The Importance of Pragmatic over Explanatory Randomised Controlled Trial in Musculoskeletal Physiotherapy Practice

Depending on the choice of research methodology, there are several research designs such as a single observational case study, a cohort or case-controlled design, non randomised and randomised controlled trials (RCTs). While RCTs are widely considered as the gold standard for assessing the effectiveness of different physiotherapy interventions, there are two types of RCT mainly explanatory and pragmatic RCT. It is the opinion of the author that a pragmatic RCT approach that not only have realistic treatment sessions but also involve less costs and personnel are best suited for musculoskeletal studies undertaken in a normal clinical environment to enhance their generalisation.


Introduction
Research evidence suggests the number of physiotherapy treatment sessions varies over treatment episodes [1], however,  Table 1 below). sample size and funding [6]. Although case studies are likely to demonstrate clinically significant improvement in outcomes of pain and function, it must not be forgotten that they cannot rule out the effects of natural resolution, bias and other confounders such as the real cause of the improvement [7]. However, single case studies should provide some motivation for conducting the appropriate and necessary trials such as non RCTs and RCTs [8].
Non RCTs can detect associations between an intervention and an outcome, however they cannot rule out the possibility that the association was caused by a third factor linked to both intervention and outcome [9]. RCTs are widely considered as the gold standard for assessing the effectiveness of different interventions such as shoulder injections, because they allow us to be confident that a difference in outcome can be directly attributed to a difference in the treatments, rather than some other confounding variables (age and gender) [10,11]. However, other factors, such as patient's clinical experience of the intervention, as well as the quality and quantity of treatment received have been suggested to play a role in determining treatment outcomes [12]. Therefore, an RCT that combines these aspects by investigating the effectiveness of the free of bias but lacking in its application beyond the immediate clinical environment in which it was conducted [12]. This view was strongly re-echoed Rothwell [15] which it stated: "Lack of consideration of external validity is the most frequent criticism by clinicians of RCTs, systematic reviews, and clinical guidelines" [15].
To resolve this Treweek & Zwarenstein [13] has suggested the use of well-designed trials that adopt a pragmatic approach. Therefore, it is my opinion that for a pragmatic RCT approach to be adopted as a research design, it should have realistic treatment occasions and transferable to normal clinical environment where most people with musculoskeletal conditions are easily diagnosed and treated [16] to enhance its generalisation.

Pragmatic Versus Explanatory Randomised Controlled Trial
Schwartz & Lellouch [17] describe two different types of RCT, explanatory and pragmatic. They proposed a distinction between explanatory and pragmatic trials. It is their view that many trials (such as explanatory trials) were limited in their applicability beyond the artificial, laboratory environment. Explanatory trials are aimed at validating a physiological hypothesis by specifically proving a causal relationship between administration of a treatment (a drug) and a physiological outcome (such as inflammation) [17]. Although however, they are not applicable in normal physiotherapy practice that lack such highly controlled environments. Pragmatic trials have been offered as a solution in that they retain the rigour of randomisation but are still applicable to normal clinical practice [18]. It is for these reasons that musculoskeletal studies should adopt a pragmatic approach which takes into account realistic treatment occasions which occurs in a normal clinical so that findings from such trials can be easily transferable to practice.
For example Eadie et al [19], in a pragmatic RCT that investigated exercise versus group biomechanical exercise in chronic low back patients using a one-hour session per week, which is what obtains in every day practice. The implication of this of this study's findings is that it has realistic treatment occasion that is easily transferable to practice. The differences between the two approaches are also highlighted in the use of efficacy and effectiveness [20]. Explanatory trials deal with efficacy as these studies assess differences in effect between two or more conditions under ideal, highly controlled conditions. Although the tight controls of explanatory trials result in maximal internal validity, external validity could be lost [33]' because replicating them under normal clinical practice is difficult. Explanatory trials are thought to be well suited to medical drug trials, which are usually double or triple blinded, and involve the use of a placebo control group [33]. Pragmatic RCTs utilise effectiveness, which assesses differences in effect between two or more conditions in normal clinical circumstances, thus retaining internal validity and enhancing external validity [33].
It is the opinion of [33]. that pragmatic RCTs are generally more suited to assessing musculoskeletal interventions such as exercise prescription for managing low back or shoulder pain. Explanatory trials are usually more expensive, take more time and involve more personnel, unlike pragmatic trials. These difficulties are the reasons why a pragmatic approach is best suited for musculoskeletal research within the community. The benefits are that less extra costs or personnel that would be involved in such studies because they are more likely to take place within normal clinical hours with the usual staff involved.

Pragmatic Randomised Controlled Trial-Why it is Important
In a normal community practice where most people with musculoskeletal pain are diagnosed and managed [16], a pragmatic RCT design is important if they have realistic treatment, occasions, which can be transferred to practice. A pragmatic RCT is aimed at determining the effectiveness of two or more interventions under the usual conditions or real-life settings in which they are applied [21]. Pragmatic trials including RCT are aimed at ensuring that the care delivered in the setting in which trials are conducted matches the care delivered in the setting to which its results are applied [3]. Pragmatic RCTs are generally linked with clinical practice and they incorporate clinical outcomes that are relevant to inform decision makers such as patients, clinicians, health commissioners and policy makers about interventions that are applicable to a wide range of clinical settings [21]. These trials adopt minimal exclusion criteria in order for the patients to reflect those receiving care within the normal population [21]. This is so that treatment

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the current economic climate and given the pressure to improve healthcare delivery within the community, pragmatic RCTs have received widespread support and acceptance from clinicians, researchers and policy makers [22]. Healthcare commissioners and policy makers are very interested in pragmatic trials because they are designed to answer important and relevant questions, which are centred on comparative effectiveness of interventions in the normal clinical practice [23]. However, those trials should not only have realistic treatment sessions but also involve less costs and personnel. Since the local Clinical Commissioning who commissions musculoskeletal practice are interested in knowing the clinical outcomes, involving them and GPs during the planning stages of musculoskeletal research is very important. This is consistent with the suggestion by [22] that decision makers such as healthcare providers and policy makers should be included in the design of pragmatic trials.

Eligibility
To what extent are the participants in the trial similar to those who would receive this intervention if it was part of usual care?
The study participants were patients that have been referred to the service by their general practitioner with shoulder pain who usually could be treated with standard care or intervention using treatment approach.

Recruitment
How much extra effort is made to recruit participants over and above what would be used in the usual care setting to engage with patients?
The service where thus study took place receives referrals from 33 GP practices in the area. Therefore, prior to the study, presentations were made to the general practitioner's in the area via the clinical commissioning group (CCG) and to the Extended Scope Practitioners and the Physiotherapists at the researcher's place of work to inform them of the study and enhance recruitment of participants.

Setting
How different are the settings of the trial from the usual care setting?
All the participants recruited to the study were from a population of patients attending a community Musculoskeletal service.

Organisation
How different are the resources, provider expertise, and the organisation of care delivery in the intervention arm of the trial from those available in usual care?
No extra cost or personnel was involved in this study. The clinicians involved in this study and the treatment they provided were similar to the care they would normally provide in their clinical practice.

Flexibility in delivery
How different is the flexibility in how the intervention is delivered and the flexibility anticipated in usual care?
The flexibility applied to the intervention in this study was similar to the usual care.

Flexibility in adherence
How different is the flexibility in how participants are monitored and encouraged to adhere to the intervention from the flexibility anticipated in usual care?
In this study standard after care and post-injection information were provided verbally and in the form of information leaflet based usual care.

Follow-up
How different is the intensity of measurement and follow-up of participants in the trial from the typical follow-up in usual care?
Participants in the study were assessed three times during the study period, at 0 (baseline), 8 and 12 weeks. The 0 and 8 weeks' timeframe is common in normal clinical practice and previous authors (Akgun et al 2004) have used the 12 weeks' follow-up period. At follow-up, the outcomes of the injection were evaluated via a telephone call similar to normal clinical practice.

Primary outcome
To what extent is the trial's primary outcome directly relevant to participants?
The primary outcome -shoulder pain disability index and numeric pain rating scale that were used used in normal clinical practice.

Primary analysis
To what extent are all data included in the analysis of the primary outcome?
In this study, all data were included in the analysis of the primary outcome. Once a participant is randomised to an arm of treatment, they should be analysed in the group to which they were allocated to after randomisation.

Conclusion
While RCTs are widely considered as the gold standard for assessing the effectiveness of different interventions such as shoulder injections, there are basically two types of RCT mainly explanatory and pragmatic RCT. Although each design has its own strengths and weaknesses, the choice of methodology may be influenced by factors such as the research question, ethical issues and clinical practice environment [6]. It is the opinion of the author that a pragmatic RCT approach that not only have realistic treatment sessions but also involve less costs and personnel are best suited for musculoskeletal studies undertaken in a normal clinical environment to enhance their generalisation.