The effectiveness of non-invasive treatments for active myofascial trigger point pain: A systematic review of the literature

International Journal of Osteopathic Medicine 9 (2006) 120e136 www.elsevier.com/locate/ijosm

Review

The effectiveness of non-invasive treatments for active myofascial trigger point pain: A systematic review of the literature Luke D. Rickards* 146 Marlborough Street, Henley Beach, Adelaide SA 5022, Australia Received 25 May 2006; received in revised form 20 July 2006; accepted 30 July 2006

Abstract Background: Myofascial pain syndrome associated with active myofascial trigger points is a common diagnosis in patients presenting with symptoms of neuromusculoskeletal pain. The literature details dozens of proposed treatment interventions used to treat myofascial trigger points. However, reliable evidence for the intra- and inter-effectiveness for many of these treatments appears deficient. Objectives: To review the evidence for the effectiveness of non-invasive interventions in the treatment of patients with myofascial pain resulting from active myofascial trigger points. Data sources: The following databases were searched from inception to May 2006: Medline, PubMed, CINAHL, EMBASE, PEDro, and CENTRAL/CCTR. The reference lists of retrieved studies were scanned to identify additional relevant trials. Study selection: Randomised controlled trials or quasi-randomised trials examining the effectiveness of non-invasive treatments for myofascial trigger point pain were included where the criteria for the diagnosis of trigger points were clearly stated and acceptable. Data extraction: The reviewer extracted trial information and scored trials for methodological quality. The data were standardised into a percentage score and the strength of the evidence of effectiveness was assessed using pre-specified criteria. Data synthesis: Twenty-three trials met the inclusion criteria for this review. Five types of treatments studied were as follows: laser therapies, electrotherapies, ultrasound, magnet therapies, and physical/manual therapies. Twenty of the twenty-three included trials assessed the treatment of MTrPs in the neck and/or upper trapezius region. According to the results of this review there is a significant evidence that laser therapy may be effective as a short-term intervention for reducing pain intensity in myofascial trigger point pain of the neck and upper back. Further research is necessary to determine the long-term effectiveness, the most effective type of laser, and the optimum dosage, duration and frequency of treatment. TENS appears to have an immediate effect in decreasing pain intensity in myofascial trigger point pain of the neck and upper back. However, there are insufficient data to provide the evidence of effectiveness for TENS beyond immediately after treatment. There is limited evidence for the use of FREMS, HVGS, EMS and IFC for myofascial trigger point pain. Moderate evidence derived from one high quality and two lower quality studies indicates that conventional ultrasound is no more effective than placebo or no treatment for myofascial trigger point pain in the neck and upper back. Preliminary evidence suggests that magnet therapy may be effective, however, further studies are needed to support the findings. Due to the heterogeneity of trials examining physical and manual therapies the current evidence did not exceed the moderate level. Trials examining manual techniques suggest that such approaches may be effective, however, no conclusions can be drawn regarding medium to long-term effectiveness or effect beyond placebo. Evidence for many of the commonly used treatments for myofascial trigger point pain is lacking.

* Tel.: þ61 8 8355 5534. E-mail address: [email protected] 1746-0689/$ - see front matter Ó 2006 Published by Elsevier Ltd. doi:10.1016/j.ijosm.2006.07.007

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Conclusions: Current evidence suggests that only a few of the numerous non-invasive physical treatments proposed for myofascial pain resulting from active myofascial trigger points may be effective, however, the clinical effectiveness of these interventions requires further research in higher quality trails. The heterogeneity of the included trials means that the conclusions of this review could be easily influenced by the results of a few additional high quality trials in the future. Future research should also address the effect of contributing and perpetuating factors. Ó 2006 Published by Elsevier Ltd. Keywords: Myofascial pain syndrome; Myofascial pain; Myofascial trigger point; Trigger point; Systematic review

1. Background Musculoskeletal pain is one among the leading reasons for visits to physicians and manual therapists, and around one-third of these patients meet the diagnostic criteria for myofascial pain syndrome (MPS).1e5 Simons et al.6 and Travell and Simons7 have defined myofascial pain syndrome as a condition caused by hyperirritable areas, called ‘myofascial trigger points’ (MTrP), within taut bands of skeletal muscle or fascia. Myofascial trigger points are painful on compression and may give rise to characteristic patterns of referred pain, tenderness, autonomic nervous system symptoms, and restricted range of motion.6,7 Travell and Simons7 describe the clinical features of MTrPs to include a taut muscle band containing a discrete nodule; a history of focal tenderness; a consistent and reproducible pattern of referred pain; a local twitch response caused by ‘snapping’ palpation; and a spontaneous exclamation of pain by the patient (‘jump sign’) as a result of mechanical pressure. Trigger points are classified as ‘active’ or ‘latent’ in nature, depending on the presence of a characteristic pattern of pain referral. Active MTrPs refer pain at rest, with muscular activity, and upon direct palpation. In comparison, latent MTrPs remain non-painful and only refer pain when steady direct pressure is applied.6,7 Trigger points can arise virtually in any muscle group. However, the most common sites are the muscles involved in maintaining posture: levator scapulae, upper trapezius, sternocleidomastoid, scalenes, and quadratus lumborum muscles.6,7 Patients who have active MTrPs usually report regional, persistent pain that often results in a decreased range of motion. Associated signs, such as joint swelling and neurologic deficits, are usually absent on physical examination, and the pain does not follow a dermatomal or nerve root distribution.6,7 The underlying aetiology of myofascial pain and MTrP pathogenesis appears to be multifactorial, with postural stresses, inefficient biomechanics, and repetitive overuse are the most frequently described causes.1,3,6 However, MTrPs present a complex of clinical findings that defy a simplistic explanation, and no substantiated

scientific theory exists that explains the precise physiological nature of these clinical entities.8,9e11 Although several theories have been suggested, the scarcity of data regarding MTrP pathophysiology has made the objective diagnosis and management of this disorder a clinical challenge.8,11e13 The proposed hypotheses for MPS and MTrP pathogenesis have included the energy crisis theory; the muscle spindle concept; and the motor endplate hypothesis.14 The 1999 edition of Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual proposes an ‘integrated hypothesis’, incorporating local myofascial tissues, the central nervous system, and biomechanical factors, that could account for the major clinical characteristics of MTrPs.6,8 The integrated hypothesis expands the previously proposed hypotheses to include presynaptic, synaptic, and postsynaptic mechanisms of abnormal depolarisation, involving excessive release of acetylcholine, defects of acetylcholinesterase, and up-regulation of nicotinic acetylcholine-receptor activity, respectively.8,15,16 The resultant muscle spasm may impair arterial inflow, and therefore the supply of oxygen, calcium and other nutrients necessary for muscle fibre relaxation. Continued spasm could cause damage to the involved tissues, which may precipitate the synthesis and release of endogenous algogenic and inflammatory substances that enhance nociception.11 The integrated hypothesis also combines available electrodiagnostic and histopathological evidences to provide the basis for a plausible pathogenesis of MTrPs, however, additional research and refinement are still necessary.8 In a recent histological study, the preliminary results of a novel microanalytical technique for assaying soft tissue using a microdialysis needle revealed significant differences in the levels of pH, substance P, CGRP, bradykinin, norepinephrine, TNF, and IL-1 in those subjects with an active MTrP, compared with subjects with a latent MTrP and normal subjects.17 Clinicians in many health care disciplines routinely identify and treat MTrPs. However, at present there are no official biochemical, electromyographic, or diagnostic-imaging criteria recognised for their definitive diagnosis.8,10,18 Therefore, the diagnosis of MTrPs is dependent on manual palpation skills and patient

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feedback.10,19 This has raised many concerns regarding the subjective nature in which MTrPs are diagnosed.10 Furthermore, there is currently no reliable list of physical diagnostic criteria for MTrPs.8,18 Research studies are yet to demonstrate that the physical features of MTrPs are reproducible among the different examiners, thereby establishing the reliability of the physical examination in the diagnosis of the MPS.10,18,20 Gerwin et al.20 showed that the interrater reliability of the different features varies, and that the interrater reliability of the identification of MTrP features among the different muscles also varies. One implication of this study is that researchers studying MPS or MTrPs need to define the MTrP for the purposes of their study. The criteria by which an MTrP is identified, or the diagnosis of MPS is made, need to be clearly stated in order to properly interpret the reliability of the study.20 Although MTrPs have been associated with poor inter- and intra-examiner reliability,8,10,18,20 Sciotti et al.10 and Gerwin et al.20 have demonstrated good to excellent clinical precision amongst a team of experienced clinicians in diagnosing the presence of MTrPs. However, a training period was found to be essential in order to achieve these results. The taut band and spot tenderness are considered the most reliable of the MTrP features and the minimal criteria for identification. Reproduced pain denotes an MTrP as active or latent. Referred pain patterns and the local twitch response are less reliable and are considered confirmatory signs.8,12,20,21 While various treatment methods are considered to be effective in the resolution of MTrP symptomatology, the mechanisms underlying the efficacy of MTrP treatments are also essentially unknown. This has given rise to a multitude of interventions used in the treatment of MTrP pain.10 In a preliminary search of the current literature, the following interventions were used in various studies examining or reviewing the treatment of active MTrPs: transcutaneous electrical nerve stimulation (TENS), electrical muscle stimulation (EMS),22 ischemic compression, myofascial release therapy, stretch with coolant spray, interferential current,23 stretch, ultrasound, direct dry needling,24 trigger point injection (with various solutions and medications),25 neuro-reflexotherapy,26 deep pressure soft tissue massage, hydro-collator superficial heat,12 exercise, yoga,13 acupuncture, ice massage,1 magnetic stimulation,2 laser therapy,27 botulinum toxin, topical anesthetic preparation,28 passive rhythmic release, active rhythmic release,8 counterstrain, highvelocity low amplitude thrust,16 biofeedback and clinical psychophysiology.29 Such a variety of therapies, each requiring different skills, levels of training and licensing, have the potential to leave many clinicians with a dilemma when deciding the best course of treatment for their patient.

Cummings and White4 conducted a systematic literature review examining the effectiveness of various needling therapies in the treatment of myofascial trigger point pain. The review compared ‘wet’ and ‘dry’ needling methods, and direct and indirect needling methods. The results suggest that needling appears to be an effective treatment for myofascial trigger point pain, as marked improvements were recorded in all groups that received this intervention. The effect was shown to be due to the needle itself, or due to placebo, rather than the injection of saline or drugs. The study concluded that further controlled trials are needed to investigate whether needling has an effect beyond placebo in treating myofascial trigger point pain. As there was no difference in effectiveness between wet and dry needling methods, the reviewers recommended dry needling techniques because they are safer and more comfortable for the patient. As the effectiveness of the most common invasive interventions for myofascial trigger point pain has been addressed by Cummings and White,4 this review examines only non-invasive interventions. It is hoped that such a study will be more useful for manual and physical therapists, who are generally not trained in invasive techniques. 2. Objectives The aim of this study is to review the evidence for the effectiveness of non-invasive interventions in the treatment of patients with myofascial pain resulting from active myofascial trigger points. 3. Study selection 3.1. Types of studies Randomised controlled studies or quasi-randomised studies examining the effectiveness of non-invasive treatment interventions for active myofascial trigger point pain were included. Studies examining the treatment outcomes of various interventions and those comparing different interventions were reviewed. The treatment group had to be compared with a placebo, no treatment, or other treatment interventions. Studies comparing invasive and non-invasive treatments were included if the active non-invasive treatment groups were compared with a placebo, or with a no treatment control group. Trials in which allocation to the treatment or control group was not concealed from the outcome assessor were excluded. 3.2. Types of participants Studies of males and/or females with the diagnosis of myofascial pain were included if the presence of active

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myofascial trigger points had been identified. A clear definition of the criteria for determining the diagnosis of active trigger point pain was required. The minimum criteria for diagnosis were the presence of a taut band and spot tenderness on palpation. 3.3. Types of intervention Studies were included where the intervention involved one or more types of non-invasive method aimed at the treatment of active myofascial trigger point pain. Interventions were required to be clearly described. 3.4. Types of outcome measures Studies that stated the use of subjective pain based outcome measures were included in the review. At least one patient-rated outcome measure such as pain intensity, frequency, duration or improvement was required from individual patients before and after administration of the study treatments. These measures included visual analogue scores for pain intensity or pain relief; categorical scores for pain intensity or pain relief; global ratings of treatment effectiveness as made by the study subjects. Studies that did not include subjective measures of either pain intensity or pain relief as part of the overall assessment of effectiveness, both before and after treatment, were excluded. 4. Data sources A systematic literature search was performed on 10th February 2005 to identify published randomised controlled trials examining non-invasive interventions in the treatment of myofascial pain syndrome arising from myofascial trigger points. The search was updated on 18th May 2006. The search was made over the following databases: Medline, PubMed, CINAHL, EMBASE, PEDro, and CENTRAL/CCTR. The search terms were as follows: key term e ‘trigger point’ OR ‘trigger points’; indexing terms e ‘randomised controlled trial’ OR ‘controlled clinical trial’. The key terms were searched for in the title, abstract and keywords. The search dates were from inception to the present. The reference lists of retrieved studies were scanned to identify additional relevant trials. Hand searching of the 1999 edition of Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual14 was also performed. 5. Data extraction The following data were extracted for each study: population; the inclusion and exclusion criteria; study

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design; randomisation; interventions used; blinding; description of dropouts; outcome measures; statistical analysis; results and conclusions. Included studies were assessed for internal validity and methodological quality using a critical evaluation instrument employed by Bronfort et al.30 in a review of non-invasive treatments for headache (Appendix A). The evaluation list contains 20 methodological items (AeT), of which 14 (BeG, J, LeN, and PeS) have been classified as internal validity items, and six (A, H, I, K, O, and T) as descriptive information items. The validity score (VS) is given as a percentage of the score of validity items, from a maximum of 14. The following levels of strength of evidence determined the results of the analysis: Significant evidence: consistent findings in multiple high quality (VS > 50) randomised controlled trials; Moderate evidence: consistent findings in multiple low quality trials (VS < 50) and/or a single relevant, high quality randomised controlled trial; Limited evidence: a single low quality randomised trial; Unclear evidence: inconsistent or conflicting results in multiple randomised trials; No evidence: no studies were identified; and Evidence of adverse effect: trials with lasting negative changes.

6. Description of studies The searches revealed 45 potentially relevant trials, 2231e52 of which were subsequently excluded (Table 1). Twenty-three studies met the inclusion criteria for this review. The included trials could be divided into five categories based on the type of intervention studied: laser therapies e six trials; electrotherapies e five trials; ultrasound e four trials; magnet therapies e three trials; and physical/manual therapies e five trials. There was some overlap of interventions between the categories. The methodological quality scores and the corresponding limitations for each trial are shown in Table 2. In many cases, even relatively high quality trials (VS > 50) had limitations that may have affected the interpretation of study results. Studies with lower validity scores are acknowledged as having substantial limitations. The characteristics of the included trials are outlined in Tables 3e7. Twenty of the twenty-three included trials assessed the treatment of MTrPs in the neck and/or upper trapezius region. In one of these trials (Snyder-Mackler et al.27) MTrPs in the lower back were also treated. Although Graff-Radford et al.53 report diagnosing MTrPs in the temporalis and masseter muscles, it is unclear as to whether these points were treated. Of the remaining three trials, Brown et al.54 assessed the treatment of

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Table 1 Excluded papers describing non-invasive therapies for MTrP pain Study

Reason for exclusion 31

Airaksinen and Pontinen Airaksinen et al.32 Airaksinen et al.33 Ceylan et al.34 Chee and Walton35 Curl and Emmerson36 Dardzinski et al.37 Fryer and Hodgson38 Hanten et al.39 Hong et al.40 Jaeger and Reeves41 Lewith and Machin42 Lundeberg43 McCray et al.44 Melzack45 Nilsson46 Pratzel47 Schnider et al.48 Simunovic49 Simunovic et al.50 Snyder-Mackler et al.51 Yagci et al.52

No criteria for diagnosis of MTrP No patient-rated outcome measures used No patient-rated outcome measures used, no MTrP criteria No patient-rated outcome measures used No outcome measures apparent Not randomised or blinded Not randomised or blinded Treatment of latent MTrPs No patient-rated outcome measures used No patient-rated outcome measures used Not randomised or blinded No criteria for diagnosis of MTrP Not specific to MTrP pain No criteria for diagnosis of MTrP, not limited to MTrP pain Not limited to MTrP pain Not specific to MTrP pain Not specific to MTrP pain Non-invasive therapy compared to invasive therapy only Not randomised Not specific to MTrP pain MTrPs diagnosed by skin resistance only No criteria for diagnosis of MTrP

MTrPs on the abdomen for chronic pelvic pain, Chatchawan et al.55 assessed the treatment of MTrPs in the upper and lower back, and Edwards and Knowles56 did not specify the region of treatment. 6.1. Laser therapies In general, the quality of trials assessing laser treatments for MTrP pain was high. Three types of lasers used were as follows: GaeAs57e59; HeeNe27,60; and infrared diode.61 In five of the six trials a significant statistical difference was found between the treatment and the placebo groups following treatment. Two trials57,61 reported that a significant effect persisted at a 3-month follow-up. Ilbuldu et al.60 measured outcomes at 6 months and found no difference between the treatment and the placebo groups. Altan et al.59 reported conflicting results, attributing the statistically significant effect in both the treatment and the placebo groups to a concurrent program of exercise and stretching. 6.2. Electrotherapies Five trials studied electrotherapies directly, and in two other trials (Hou et al.23 and Lee et al.62) electrotherapies were used as part of a mixed intervention protocol. There were five types of electrotherapies studied: transcutaneous

electrical nerve stimulation (TENS), electrical muscle stimulation (EMS), high voltage galvanic stimulation (HVGS), frequency modulated neural stimulation (FREMS), and interferential current (IFC). Five of the six trials used TENS. Hsueh et al.22 and Ardic et al.63 compared TENS with EMS, and in both papers TENS was superior to EMS in reducing pain. Lee et al.62 compared ultrasound with placebo ultrasound, TENS, and ultrasound plus TENS, and found that only TENS had a significant effect on pain intensity. Hou et al.23 reported a significant reduction in pain intensity where TENS or IFC was used in combination with other physical therapy modalities and/or manual techniques. Graff-Radford et al.53 compared four different modes of TENS and reported a superior effect on pain levels with 100 Hz, 250 ms stimulation. However, it is very difficult to base any solid conclusions of long-term treatment effectiveness on these results because in all but in one trial (Ardic et al.,63 which had a very low validity score) the final outcome assessment was immediately after treatment. Therefore, no evidence of medium- or long-term effectiveness is available. Smania et al.64 compared TENS with placebo US as part of a study examining repetitive magnetic stimulation and also found that TENS had an immediate effect, however, this did not persist at 1 month. Farina et al.65 compared TENS with FREMS. Although both treatments showed significant effect on pain scores and MTrP characteristics at 1 month, there was no difference between groups. The effect persisted at the final follow-up of 3 months for the FREMS group but not for the TENS group. Tanrikut et al.66 reported a significant reduction in pain intensity at 15 days (but not in analgesic usage) after the application of HVGS; however, the internal validity of this trial was poor. 6.3. Ultrasound In two of the four trials using ultrasound, which included one very high quality paper (Gam et al.67), ultrasound was reported to have no significant effect on pain. Esenyel et al.24 reported a superior effect, however, this study was of very poor quality and attention bias was a significant limitation. Lee et al.62 reported no significant difference between US and placebo US. Majlesi and Unalan68 compared high power pain threshold ultrasound (HPPT-US) with conventional ultrasound and reported a statistically significant reduction in pain intensity in the HPPT-US group. However, the validity score of this trial was also low. 6.4. Magnet therapies The three trials examining magnet therapies for MTrPs were of high quality. Brown et al.54 reported

Table 2 Methodological evaluation scores Graff- Smania Chatchawan Farina Fernandez et al. et al. de la Radford et al. (2005) (2005) (2004) Penas et al. et al. (1989) (2006)

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Informativeness items Defined þ inclusion and exclusion criteria Adequate p follow-up period Defined þ intervention protocol

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Validity items Group comparability Randomisation procedure Outcome measure Patient blinding Treatment provider blinding Unbiased outcome assessment Attention bias A priori hypothesis Appropriate statistical tests Adequate statistical power Dropout analysis Missing data analysis Intention-totreat analysis p-Level adjustments Total validity score (%)

Ardic Hsueh Gur Tanrikut Ilbuldu Majlesi Edwards Ceccherelli Snyder- Hakguder Smania Altan Brown Hanten Esenyel Hou Gam Lee et al. Mackler et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. and (2003) et al. (2003) (2003) (2002) (2000) (2000) (2002) (1998) (1997) (2002) (1997) (2004) (2003) (2004) (2004) Knowles (1989) (1989) (2003)

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a superior effect over placebo using magnets taped to MTrPs on the abdomen for the treatment of chronic pelvic pain. Although this study had a high validity score patient blinding was shown to be compromised. Smania et al.2 reported that repetitive magnetic stimulation (rMS) technique was superior to placebo in reducing pain from MTrPs in the upper trapezius muscle, however, this was a very small study, with only nine patients in each group. In a later study, Smania et al.64 repeated the rMS treatment with a larger population (although the required statistical power was not established) and found significant changes in outcomes up to 3 months following treatment when compared with TENS and placebo US.

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Smania Altan Brown Hanten Esenyel Hou Gam Lee Ardic Hsueh Gur Tanrikut Ilbuldu Majlesi Edwards Ceccherelli Snyder- Hakguder et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. et al. and et al. Mackler et al. (2003) (2003) (2002) (2000) (2000) (2002) (1998) (1997) (2002) (1997) (2004) (2003) (2004) (2004) Knowles (1989) et al. (2003) (2003) (1989)

Table 2 (continued )

Graff- Smania Chatchawan Farina Fernandez Radford et al. et al. et al. de la et al. (2005) (2005) (2004) Penas (1989) et al. (2006)

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Hou et al.23 studied various combinations of exercise, manual therapy, stretching and modalities. In this study, all groups that received some form of electrotherapy modality had a superior effect on pain intensity compared to the control group. The combination of hot pack, range of motion exercise, IFC and myofascial release showed the largest reduction in pain. However, the final follow-up in this trial was 5 min after treatment. Hanten et al.69 studied the effects of a home program of self-applied ischemic compression followed by stretching compared to active range of motion exercises, and found a statistically significant difference in pain intensity for the home program group, but no difference in total time in pain. The follow-up in this trial was only 3 days. Edwards and Knowles56 reported no difference in pain scores between the stretching group and the no treatment control group after 3 weeks, however, this trial was of poor methodological quality. Gam et al.67 also used massage and exercise in both the US treatment and the placebo US groups and made comparisons with a no treatment control group. No significant difference in pain intensity or analgesic use was measured between any of the groups at any time. However, significant reduction in the MTrP characteristics was noted for both groups that received massage and exercise. Chatchawan et al.55 compared Thai massage plus stretches with Swedish massage plus stretches. This was a very well conducted study, although no control was used. Both groups showed significant reductions in pain and disability measures, however, there was no difference between the groups. Fernandez de la Penas et al.70 compared ischemic compression with transverse friction massage and found a significant reduction in pain intensity for both groups but no difference between the groups. However, no conclusion regarding medium to long-term effectiveness can be drawn as the only outcomes measurement was immediately after treatment.

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Table 3 Laser therapies for trigger points Study 57

Gur et al.

VS Diagnosis

n

68 Chronic MPS in the neck

60

Snyder-Mackler 68 MPS in the neck 24 et al.27 or lower back

Ceccherelli et al.61 Hakguder et al.58

50 MPS the neck

Ilbuldu et al.60

38 Trigger points in 60 upper trapezius muscle

Altan et al.59

46 MPS in the neck 53

27

55 MPS in the neck 62 or upper back

Intervention/control A: GaeAs LLLT; B: placebo GaeAs LLLT

A: HeeNe cold laser; B: placebo HeeNe cold laser

Outcome measures

FU Result

Neck pain and disability scale, VAS, Beck depression inventory, Nottingham health profile, n TrP Pain VAS, Skin resistance (dermometer)

3 m A superior to B; ( p < .01) on all measures

1 d A superior to B; pain ( p < .005). No correlation between pain and skin resistance A: infrared diode laser; Pain VAS, McGill pain 3 m A superior to B; MPQ B: placebo infrared diode laser questionnaire (MPQ) ( p < .008), pain ( p < .001) A: GaeAseAl LLLT and Pain VAS, pain threshold 3 w A superior to B; pain stretching; algometry, thermographic ( p < .001), pain threshold B: placebo GaeAseAl LLLT asymmetry and difference ( p < .001), thermography e and stretching asymmetry ( p < .001)/ difference ( p < .01) A: HeeNe laser; Pain VAS (rest and activity), 6 m A superior to B and C B: dry needling; Pain threshold algometry, post-treatment: pain C: placebo HeeNe laser; Cervical range of motion, ( p < .001), ROM ( p < .001), All groups: trapezius and Nottingham health profile NHP e pain ( p < .001)/phys pectoralis stretches (NHP) activity ( p < .05). A equal to B and C at 6 months FU A: GaeAs LLLT þ exercise Pain VAS, pain threshold 3 m A equal to B; significant and stretching; algometry, cervical lateral improvement in both groups B: placebo GaeAs LLLT þ flexion range attributed to exercise/stretching exercise and stretching

VS, validity score; FU, follow-up; n, number treated; MPS, myofascial pain syndrome; LLLT, low level laser therapy; and VAS, visual analogue scale.

7. Data synthesis Although this review only included trials that were explicit regarding the diagnostic characteristics of MPS, it is significant that only three of the 23 trials that met this inclusion criteria documented changes in the these diagnostic characteristics as part of the outcome assessment. Each of these trials used an index described by Gam et al.67 All the three trials64,66,67 reported statistically significant reductions in the taut band and spot tenderness. However, without more extensive evidence that changes in the clinical characteristics of the MTrP occur following treatment it is unclear whether treatment effectively addresses the entity by which diagnosis is made or positive outcomes are due to other factors. The clinical uncertainties surrounding MTrP diagnosis also present many challenges. Although Gerwin et al.20 have successfully demonstrated interrater reliability that the presence of an MTrP can be generally identified, Sciotti et al.10 point out that the routine ability to obtain precise location dimensions of MTrPs with actual visualisation, such as 3D measurement techniques, is essential to the establishment of reliable data on pathogenesis, clinical diagnosis, and treatment. Until this is achieved and implemented in clinical trials assessing treatments for MTrP pain reliable evidence of treatment effectiveness will remain elusive.

The results of this review highlight a considerable discrepancy between the vast range of non-invasive treatments given for MPS and those supported by the literature. Most of the treatments have not been subjected to clinical trial, thus no evidence of effectiveness is available. Of those that have been studied, the evidence for effectiveness must be considered preliminary due to the paucity of explicit clinical trials to date. It is also important to remember that most of the current evidence on the treatment of MTrPs is limited to the upper trapezius and cervical regions. Any positive effects of treatment must also be interpreted in light of the issues discussed above. According to the results of this review there is a significant evidence that laser therapy may be effective as a short-term intervention for reducing pain intensity in myofascial trigger point pain of the neck and upper back. Further research is necessary to determine the long-term effectiveness, the most effective type of laser, and the optimum dosage, duration and frequency of treatment. TENS appears to have an immediate effect in decreasing pain intensity in myofascial trigger point pain of the neck and upper back. However, there are insufficient data to determine the effectiveness for TENS beyond immediately after treatment. There is limited evidence for the use of FREMS, HVGS, EMS and IFC for

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Table 4 Electrotherapies for trigger points Study

VS Diagnosis

Graff-Radford et al.53

59

Chronic MPS in the 60 back, neck or head

Farina et al.65

61

Trigger point pain in upper trapezius on one side

40

Hsueh et al.22

60

Trigger point pain in upper trapezius on one side

60

Ardic et al.63

25

Trigger point pain in upper trapezius on one side

40

MPS the neck or upper back

45

Tanrikut et al.66 28

n

Intervention/control A: TENS modeA; B: TENS modeB; C: TENS modeC; D: TENS modeD; and E: placebo TENS A: FREMS B: TENS

A: placebo electrotherapy B: TENS C: EMS A: TENS and trapezius stretching B: EMS and trapezius stretching C: Trapezius stretching A: HVGS and exercise B: placebo HVGS and exercise C: exercise

Outcome measures

FU

Result

Pain VAS, pain threshold 5 min B superior to C and D. C and D algometry superior to A and E; pain ( p < .001) (B ¼ 100 Hz, 250 ms). Pain threshold e all groups equal NDPVAS, pain threshold 3 m algometry, cervical range of motion (ROM), MTrP characteristics

Significant effect of FREMS on at 3 months; NDPVAS ( p < .001). Significant effect of TENS on at 1 month; NDPVAS ( p < .001). No significant difference between groups Pain VAS, pain threshold 5 min B superior to A and C; pain and algometry, cervical range threshold ( p < 0.05). C superior to of motion (ROM) B and C; ROM ( p < 0.05) Pain VAS, pain threshold 3 m algometry, cervical range of motion (ROM)

A equal to B, A and B superior to C; pain and threshold ( p < .01). A superior to B immediately after treatment ( p < .01)

Pain VAS, analgesic use, patient global assessment

A superior to B and C; pain ( p < .05), global ( p < .05). A equal to B and C; analgesic use

15 d

EMS, electrical muscle stimulation; TENS, transcutaneous electrical nerve stimulation; HVGS, high voltage galvanic stimulation; and FREMS, frequency modulated neural stimulation.

myofascial trigger point pain. This conclusion reflects the results of a recent Cochrane review of electrotherapies for neck disorders that concluded the current evidence for electrotherapies either lacking, limited, or conflicting.71 Moderate evidence derived from one high quality and two lower quality studies indicate that conventional ultrasound is no more effective than placebo or no treatment for myofascial trigger point pain in the neck and upper back. Further research is needed to evaluate the effectiveness of high power pain threshold ultrasound.

Although the three trials researching magnet therapy were generally of good quality, there were a number of significant flaws. Thus the level of evidence must be considered moderate. Further studies are needed to support the findings of these trials. The contraindications of magnet therapies and minor adverse effects reported in one of the studies must also be considered. Due to the heterogeneity of trials examining physical and manual therapies the current evidence did not exceed the moderate level. Further, most of these trials examined multimodal treatment programs, so the

Table 5 Magnet therapies for trigger points Study 54

Brown et al.

VS Diagnosis

n

82

33

Chronic pelvic pain with presence of trigger points

Smania et al.64 71

Trigger point pain in 53 upper trapezius

Smania et al.2

Trigger point pain in 18 upper trapezius

64

rMS, repetitive magnetic stimulation.

Intervention/control

Outcome measures

FU Result

A: Active 500 g magnets McGill pain questionnaire, 1 m A superior to B; PDI ( p < .05), B: placebo magnets pain disability index (PDI), CGI-severity ( p < .05), CGIclinical global impressions improvement ( p < .01). Blinding (CBI) possibly compromised ( p < .05) A: rMS Pain disability NPDVAS, 3 m A superior to B; pain ( p < .001), B: TENS pain threshold algometry, pain threshold ( p < .001), MTrP C: placebo US with gel MTrP characteristics characteristics ( p < .001). B cervical range of motion superior to C immediately after (ROM) treatment; pain ( p < .001) A: rMS Pain VAS, pain disability 1 m A superior to B; pain ( p < .022), B: placebo rMS NPDVAS, pain threshold pain disability ( p < .016), pain algometry, cervical range threshold ( p < .016). A equal to of motion (ROM) B; ROM ( p < .066)

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L.D. Rickards / International Journal of Osteopathic Medicine 9 (2006) 120e136 Table 6 Ultrasound therapies for trigger studies Study

VS Diagnosis 67

Gam et al.

71 Chronic MPS in the neck or shoulder

Majlesi and Unalan68 46 Trigger point pain in upper trapezius on one side Lee et al.62 27 Trigger point pain in upper trapezius Esenyel et al.24

25 Trigger point pain in upper trapezius on one side

Intervention/control

n 67

72

26

102

Outcome measures

FU

Result

A: US, massage and exercise; B: placebo US, massage and exercise; C: control A: HPPT-US B: conventional US

Pain VAS, MTrP characteristics, daily analgesic use

6m

A equal to B equal to C; analgesic use and VAS; A and B superior to C; MTrP characteristics

Pain VAS, cervical range of motion

4w

A: placebo US; B: US; C: electrotherapy; D: US and electrotherapy A: US and neck stretches B: TrP injection and neck stretches C: neck stretches

Pain VAS, pain threshold algometry, cervical range of motion

A superior to B; pain ( p < .05). A equal to B; ROM ( p > .05) 5 min C superior to A; pain ( p < .05). D superior to A, B, C; ROM ( p < .05)

Pain VAS, pain 3m threshold algometry, cervical range of motion, Beck depression inventory Taylor manifest anxiety sc

A and B superior to C; pain ( p < .001) pain threshold ( p < .001), ROM ( p < .05). A equal to B. Anxiety > depression in MPS. Correlation between depression/anxiety and pain duration but not intensity

US, ultrasound; HPPT-US, high power pain threshold ultrasound.

presence of positive effects cannot be attributed to a particular approach. The four higher quality trials55,67,69,70 examining manual techniques suggest that such approaches may be effective, however, no conclusions regarding medium to long-term effectiveness can be drawn. Additionally, effectiveness beyond placebo is neither supported nor refuted. Larger, high quality trials with longer follow-up periods are needed to support the findings of these studies.

8. Discussion Although it is commonly argued that the long-term relief of MTrP pain must involve consideration of all contributing or perpetuating factors,7,18,22,69,72 none of the trials included in this review carefully addressed these issues or controlled for such factors. Travell and Simons7 suggest the following as perpetuating factors for MTrP pain: mechanical stress, such as poor posture

Table 7 Physical and manual therapies for trigger points Study

VS Diagnosis 55

n

Intervention/control

Chatchawan et al.

85 Back pain with at least 180 one MTrP in the upper or lower torso

A: Traditional Thai massage þ stretches B: Swedish massage þ stretches

Fernandez de la Penas et al.70

72 Trigger point pain in upper trapezius

40

A: IC B: TFM

Hanten et al.69

68 MPS in the neck or upper back

40

Hou et al.23

50 Trigger point pain in upper trapezius

119

Edwards and Knowles56

41 MPS, region unspecified 40

A: home program e IC followed by sustained stretching B: active range of motion exercises A: HtP and AROM; B: A þ IC; C: A þ IC and TENS; D: A þ SwS; E: A þ SwS and TENS; F: A þ IFC and MFR A: superficial dry needling and stretching; B: stretching; C: no treatment control

Outcome measures

FU

Result

VAS, Oswestry Disability 1 m VAS and ODI reduced Index, Pain threshold by half ( p < .05) in both algometry, Thoracolumbar groups. No significant ROM difference between groups Pain VAS, pain threshold 2 min Significant effect of A and algometry B on VAS ( p < .05). A equal to B ( p < .05); VAS Pain VAS, pain threshold 3 d A superior to B; pain algometry, percentage of ( p ¼ .043), pain threshold time in pain ( p ¼ .000). A equal to B for time in pain Pain VAS, pain tolerance pain threshold algometry, cervical range of motion

5 min C, D and F superior to A; pain ( p < .05) D, E and F superior to A; ROM ( p < .05) B, C, D, E, F equal. F; largest VAS Y

Short form MPQ, pain threshold algometry

3w

A superior to C; MPQ ( p < .05). B equal to C

IC, ischemic compression; TFM, transverse friction massage; HtP, hot pack; AROM, active range of motion exercise; SwS, stretch with spray; IFC, interferential current; and MFR, myofascial release.

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or muscle injury; nutritional inadequacies; metabolic or endocrine disorders; allergies; impaired sleep; psychological factors; chronic infection; radiculopathy; chronic visceral disease. Many of these factors are controllable. In a cohort study of 25 chronic myofascial head and neck pain patients, Graff-Radford et al.73 examined the use of a structured interdisciplinary format of physical and cognitive behavioural therapies aimed at reducing factors that perpetuate myofascial pain. The results immediately following treatment, and at 3, 6 and 12 months post-treatment showed highly reliable reductions in self-reports of pain and medication intake when compared to pre-treatment scores. However, there are no randomised controlled trials that address the duration of pain relief associated with the management of contributing and perpetuating factors.69 In a study investigating factors that may influence the outcome of trigger point injection therapy, Hopwood and Abram74 found that an increased risk of treatment failure was associated with unemployment due to pain at the start of treatment, no relief from analgesic medication, constant pain, high levels of pain-at-its-worst and pain-at-its least, prolonged duration of pain, change in social activity, lower levels of coping ability, and alcohol use. The researchers concluded that several factors should be considered in treating myofascial pain patients with trigger point injections. This study supports the belief that pain is a multidimensional problem and that a variety of factors may influence the treatment outcome. This view was supported in a recent review of MPS by Graff-Radford,75 suggesting that the pathogenesis of myofascial pain likely has a central mechanism with peripheral clinical manifestations. Therefore, therapy for myofascial pain should involve enhancing central inhibition with pharmacology or behavioural and psychological techniques and concurrently reducing peripheral inputs with physical therapies, including exercises and trigger point-specific therapy.75 Finally, it is worth noting that Quintner and Cohen76 have criticised the entire myofascial trigger point construct as the result of circular reasoning and suggested that the emphasis on the primacy of the MTrP phenomenon has directed attention away from other possible explanations. They argue that there are anatomical and physiological grounds to indicate that the phenomenon of the MTrP, on which the theory of MPS depends, is better understood as a region of secondary hyperalgesia of peripheral nerve origin. This is also supported by Butler77 who suggests that the concept of ectopic impulse generation, or abnormal impulse generating sites (AIGS), in peripheral and cutaneous sensory nerves compels reconsideration of the myofascial trigger point hypothesis. In contradiction, Partland16 has stated that it is in fact that the pathological mechanisms of the MTrP that cause the development of peripheral nerve sensitisation and AIGS, although Butler77 is cited as

the source. Neither claims have yet been verified or refuted. 8.1. Limitations of the review Publication bias was a limitation in this review. Optimally, reviews should include all trials, including unpublished research, regardless of language.78 Due to resource and language constraints, only English language publications were included in the review and no effort was made to identify unpublished trials (other than those held in the CENTRAL database). However, it is also recognised that unpublished data can be a source of bias.79 The methodological quality of the included trials is usually assessed by two or more reviewers.80 Unfortunately, methodological quality assessment was conducted by one reviewer only. Assessment was also unblinded. Although there is some evidence that blinded assessments of the quality of trials may be more reliable than assessments that are not blinded,81 blinding can be difficult to achieve, is time consuming and may not substantially alter the results of a review.82 In addition, the reliability of different methodological scoring systems may be a source of ambiguity. Conclusions regarding the weight of evidence are dependent on the choice of methodological quality scoring system and on the exact definition of the evidence classification system used.30,83 Therefore, as suggested by Bronfort et al.,30 a commonly used methodological assessment tool, the five-point scoring system developed by Jadad et al.81 (Appendix B) was used in addition to the 20item scale described above. The Jadad system addresses randomisation, double-blinding, and description of dropouts, all of which may be important sources of bias if addressed inadequately. However, the correlation between the total scores of the two scoring systems was low. The explanation for this is the proportionally high weight placed on the importance of blinding both the patient and the therapist in the Jadad scale compared to the 20-item scale. Complete blinding for many physical treatments (e.g., exercise and manual therapies) is difficult or impossible to achieve.84 Consequently, the validity scores derived from the Jadad scale were excluded from the data analysis. 8.2. Magnitude of effects When interpreting the results of randomised controlled trials, a distinction must be made between statistically significant results and clinically significant results.30,85 Inappropriate conclusions are commonly drawn when treatment efficacy is based solely on the presence or absence of statistical differences between a test treatment group and a control group.32,86 If the statistical output has proved to be statistically

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significant, then the results cannot be automatically interpreted as clinically significant.85,86 To inform decisions about the management of individual patients, it may be more appropriate to consider available treatment options which have shown a meaningful clinical effect, rather than choosing or discarding specific therapies based on the difference between-group means of undefined clinical importance.30 Unfortunately, however, little is known about what is considered by patients to be a minimal clinically important change in myofascial pain related outcome measures.86 8.3. Previous systematic reviews Only four published systematic reviews have assessed the effect of different non-invasive therapies for myofascial pain. Hey and Helewa87 reported that in many studies a lack of validated diagnostic criteria contributed to confusion between MPS and other chronic pain syndromes. None of the treatments reviewed were shown to be efficacious. Fernandez de la Penas et al.88 reviewed the evidence for manual therapies in the treatment of MTrPs. The review concluded that although a number of studies demonstrate statistically significant reductions in pain scores and pressure sensitivity, the current evidence neither supported nor refuted effectiveness beyond placebo. Two reviews have been published on laser treatments for MPS, however, these are now outdated. Beckerman et al.89 reported in a meta-analysis that trials supporting a positive effect of LLLT had higher methodological quality, and LLLT was effective for MPS. On the other hand, in another meta-analysis, Gam et al.90 suggested that the efficacy of LLLT was found to be lower in double-blind trials when compared with the uncontrolled ones, and that LLLT was ineffective for MPS.

9. Conclusions

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the suggestion that myofascial pain syndrome should be considered a multidimensional problem that requires a structured multimodal approach to treatment.

9.2. Implications for research Further high quality trials are needed to establish a firmer basis for considering these treatments as viable options. The clinical effectiveness of the commonly used therapies for which there is some evidence of effect needs to be researched further. Trials should document the diagnostic criteria and precise location of myofascial trigger points and changes in the diagnostic characteristics of MPS should be included in the outcomes measurement. Where possible, contributing and perpetuating factors should be controlled. Greater attention should also be paid to randomisation procedures and ensuring adequate statistical power as these were consistently weak throughout the included trials. To better inform decisions about patient management, trials should evaluate and document not only the differences between group means, but also the distribution of clinical values or outcomes within each treatment group.30

Appendix A. Critical evaluation list of methodological quality The following is a description of each item in the list, accompanied by operational definitions: A. Are the inclusion and exclusion criteria clearly defined? (Information item) YES: Inclusion and exclusion criteria are stated explicitly. UNCLEAR/PARTLY: Inclusion and/or exclusion criteria are not clearly defined. NO: Inclusion/exclusion criteria are not described.

9.1. Implications for practice The evidence for effectiveness of the different non-invasive interventions for myofascial trigger point pain rests only on small groups of separate trials, or in some cases on an individual trial. Even where trials were generally of good quality, consideration must be given to the presence of significant flaws. Thus the strength of evidence should be considered limited in most cases. The heterogeneity of the included trials means that the conclusions of this review could be easily influenced by the results of a few additional high quality trials in the future. A few of the treatments studied may be effective, however, it is unknown whether they actually address the proposed pathological entity or some other processes. Greater attention should be given to

B. The groups are comparable at baseline, or if different, are appropriate adjustments for confounding made in the statistical analysis? (Validity item) YES: Comparability is established by tabulating important predictor variables, including baseline value of main outcome, demographic variables, duration and severity of condition, and other known prognostic indicators such as patient expectations. If comparability is not established, then analysis of co-variance or equivalent is used. UNCLEAR/PARTLY: Baseline comparability is established for some, but not all, of the important predictor variables. NO: Baseline comparability is not established and appropriate statistical adjustments are not made.

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C. Is the randomisation procedure adequately described and appropriate? (Validity item) YES: The randomisation process is described (e.g., randomly generated list, opaque envelopes), and the method used (simple, block, stratification, minimisation, etc.) is appropriate, and allocation concealment is established explicitly. UNCLEAR/PARTLY: One or two of the aforementioned three criteria are met. NO: Information given indicates that randomisation was used, but none of the aforementioned three criteria are met. D. Is it established that at least one main outcome measure was relevant to the condition under study, and were adequate reliability and validity established? (Validity item) YES: At least one of the primary outcomes is patientoriented (e.g., pain, functional disability), and its reliability and validity documented or generally accepted. UNCLEAR/PARTLY: Documentation of reliability or validity are absent for an outcome measure that is not generally accepted. NO: Neither relevance, reliability, nor validity is established. E. Are patients blinded to the degree possible, and did the blinding procedure work? (Validity item) YES: Optimal blinding is used and effectiveness of the blinding procedure is documented. UNCLEAR/PARTLY: Either optimal blinding or effectiveness of blinding is not documented. NO: Neither optimal blinding nor its effectiveness is documented. NOT APPLICABLE: Trial may not be blindable (e.g., a comparison of a drug and a physical treatment). F. Is it established that treatment providers were blinded to the degree possible, and did the blinding procedure work? (Validity item) YES: Optimal blinding is used and effectiveness of the blinding procedure is documented. UNCLEAR/PARTLY: Either optimal blinding or effectiveness of blinding is not documented. NO: Neither optimal blinding or effectiveness of blinding is documented. NOT APPLICABLE: Trial may not be blindable (e.g., a comparison of a drug and a physical treatment). G. Is it established that assessment of the primary outcomes was unbiased? (Validity item) YES: Subjects were not influenced by study personnel. It is established that assessors were blinded, when relevant.

UNCLEAR/PARTLY: Unclear or no documentation of unbiased assessment of outcomes. NO: It is established or highly likely that patients were influenced by providers or investigators on how they scored their own outcomes, or it is not established that an assessor was blinded when applicable. H. Is the post-intervention follow-up period adequate and consistent with the nature of the condition under study? (Information item) YES: Minimal acceptable post-intervention followup period for acute conditions is 1 month and for chronic conditions 3 months. UNCLEAR/PARTLY: A minimum of 2 weeks postintervention follow-up period for acute conditions and 1 month for chronic conditions. NO: Shorter than 2 weeks post-intervention followup period for acute conditions and 1 month for chronic conditions. NOT APPLICABLE: May not apply to study (e.g., crossover designs). I. Are the interventions described adequately? (Information item) YES: All interventions follow a defined protocol. It is possible from the description in the article or reference to prescribe or apply the same treatment in a clinical setting. UNCLEAR/PARTLY: Unclear or incomplete description of one or more of the interventions. NO: Very inadequate or no description of one or more of the interventions. J. Were differences in attention bias between groups controlled for and explicitly described? (Validity item) YES: Documentation that time, provider enthusiasm, and number of intervention sessions are equivalent among study groups. UNCLEAR/PARTLY: No documentation that time, provider enthusiasm, and number of intervention sessions are equivalent among study groups. NO: Evidence that time, provider enthusiasm, and number of intervention sessions are clearly not equivalent among study groups. NOT APPLICABLE: Pragmatic trials. K. Is comparison made to existing efficacious or commonly practiced treatment options? (Information item) YES: Comparison is made to existing efficacious or commonly practiced treatment options. UNCLEAR/PARTLY: Equivocal information. NO: Comparison is not made to existing efficacious or commonly practiced treatment options. NOT APPLICABLE: Placebo-controlled and nonmanagement trials.

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L. Is the primary study objective (hypothesis) clearly defined a priori in terms of group contrasts, outcomes, and time points? (Validity item) YES: The primary study objective (hypothesis) is clearly defined a priori in terms of group contrasts, outcomes, and time points. UNCLEAR/PARTLY: The primary study objective (hypothesis) is only partially defined a priori. Information is lacking about group contrasts, outcomes, or time points. NO: The primary study objective (hypothesis) is not defined a priori in terms of group contrasts, outcomes, or time points. M. Is the choice of statistical tests of the main results appropriate? (Validity item) YES: The main analysis is consistent with the design and the type of the outcome variables used. UNCLEAR/PARTLY: The main analysis is not clearly described or only partially consistent with the design and the type of the outcome variables used. NO: The main analysis is clearly inconsistent with the design and/or the type of the outcome variables used. N. Is it established at randomisation that there is adequate statistical power (1-beta ¼ 0.8, with alpha ¼ 0.05) to detect an a priori determined clinically important between-group difference of the primary outcomes, including adjustment for multiple tests and/or outcome measures? (Validity item) YES: Adequate statistical power documented. NO: No documentation of adequate statistical power. O. Are confidence intervals or data allowing confidence intervals to be calculated presented? (Information item) YES: Confidence intervals are presented or can be calculated. UNCLEAR/PARTLY: Confidence intervals are presented or can be calculated for only some of the main outcomes. NO: Confidence intervals are not presented and cannot be calculated from available data. P. Are all dropouts described for each study group separately and accounted for in the analysis of the main outcomes? (Validity item) YES: Analysis of impact of dropouts or worst-/bestcase analysis reported. UNCLEAR/PARTLY: Incomplete analysis of impact of dropouts. NO: Analysis of impact of dropouts not performed or reported. NOT APPLICABLE: Dropout rate less than 5%.

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Q. Are all missing data described for each study group separately and accounted for in the analysis of the main outcomes? (Validity item) YES: Analysis of impact of missing data reported. UNCLEAR/PARTLY: Incomplete analysis of impact of missing data. NO: Analysis of impact of missing data not performed or reported. NOT APPLICABLE: Missing data less than 5%. R. If indicated, was intention-to-treat analysis used? (Validity item) YES: All patient data analysed according to group or initial random allocation. In studies with documented full compliance with allocated treatments and no differential co-intervention between groups, a YES score can apply. UNCLEAR/PARTLY: Unclear from article whether intention-to-treat analysis was used and how. NO: No intention-to-treat analysis used when applicable. NOT APPLICABLE: Single-session studies (e.g., studies with one intervention and outcomes collected in same session). S. Were adjustments made for the number of statistical tests (two or more) when establishing a cut-off point for p-level for each test? (Validity item) YES: Appropriate adjustments made. UNCLEAR/PARTLY: Insufficient adjustment or lack of adequate information about adjustment. NO: Adjustments were indicated but not performed. NOT APPLICABLE: Indicated adjustments were incapable of changing main result/outcome of study, or study involved only one test at one time point. T. Are the main study conclusions valid? (Information item) YES: A priori testable hypotheses are tested and prioritised appropriately in the conclusions. UNCLEAR/PARTLY: A priori testable hypotheses are only partially tested and/or prioritised appropriately in the conclusions. NO: A priori testable hypotheses are not tested and prioritised appropriately in the conclusions.

Appendix B. The Jadad scale The Jadad et al.26 criteria and scores are as follows: 1a:

Was the study described as randomised? (Score 1 if yes);

1b and 1c: Was the method of randomisation described and appropriate to conceal allocation? (Score 1 if appropriate and 1 if not appropriate);

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2a:

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Was the study described as double-blinded? (Score 1 if yes);

2b and 2c: Was the method of double-blinding described and appropriate to maintain double-blinding? (Score 1 if appropriate and 1 if not appropriate); 3: Was there a description of how withdrawals and dropouts were handled? (Score 1 if yes)

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