and acupressure are effective in postoperative nausea (total number of trials covered 24) while the results are equivocal for early morning sickness [4043] (total number of trials covered 8). Most of the trials report positive results but a recent high quality trial could not replicate the findings [63]. Several studies suggest that stimulation of P6 is also effective in treating chemotherapy-induced nausea [43].

                Results on asthma are contradictory and all available trials are very small [4447] (total number of trials covered 15).

                Systematic reviews of acupuncture and acupressure for a variety of additional conditions are summarized in table 3. While the findings of the available trials on tinnitus and weight reduction do not suggest important effects [48,49,50] a review on acupuncture as an adjunct treatment in stroke rehabilitation found promising results [51].
                Table 3

                Systematic reviews of clinical trials of acupuncture & acupressure in various conditions

                Author Year

                Indication

                Controls

                Studies

                Features 1 / 2 / 3 / 4 / 5

                Results

                Conclusion

                Park 2000

                tinnitus

                sham, other

                6 RCT

                y / y / y /

                2 unblinded studies positive whereas 4

                No evidence from rigorous RCT that

                [48]

                 

                treatment

                 

                y / n

                blinded studies showed no significant effects

                acupuncture has specific effects in

                     

                of acupunct.

                the treatment of tinnitus

                Dobie 99 *

                tinnitus

                sham, other

                6 RCT

                p / p / p

                No significant effects shown. Patients in

                No specific conclusions for

                [49]

                 

                treatment

                 

                / p / n

                cross-over studies tend to prefer

                acupuncture drawn (generally: no

                     

                acupuncture

                treatment well established)

                Ernst 97 [50]

                weight or

                sham

                4 RCT

                ? / y / y

                Two studies positive effect mainly on

                Claims that acupuncture reduces

                 

                appetite

                  

                / y / y

                appetite, two studies (better quality) negative

                weight or appetite not based on well-

                 

                reduction

                    

                performed clinical trials

                Ernst 96 [51]

                stroke

                no

                5 RCT, 1

                y / y / n

                All trials suggest positive effects on

                Evidence encouraging but not

                 

                rehabilitatio

                treatment

                CCT

                / y / n

                functional recovery; numerous

                compelling

                 

                n

                (routine

                  

                methodological problems

                 
                  

                only)

                    

                Harris 97

                various

                sham,

                23 clinical

                p / n / y

                P6 acupressure effective for nausea, other

                No clear conclusion beyond results

                (only acu-

                 

                other, no

                studies

                / n / n

                research scarce and low quality

                drawn

                pressure)

                 

                treatment

                    

                [52]

                      

                Rosted 98

                dentistry

                sham,

                15 RCT

                y / p / y

                Most studies with relevant methodological

                The value of acupuncture as an

                [53]

                (mainly

                other, no

                 

                / n / n

                problems. 11 of 15 trials with positive results

                analgesic must be questioned due to

                 

                temporoma

                treatment

                   

                problems in the trials. But the effect

                 

                ndibular

                    

                in temporomandibular dysfunction

                 

                dysfunction

                    

                and facial pain seems real

                 

                )

                     

                legend see table 1

                Finally, there is one review summarizing research on acupressure for various conditions (acceptable evidence only available for nausea [52]) and another on acupuncture in various conditions related to dentistry (reporting promising evidence for temporomandibular dysfunction [53]).

                Discussion

                Although a considerable number of clinical trials on acupuncture is available the evidence so far is very often inconclusive. Apart from postoperative nausea (positive) and smoking cessation (negative) the reviewers apparently felt unable to make clear conclusions whether acupuncture was effective or not. This finding is somewhat frustrating. The primary problem in acupuncture studies seems to be sample size (most studies are very small). For example, median sample sizes of trials in low back pain, headache and osteoarthirits were 50 [16], 37 [21] and 31 [29], respectively. A second relevant problem is methodological quality. There was an almost uniform call for large, well-designed studies. Why are so few such studies available?

                One reason is probably the lack of funding for such studies. There is little industrial interest in acupuncture, so major funding has to come mainly from public resources. In several countries a limited number of larger studies (on low back pain [64] with planned 170 patients and on headache [65] with 300 patients in the UK funded by the NHS; and on osteoarthritis [personal communication, Brian Berman] with 570 patients in the US funded by the NIH) is now underway which might bring some advances. A second - partly related - reason is that a competent research infrastructure has been developed only very slowly. A third reason is that clinical research in acupuncture is difficult. Acupuncture (as other non-drug therapies like physiotherapy) is a term for describing a group of quite heterogeneous interventions. Some providers clearly find it misleading to include techniques without needling into systematic reviews of acupuncture while those who apply acupressure or laser acupuncture often hold the opinion that the crucial issue is the stimulation of the correct point no matter by which way. Acupuncture strategies for the treatment of a specific condition can be highly variable. Some acupuncturists use similar approaches in all patients with a given Western diagnosis while others consider this as inadequate and claim that the treatment has to be "individualized." This is often misunderstood: Patients with the same Western diagnosis get different treatment because they have different diagnoses according to traditional Chinese medicine which uses different disease groups. Furthermore, different schools of acupuncture exist within Western and more traditional approaches.

                Another significant problem in acupuncture research is choosing appropriate placebo controls if the objective is to evaluate specific effects. Techniques applied include mock transcutaneous nerve stimulation, sham laser acupuncture, needling superficially, needling wrong or inadequate points etc. There is some evidence that different types of acupuncture "placebos" have different effects [59]. For example, techniques that involve needling (and which are less likely to be distinguishable and therefore are considered as better for blinding) can cause relevant physiological responses [66].

                Several reviews described a negative correlation between study quality and outcome (better studies were more often negative; for example [9,11,13]). This finding has to be interpreted with caution. Many reviews included trials with very different control groups: waiting list or no treatment, the various "placebo" techniques listed above, and a variety of active controls. If acupuncture has at least some placebo effect, attributable to the psychological effects of being administered a novel therapy, one would expect placebo-controlled trials to show smaller differences between groups than trials without placebo control. Acupuncture trials without placebo control cannot be blinded and therefore typically score lower on quality scales. Given that links between study quality and outcome are confounded by the issues of non-specific effects, and given that trials with different control groups answer different questions, analyses checking the influence of quality aspects on outcomes should only be performed within groups of trials with comparable controls.

                This annotated bibliography of systematic reviews should also be interpreted with great caution. The risk of oversimplification in a systematic review is great. In a review of reviews it is extreme. We summarise the conclusion of a systematic review in a single phrase. Clinical decisions for treatment of individual patients should not be based on our work. For this, patients and health care professionals have to turn to the original reviews. Our aim was to provide a clear summary of what is available and where further information can be found. We tried to be as comprehensive as possible in our search but cannot exclude that we have overlooked eligible work, particularly if this was not published in a journal.

                Our findings are generally in accordance with those of a panel of the National Institutes of Health reporting on acupuncture in 1998 [67]. However, the conclusions of the panel that the evidence on acupuncture is promising for a variety of conditions but not conclusive seems slightly more optimistic than the picture which emerges from the available systematic reviews.

                We did not systematically search the literature on systematic reviews of side effects of acupuncture. We came across one such review which had collected case reports [68]. However, for a reliable assessment of safety large scale prospective studies or effective surveillance systems are needed in addition.

                In conclusion, while in some areas only older reviews are available and some minor topics are not reviewed at all it is obvious that what is needed is new primary research and not new systematic reviews. Future trials should have larger sample sizes, rigorous methods, and should reflect principles and practice of acupuncture as applied in actual practice. Until conclusive data becomes available we must be aware that most decisions in health care regarding acupuncture are based - as in many other areas of medicine - on partial evidence about which reasonable people can disagree.

                Declarations

                Acknowledgements

                KL's work was partly funded by the NIAMS grant 5 U24-AR-43346 -02 and by the Carl and Veronica Carstens Foundation, Essen, Germany.

                Authors’ Affiliations

                (1)
                Centre for Complementary Medicine Research, Department of Internal Medicine II, Technische Universität, München
                (2)
                Institute for Social Medicine & Epidemiology Charité Hospital, Humboldt University
                (3)
                Memorial Sloan-Kettering Cancer Center
                (4)
                Consortial Center for Chiropractic Research, Davenport
                (5)
                NHS Centre for Reviews & Dissemination, University of York
                (6)
                Department of Epidemiology, Maastricht University
                (7)
                Division of Complementary Medicine, Department of Family Medicine, University of Maryland School of Medicine

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                69. Pre-publication history

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                © Linde et al 2001

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