Pilates for low‐back pain
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To determine the effects of the Pilates method for patients with non‐specific acute, subacute and chronic low‐back pain.
Background
Non‐specific low‐back pain is a highly prevalent condition (Walker 2000) which is associated with disability and work absenteeism worldwide (Waddell 2004). Recent prognostic studies concluded that around 40% of patients with acute low‐back pain will not recover within three months (Henschke 2008; Costa 2012) and of these, only 40% will recover during the following 12 months (Costa 2009; Costa 2012). Not surprisingly, the costs associated with low‐back pain are enormous, causing a major economic burden for patients, government and health insurance companies (Dagenais 2008).
Exercise therapy is probably the most commonly used intervention for the treatment of patients with non‐specific low‐back pain. Exercise has a plausible biological rationale and low cost, and it has been recommended in most of the clinical practice guidelines for low‐back pain (Chou 2007; European Guidelines 2006), as well as by the most important systematic reviews on this topic (Hayden 2005; Hayden 2007). These reviews and guidelines have reported that regardless of the specific type of exercise, the outcome for patients is very similar. However, from the clinicians (and patients) point of view, it would be interesting to separate some forms of exercise in different reviews, as exercise programs vary largely in terms of intensity, number of treatment sessions, levels of individualisation and biological rationale. Therefore, well conducted systematic reviews on specific types of popular exercise programs are needed.
One type of exercise program that has been increasingly used for patients with low‐back pain over the last decade is the Pilates method (Musculino 2004; Queiroz 2005; Rydeard 2006). Pilates exercises were developed by Joseph Pilates in the 1920s and this method was originally named as “centrology” (Anderson 2000). These exercises can be performed with or without specialised equipment following six basic principles: centering, concentration, control, precision, flow and breathing (Wells 2012). The effectiveness of the Pilates approach has been tested in a few randomised controlled trials (Gladwell 2006; Rajpal 2008; Rydeard 2006; Curnow 2009; da Fonseca 2009). Our aim is to perform the first Cochrane systematic review on this topic in order to provide accurate and robust information on the effectiveness of the Pilates approach for low‐back pain, as compared to no intervention, placebo or other types of interventions.
Description of the condition
Low‐back pain is defined as pain and discomfort localised below the ribs and above the gluteal crease (where the upper leg meets the buttock), with or without referred leg pain (European Guidelines 2006). Non‐specific low‐back pain is the most common type, which can be defined as low‐back pain without any known specific cause or pathology such as nerve root compromise or serious spinal pathology (i.e. fracture, cancer and inflammatory diseases). Low‐back pain is often classified in three stages (acute, sub‐acute and chronic) according to its duration and this provides some information to the clinician with regards to treatment and prognosis. Acute low‐back pain is usually defined as an episode persisting for less than six weeks; sub‐acute low‐back pain as low‐back pain persisting between six and 12 weeks and chronic low‐back pain as low‐back pain persisting for 12 weeks or longer (European Guidelines 2006). For the purposes of this review, studies that recruited patients with non‐specific low‐back pain of any duration will be included, but analysed separately (if applicable).
Description of the intervention
The Pilates method was developed by Joseph Hubertus Pilates and consists of comprehensive body conditioning, which aims to develop better body awareness and improved posture (Queiroz 2005; Rydeard 2006). The exercises used by Pilates instructors mainly involve isometric contractions (i.e. contraction without joint movement) of the core muscles which make up the muscular centre responsible for the stabilisation of the body both while it is moving or at rest. Pilates became popular as a treatment for low‐back pain long after Joseph Pilates died. Traditional Pilates exercises follow six basic principles: centering (i.e. tightening the powerhouse (trunk muscles)), concentration (i.e. cognitive attention while performing the exercises), control (i.e. postural management while performing the exercises), precision (i.e. accuracy of exercise technique), flow (i.e. smooth transition of movements within the exercise sequence) and breathing (Wells 2012) in coordination with the exercises. A recent systematic review of Pilates exercises concluded that another principle should be added whenever these exercises are used in the treatment of low‐back pain, which is posture (Wells 2012). Pilates exercises are usually prescribed by certified instructors. The exercises are considered to be similar to spinal stabilisation exercises (also known as motor control exercises); however, they do not involve conscious activation of specific muscles in the manner often used in spinal stabilisation exercises. During dynamic exercises co‐contraction of the multifidus (a deep back muscle), transversus abdominis (a deep abdominal muscle), pelvic floor and diaphragm muscles is observed. The goal of the co‐contraction of these muscles is to reduce joint compression and alter pelvic tilt (Bryan 2003; Gladwell 2006).
The Pilates method includes several stretching and strengthening exercises, which can be divided into two categories: mat Pilates (exercises performed on the ground, without any specific equipment) and exercises with the Pilates apparatus. The first exercises developed by Pilates were performed on the ground; he then created a series of apparatus on which to perform exercises against resistance provided by springs and pulleys (Musculino 2004; Queiroz 2005). The reported benefits of Pilates exercises include improvements in strength, range of motion, coordination, balance, muscle symmetry, flexibility, proprioception (awareness of posture), body definition and general health (Bryan 2003; Gladwell 2006). The exercises are adapted to the condition of the patient, and difficulty is gradually increased while respecting individual abilities and characteristics. The springs and pulleys of each apparatus can be used to make the exercises easier or more difficult to perform.
How the intervention might work
The biological rationale for how Pilates exercises might work is based upon the idea that stability and control of spinal muscles are altered in people with low‐back pain (Hodges 1996). Two motor control impairments are proposed to occur in people with low‐back pain: first the onset of activity of deep muscles such as the multifidus and transversus abdominis is delayed when the stability of the spine is challenged in dynamic tasks (Rackwitz 2006). Second, patients with low‐back pain tend to compensate for this lack of stability by increasing the activity of superficial muscles (Hodges 1996; Rackwitz 2006) which increases the stiffness of the spine. The exercises advocated by the Pilates approach aim to target these two factors (i.e. improving the stability of the spine by improving the motor control of the deep muscles and to reduce the activity of superficial muscles) as well as improve posture and body awareness. These factors have the potential to improve pain, disability and quality of life of patients with low‐back pain.
Why it is important to do this review
Over the last decade, the popularity of the Pilates method as an intervention for patients with low‐back pain and other musculoskeletal conditions has steadily increased worldwide. There are published trials (Gladwell 2006; Rajpal 2008; Rydeard 2006; Curnow 2009; da Fonseca 2009) and systematic reviews (Lim 2011; Posadzki 2011; Pereira 2012) available on this topic. However, we are aware of new existing trials on this topic. Therefore, a well conducted systematic review is needed to better inform clinicians, patients and policy makers about the effectiveness of this intervention in patients with non‐specific low‐back pain.
Objectives
To determine the effects of the Pilates method for patients with non‐specific acute, subacute and chronic low‐back pain.
Methods
Criteria for considering studies for this review
Types of studies
Only randomised controlled trials will be included; trials that used quasi‐random procedures will not be considered for this review.
Types of participants
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Inclusion criteria
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Adult participants aged 16 or older with acute, subacute or chronic non‐specific low‐back pain
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Patients recruited from primary, secondary or tertiary care; these patients could be either seeking care for back pain or recruited from the community
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Exclusion criteria
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Patients with any contraindication to exercise therapy
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Pregnancy
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Patients with serious spinal pathology (i.e. cancer, fracture, cauda equina syndrome and inflammatory diseases)
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Trials that included more than 5% of participants with evidence of nerve root compromise
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Types of interventions
We will consider any type of exercise therapy that followed the Pilates method. Trials will be judged to have evaluated Pilates when the following criteria are met:
1. The study explicitly states that the intervention was based upon the Pilates principles (i.e. centering, concentration, control, precision, flow, breathing and posture) or at least three of these elements (Wells 2012).
2. The therapists who provided the interventions have previous training in Pilates exercises or the therapists were described as certified Pilates instructors.
We will perform a sensitivity analysis by excluding trials where the definition of the intervention is not as clear as stated above.
Types of outcome measures
We will include any type of clinically relevant measure that could be considered patient‐centred. Physiological and biomechanical variables (for example, range of motion, motor control, muscle endurance) will not be considered for this review.
Primary outcomes
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Pain intensity measured by any reliable and valid self report outcome measure.
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Disability measured by any reliable and valid self report outcome measure.
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Global impression of recovery measured by any reliable and valid type of Global Perceived Effect Scale.
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Quality of life (measured by any reliable and valid instrument).
Secondary outcomes
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Return to work (measured by any reliable and valid instrument).
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Adverse effects.
Search methods for identification of studies
Electronic searches
We will search for randomised controlled trials from the following electronic databases without restrictions of language or date of publication. We will use the search strategies developed by the Cochrane Back Pain Review Group. All databases will be searched from the date of their inception to January 2013.
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MEDLINE (Appendix 1)
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EMBASE (Appendix 2)
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CINAHL (Appendix 3)
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CENTRAL (Appendix 4)
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PEDro (Appendix 5)
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SPORTDiscus (Appendix 6)
Searching other resources
We will also search reference lists of eligible papers as well as trial registry websites (Australian and New Zealand Clinical Trials Registry, National Research Registry, Clinical Trials.org, meta‐register of Controlled Trials, Brazilian Registry of Clinical Trials, etc).
Data collection and analysis
Selection of studies
Two review authors (CMNC and LCMC) will independently screen titles and abstracts for potentially eligible studies. Full text papers will be used to determine the final inclusion in the review. Disagreements between review authors will be resolved through discussion or by arbitration of a third reviewer (LOPC) when consensus cannot be reached. We will include only full text papers, written in any language, regardless of the date of publication. Papers written in English, Portuguese, Spanish, Italian and Dutch will be included as the review team includes authors able to read these languages. All remaining papers that are written in languages other than these will be sent to translators. We will also scan reference lists from previous published reviews on Pilates as well as scan reference lists from the eligible randomised trials.
Data extraction and management
We will extract relevant data from each of the eligible papers by using a standardised data extraction form that will contain:
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bibliometric data (authors, year of publication, language);
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study characteristics (study design, sample size, description of the sample, country, recruitment modality, funding);
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characteristics of the participants (gender, age, duration of symptoms, severity of the condition at baseline);
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description of the interventions (both experimental and control interventions), including dose (number of sessions, duration of each session of treatment, etc) and co‐interventions;
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duration of follow‐up assessments;
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outcomes assessed;
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study results;
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time periods for outcome assessment: short (less than three months after randomisation), intermediate (at least three months but less than 12 months after randomisation) and long term (12 months or more after randomisation) follow‐ups. When there are multiple time points that fall within the same category the one that is closer to the end of the treatment, six months and 12 months will be used.
Assessment of risk of bias in included studies
The assessment of risk of bias in included studies will be performed by using the risk of bias assessment tool as recommended by The Cochrane Collaboration (Higgins 2011) and the Cochrane Back Review Group (Furlan 2009) (Appendix 8).
This risk of bias assessment will be performed independently by two review authors (CMNC and LCMC) and possible disagreements between reviewers will be resolved by discussion, or arbitration by a third reviewer (LOPC) when consensus cannot be reached. Each of the 12 items of the risk of bias assessment will be scored as "high", "low" or "unclear". A study with a low risk of bias is to be defined as having low risk of bias on six or more of these items, and subgroup analyses will be performed based upon this assessment (i.e. we will perform subgroup analyses considering studies judged to have a high or low risk of bias). Data extraction will be pilot tested by using two RCTs on back pain.
We will assess clinical relevance (Appendix 9) by scoring five questions related to this domain as "yes", "no" or "unclear". This will be done by two independent review authors and possible disagreements will be resolved by discussion, or arbitration by a third reviewer when consensus cannot be reached.
Measures of treatment effect
We expect to deal mostly with continuous outcome measures to determine the treatment effect, such as mean differences for pain, disability or quality of life. As these outcomes can be measured with different scales we anticipate quantifying effects with the standardised mean difference (SMD); however, if the same scale is used we will use the weighted mean difference (WMD). We also expect to encounter dichotomous outcomes such as recovery or return to work and in such cases we will calculate relative risks (RR) of experiencing the positive outcome. Funnel plots will be used to evaluate reporting bias (i.e. a funnel plot showing evidence of small study effects) if we retrieve a minimum of 10 trials. Effect sizes and 95% confidence intervals (CI) will be used as a measure of treatment effect. Differences of at least 20% will be considered as clinically important (Ostelo 2008). We will use Review Manager 5for all analyses.
Unit of analysis issues
We are not expecting unit of analysis issues with regards to cross‐over or cluster randomised trials as these types of trials are not expected to occur in exercise trials. However, we do expect to find repeated observations on participants in most of the eligible trials. In this case we will follow the advocated strategy of defining the outcomes (already stated above) as well as the time points a priori (Higgins 2011). The time points are short (less than three months after randomisation), intermediate (at least three months but less than 12 months after randomisation) and long term (12 months or more after randomisation) follow‐ups. When there are multiple time points that fall within the same category the one that is closer to the end of the treatment, six months and 12 months will be used. If studies include multiple treatment arms and, therefore, multiple comparisons we will firstly aim to select the most appropriate comparison. If two groups are considered to be the same (e.g. 2 controls: waiting list and no treatment) the ‘shared’ intervention will be split in order to be able to include two (reasonably independent) comparisons.
Dealing with missing data
Firstly, review authors will contact the authors by email of each study requesting any necessary data that might not be properly reported in the manuscript. In cases where data are reported as a median and interquartile range (IQR), it will be assumed that the median is equivalent to the mean and the width of the IQR is equivalent to 1.35 times the standard deviation (Higgins 2011). Data can be also estimated from graphs in the case that this information would not be presented in tables or text. If any information regarding standard deviations is missing, we will calculate them from confidence intervals (if available) of the same study. Finally, if no measure of variability is presented anywhere in the text, we will estimate the standard deviation from similar patient groups, taking the risk of bias of individual studies into consideration.
Assessment of heterogeneity
The assessment of heterogeneity will be based upon visual inspections of the forest plot (e.g. overlapping confidence intervals) and more formally on the Chi2 test and the I2 statistic recommended by the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Results will be combined in a meta‐analysis using a random‐effects model if I2 < 50%. If substantial heterogeneity is present, we will not combine the results but instead present them as a narrative synthesis.
Assessment of reporting biases
We will try to perform comprehensive searches in order to reduce the possibility of reporting biases and we will also generate funnel plots (if we retrieve at least 10 trials) in order to determine possible reporting biases, i.e. small study effects (Higgins 2011).
Data synthesis
The results from individual trials will be combined if possible through a meta‐analysis. This pooling of the data (if applicable) will be dependent on the level of heterogeneity of the retrieved studies. Results will be combined in a meta‐analysis using a random‐effects model if I2 < 50%. If substantial heterogeneity is present, the results will not be combined but presented as a narrative synthesis.
Regardless of whether there are sufficient data available to use quantitative analyses to summarise the data, we will assess the overall quality of the evidence for each outcome. To accomplish this, we will use the GRADE approach, as recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) and adapted in the updated Cochrane Back Review Group method guidelines (Furlan 2009). Factors that may decrease the quality of the evidence are: study design and risk of bias, inconsistency of results, indirectness (not generalisable), imprecision (sparse data) and other factors (e.g. reporting bias). The quality of the evidence for a specific outcome will be reduced by a level, according to the performance of the studies against these five factors.
High quality evidence: there are consistent findings among at least 75% of RCTs with low risk of bias, consistent, direct and precise data and no known or suspected publication biases. Further research is unlikely to change either the estimate or our confidence in the results.
Moderate quality evidence: one of the domains is not met. Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality evidence: two of the domains are not met. Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality evidence: three of the domains are not met. We are very uncertain about the results.
No evidence: no RCTs were identified that addressed this outcome.
Subgroup analysis and investigation of heterogeneity
We will stratify some of the analysis based upon a number of factors if needed (Higgins 2011):
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duration of symptoms (i.e. acute, subacute and chronic low‐back pain);
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types of control groups (e.g. minimal intervention, placebo, another type of treatment, wait‐and‐see groups);
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duration of follow‐ups (i.e. short, medium and long term);
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risk of bias (i.e. low and high risk of bias studies).
Sensitivity analysis
We are not planning to perform any sensitivity analyses as the number of studies and comparisons is expected to be low.
