Description of the condition
Stroke is a leading source of acquired disability and has potentially enormous emotional and socioeconomic consequences for patients, their families and health services (Feigin 2003). There are two main causes of stroke: haemorrhagic stroke resulting from a ruptured blood vessel inside brain, and ischaemic stroke caused by vascular insufficiency (such as cerebrovascular thromboembolism). With the worldwide population ageing, the burden of stroke will increase in the next 20 years (Donnan 2008). Despite the rapid progress in medical science, there are limited effective interventions for people with acute stroke (Langhorne 2009). Consequently, the management strategy for most people with stroke remains secondary prevention and rehabilitation (Quinn 2009). Of those who survive the acute stroke, about 50% will still experience some level of disability after six months (Wade 1987). Therefore, stroke has become a severe public health problem worldwide.
A number of therapies in development aim to improve patient outcomes and any intervention that enables people to recover more rapidly or gain functional independence would have major benefits for them and their families. In addition, brain recovery and rehabilitation will also be a prioritised field in future stroke research (Hachinski 2010). There is a lot of evidence that some therapies, such as functional electrical stimulation (FES) (Glanz 1996; Price 2000) and constraint-induced movement therapy (CIMT) (Sirtori 2009; Wolf 2006; Wolf 2008), can improve motor function and quality of life when used in rehabilitation after stroke.
Description of the intervention
The effect of vibration stimuli on the nervous and muscular system has been studied in different fields (Cardinale 2003; Goetz 2009) and has evolved into full body training known as whole-body vibration (WBV). WBV therapy involves placing the individual (using static position or dynamic exercises, or both) on an oscillating platform that generates a specific frequency and amplitude of mechanical vibrations. It generates an oscillatory vertical motion (vertical platform) or a movement around a horizontal axis (oscillating platform) (Marín 2010). The contact surface of the platform transmits a vibration (in feet or hands) throughout the body. There is another Cochrane Review of WBV therapy that describes its effectiveness and the methodological weakness of randomised controlled trials (RCTs) in neurodegenerative disease (Sitjà Rabert 2012).
How the intervention might work
The seesaw-like displacement of the WBV platform is reported to mimic human gait (Schyns 2009). WBV can activate the Ia and II afferents of (large) muscle groups (Nardone 2001; Roll 1989) and induce sensory stimulation of foot-sole afferents (Kavounoudias 1999; these afferents are well known to play an important role in postural control (Meyer 2004)). The vibration signals of the WBV platform activate the muscle spindles in the leg musculature, which in turn induces reflexive activation of the motor units (Pang 2006) and increases their synchronisation (Cardinale 2003; Kossev 2001). Muscular vibration has contralateral effects on motor cortex excitability, suggesting transcallosal motor-evoked potential modulation (Kossev 2001), which could be especially important in people with stroke (Chollet 1991).
Why it is important to do this review
The effects of WBV therapy on posture and motor symptoms have also been examined in other clinical conditions including people with Parkinson's disease (Haas 2006; Turbanski 2005), cerebral palsy (Ahlborg 2006; Semler 2007) and multiple sclerosis (Schuhfried 2005). Although there are published studies of the clinical efficacy of WBV therapy on function recovery in stroke patients, its potential therapeutic effect has been inconclusive (Brogardh 2012; Chan 2012; Lau 2012; Merkert 2011; Tihanyi 2007; Tihanyi 2010; van Nes 2006). The reason for doing this review is that, in principle at least, WBV therapy might also do harm: if it is ineffective, it is wasting resources, if it is effective, it is a relatively simple way to assist stroke patients in their recovery. The aim of this review is to assess systematically all RCTs of WBV therapy on functional recovery in people with stroke to provide the best evidence and further research planning for stroke treatment. At the same time, we also expect to have a statement regarding when and how often WBV therapy should be used in practice.
To assess the efficacy and safety of WBV therapy for improving activities of daily living and qualify of life in people with stroke.
Criteria for considering studies for this review
Types of studies
We will include RCTs in which the study authors compare WBV therapy with sham therapy or another exercise programme.
Types of participants
We will include studies with participants of any age or sex after stroke (ischaemic or haemorrhagic), regardless of the duration of illness or severity of the initial impairment. The clinical definition of stroke will use the World Health Organization criteria (Stroke 1989).
Types of interventions
We will include all trials that evaluate WBV therapy in people with stroke regardless of age, duration of illness, session duration or device manufacturers. The control interventions will include sham treatment, other exercise programmes or conventional treatment.
Types of outcome measures
We will assess outcomes at the end of the treatment period and at every scheduled follow-up.
Dependency, assessed by any scales with reported validated studies, such as the modified Rankin Scale (mRS), Care Dependency Scale (CDS), Functional Independence Measure (FIM), Barthel index (BI) or modified Barthel Index (mBI). We will define dependency as severely dependent on others in activities of daily living, for example a BI score of 60 or less, the mRS graded 3 to 5, or the trialists' own definition.
We will also assess the following outcomes.
- Changes in impairment. This would include muscle strength (e.g. maximum isometric and eccentric torque, rate of torque development, root-mean-squared EMG, median frequency of vastus lateralis, co-activation of knee flexors, the Motricity Index); muscle tone (modified Ashworth Scale); ankle spasticity (visual analogue scale); postural control (limit-of-stability test); trunk stability (e.g. functional test of the lower back, Trunk Control Test); fall-related self efficacy (activities-specific balance confidence scale); health-related quality of life (HRQoL); any other impairment improvement (e.g. visual, perceptual, etc).
- Changes in activities, or functional activities. This would include measures of mobility (e.g. six-minute walk test, 10 metre walk test and cadence, Rivermead Mobility Index); balance (e.g. Berg Balance Scale); gait performance (e.g. timed up and go test, comfortable gait speed, fast gait speed, Tinetti Gait Test), Functional Ambulation Categories.
- All adverse events (e.g. seizures, headaches, dizziness, etc).
Search methods for identification of studies
See the 'Specialized register' section in the Cochrane Stroke Group module. We will search for relevant trials in all languages and arrange translation of trial reports published in languages other than English.
We will search the Cochrane Stroke Group Trials Register, the Chinese Stroke Trials Register and the following electronic bibliographic databases:
- the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, latest issue);
- MEDLINE (1950 to present) (Appendix 1);
- EMBASE (1980 to present);
- ISI Science Citation Index (1981 to present);
- CINAHL (1982 to present);
- AMED (the Allied and Complementary Medicine Database (1985 to present);
- SportDiscus (1949 to present)
- PEDro (Physiotherapy Evidence Database) (http://www.pedro.org.au/);
- REHABDATA (http://www.naric.com/?q=en/REHABDATA);
- CIRRIE Database of International Rehabilitation Research (http://cirrie.buffalo.edu/index.html);
- the China Biological Medicine Database (CBM) (1978 to present);
- the Chinese National Knowledge Infrastructure (CNKI) (1979 to present);
- Chinese Science and Technique Journals Database (VIP) (1989 to present);
- Wanfang Data (http://www.wanfangdata.com/) (1984 to present).
We developed the MEDLINE search strategy with the help of the Cochrane Stroke Group Trials Search Co-ordinator and will adapt it for the other databases.
We will also search:
- the following international trials registers: ClinicalTrials.gov (http://www.clinicaltrials.gov/); Current Controlled Trials (http://www.controlled-trials.com); Stroke Trials Registry (http://www.strokecenter.org/trials/); WHO International Clinical Trials Registry Platform (http://www.who.int/ictrp/en/);
- the following databases of conference abstracts: Conference Proceedings Citation Index Science (CPCI-S); China Medical Academic Conferences (CMAC 1995 to present) in CMCC (Chinese Medical Current Contents).
Searching other resources
In an effort to identify further published, unpublished and ongoing studies, we will:
- search reference lists of all relevant articles;
- contact study authors and researchers.
Data collection and analysis
Selection of studies
Two review authors (XC and HZ) will independently scan the title, abstracts and keywords of records obtained from the electronic searches and exclude obviously irrelevant studies. We will obtain the full-text articles of the remaining studies and the same two authors will independently select the studies for inclusion in the review based on the selection criteria outlined previously. We will resolve any disagreements through discussion and if necessary consult another review author for arbitration. If further information is required for a particular study, we will contact the study authors for clarification. We will add any study that requires further assessment to the 'Characteristics of studies awaiting classification' table.
Data extraction and management
Two review authors (XC and HZ) will independently extract data relating to patient characteristics, methods, interventions and outcomes, by using a data extraction form. We will resolve disagreements through discussion. For dichotomous outcomes we will extract the number of participants experiencing the event and the total number of participants in each arm of the trial. For continuous outcomes we will extract the mean value and standard deviation for the changes in each arm of the trial along with the total number in each group. Wherever possible, we will use outcomes from the intention-to-treat (ITT) population and, if not, then we will extract per protocol outcomes.
Assessment of risk of bias in included studies
We will assess the methodological quality of selected studies as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will score each of the following domains as 'yes', 'no' or 'unclear' (where 'yes' indicates that the study is less open to bias) and report them in 'Risk of bias' tables.
- Method of randomisation (selection bias).
- Concealment of allocation (selection bias).
- Blinding of investigators and patients (performance bias).
- Blinding of outcome assessment (detection bias).
- Incomplete outcome data (attrition bias).
- Selective reporting (reporting bias).
- Other possible bias. We will consider baseline comparability as one of the other sources of bias.
We will categorise each of these seven items as 'low risk ', 'high risk' or 'unclear risk' of bias. Where we classify a trial as 'unclear risk', we will contact the study authors for further information.
Two review authors (XC and HZ) will independently perform quality assessment. We will resolve any disagreements between authors arising at any stage through discussion or with a third author when necessary.
Measures of treatment effect
We will express results for dichotomous outcomes as risk differences (RD) with 95% confidence intervals (CI), and will express results for continuous outcomes as mean difference (MD) (if the same scale for each trial is available) or standardised mean difference (SMD) (if different scales were used). For continuous outcomes we intend to compare the change scores between groups after treatment and at the end of the follow-up period.
Unit of analysis issues
For studies with non-standard designs (e.g. cross-over trials, cluster-randomised trials) we will manage the data according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). For example, if we find any cross-over trials we will only analyse the first period.
Dealing with missing data
If data are missing, we will contact the original investigators for additional information. If some data remain unavailable, we will consider both best-case and worst-case scenarios.
Assessment of heterogeneity
We will assess heterogeneity among the results of trials with the Chi
Assessment of reporting biases
We will use the funnel plot method (Egger 1997).
We will use RevMan 5.2 (RevMan 2012) for all data entry and analysis. We will use a random-effects model to combine individual results. If there are no suitable studies, we will provide a narrative summary of study results.
Subgroup analysis and investigation of heterogeneity
If appropriate data are available, we intend to undertake subgroup analysis according to:
- stroke type: ischaemic stroke versus intracranial haemorrhage;
- duration of illness: intervention performed within the first three months versus after three months;
- type of vibratory stimulus: vertical platform versus oscillating platform.
We will perform sensitivity analyses as follows:
- excluding studies with inadequate concealment of allocation;
- excluding studies in which outcome evaluation was not blinded;
- excluding studies in which loss to follow-up was not reported or was greater than 10%;
- re-analysing the data by removing studies with assumed values to replace missing data.
We would like to thank Hazel Fraser, Managing Editor of Cochrane Stroke Group, Brenda Thomas, Trials Search Co-ordinator, attending staff of West China Hospital, and editors of the Cochrane Stroke Group for their valuable advice on writing this protocol.
Appendix 1. MEDLINE search strategy
- cerebrovascular disorders/ or exp basal ganglia cerebrovascular disease/ or exp brain ischemia/ or exp carotid artery diseases/ or exp intracranial arterial diseases/ or exp "intracranial embolism and thrombosis"/ or exp intracranial hemorrhages/ or stroke/ or exp brain infarction/ or vertebral artery dissection/
- (stroke or poststroke or post-stroke or cerebrovasc$ or brain vasc$ or cerebral vasc$ or cva$ or apoplex$ or SAH).tw.
- ((brain$ or cerebr$ or cerebell$ or intracran$ or intracerebral) adj5 (isch?emi$ or infarct$ or thrombo$ or emboli$ or occlus$)).tw.
- ((brain$ or cerebr$ or cerebell$ or intracerebral or intracranial or subarachnoid) adj5 (haemorrhage$ or hemorrhage$ or haematoma$ or hematoma$ or bleed$)).tw.
- hemiplegia/ or exp paresis/
- (hemipleg$ or hemipar$ or paresis or paretic).tw.
- exp Gait Disorders, Neurologic/
- (vibrat$ or WBV or SR-WBV or biomechanical stimulation$).tw.
- (oscillat$ adj5 (machine$ or platform$ or plate$)).tw.
- 9 or 10 or 11
- 8 and 12
- Randomized Controlled Trials as Topic/
- random allocation/
- Controlled Clinical Trials as Topic/
- control groups/
- clinical trials as topic/ or clinical trials, phase i as topic/ or clinical trials, phase ii as topic/ or clinical trials, phase iii as topic/ or clinical trials, phase iv as topic/
- double-blind method/
- single-blind method/
- placebo effect/
- cross-over studies/
- Therapies, Investigational/
- Research Design/
- evaluation studies as topic/
- randomized controlled trial.pt.
- controlled clinical trial.pt.
- (clinical trial or clinical trial phase i or clinical trial phase ii or clinical trial phase iii or clinical trial phase iv).pt.
- (evaluation studies or comparative study).pt.
- (random$ or RCT or RCTs).tw.
- (controlled adj5 (trial$ or stud$)).tw.
- (clinical$ adj5 trial$).tw.
- ((control or treatment or experiment$ or intervention) adj5 (group$ or subject$ or patient$)).tw.
- (quasi-random$ or quasi random$ or pseudo-random$ or pseudo random$).tw.
- ((multicenter or multicentre or therapeutic) adj5 (trial$ or stud$)).tw.
- ((control or experiment$ or conservative) adj5 (treatment or therapy or procedure or manage$)).tw.
- ((singl$ or doubl$ or tripl$ or trebl$) adj5 (blind$ or mask$)).tw.
- (coin adj5 (flip or flipped or toss$)).tw.
- (cross-over or cross over or crossover).tw.
- (placebo$ or sham).tw.
- (assign$ or allocate$).tw.
- 13 and 46
Contributions of authors
- Draft the protocol: Xueli Chang, Ming Liu, Sen Lin, Hongqing Zhou.
- Develop a search strategy: Xueli Chang, Ming Liu, Bo Wu, Sen Lin, Hongqing Zhou, Canfei Zhang.
- Search for trials: Xueli Chang, Hongqing Zhou.
- Obtain copies of relevant references: Xueli Chang, Hongqing Zhou.
- Trials selection: Xueli Chang, Ming Liu, Bo Wu, Hongqing Zhou.
- Data extraction and data entry: Xueli Chang, Hongqing Zhou.
- Analysis, write the final review and interpret the results: Xueli Chang, Ming Liu, Bo Wu, Sen Lin, Hongqing Zhou, Canfei Zhang.
- The review will be updated by Xueli Chang and Bo Wu.
Declarations of interest
Sources of support
- Chinese Cochrane Centre, Chinese Centre of Evidence-Based Medicine, West China Hospital, Sichuan University, China.
- No sources of support supplied