Pain can be defined as 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage' and is considered chronic when it 'persists beyond the normal time of healing' (Merskey and Bogduk, 1995). A recent survey studying 4,839 people found 20% suffered from chronic pain with many reporting a reduction in quality of life (Breivik et al, 2006).
Treatment of chronic pain is evolving. In the last three decades there have been many critics of western biomedicine's poor integration of social and psychological factors in the assessment/treatment of pain. Such critiques commonly reject the Cartesian mind-body dualism model of pain (which is popularly traced to Descartes) where the body is seen as separate from the mind. The Cartesian model is an early biomedical model which relates the intensity of pain to the severity of injury. In contrast, the biopsychosocial model, first proposed by Engel in 1977, views illness as a 'dynamic and reciprocal interaction between biologic, psychological and sociocultural variables that shape the person's responses to pain' (Turk and Flor, 1999). A current example of a biopsychosocial model is the World Health Organisation's International Classification of Functioning model which shifts focus from cause of illness to the impact it has on the individual. Similarly, the Chartered Society of Physiotherapy defines physiotherapy as 'a physical approach to promote, maintain and restore physical, psychological and social well-being'.
It is vital for student physiotherapists to understand what the biopsychosocial model of pain has to offer physiotherapy practice as they will be fundamental in facilitating future change within the physiotherapy field. The biopsychosocial model, what it has to offer and the implications of putting it into practice will now be explored in turn.
Biopsychosocial versus the biomedical model in clinical practice
The biomedical model embraces reductionism and assumes disease is caused by any deviation from the norm of measurable biological/somatic variables and believes the only effective treatment for pain is via medical approaches. It is relevant for many disease-based illnesses and is supported by a wealth of biological findings. The model is effective in acute illnesses that have predictable outcomes (e.g. treatment for bacterial infections using antibiotics) and is therefore suitable to healthcare practitioners (HCP's) who have to focus on one part of an individual's health. However, despite success in the treatment of many disease processes, some difficult and important medical problems have proven resistant to the biomedical model. For example, the biomedical model does not explain why pain can continue when tissue damage is no longer present (chronic pain) or clinical phenomena such as phantom pain. It leaves no room within its framework for the social, psychological, and behavioural dimensions of illness (Engel, 1977).It was for reasons such as these that Engel felt it necessary to widen the approach to disease to include the psychosocial without sacrificing the huge advantages of the biomedical approach.
Engel argued that the biopsychosocial model can be used to obtain a better understanding of the disease process. The biomedical model looks at the underlying pathophysiology in isolation and often cannot explain why prescribed treatments fail, e.g. treatment for chronic low back pain (LBP). The biopsychosocial model however extends beyond medical-care and looks at the patient's unique biologic, psychological, social, co-morbidities, illness beliefs, coping strategies, fear, depression, employment, and financial concerns and may give further insight into what has hindered recovery and sustained patient-hood. Waddell (2006) even concludes that 'spinal pain/disability can only be understood and managed according to a biopsychosocial model'. The biopsychosocial model gives the clinician biologic and psychosocial factors with which to explain why people persist with pain and therefore a set of alternative tools to treat patients.
Additionally, the biopsychosocial model understands that pain can be a dynamic entity that changes over time and is affected by a person's internal and external environment. For example, a physical injury may cause pain initially, over time this is exacerbated by fear-avoidance (a psychological variable) and work-related stress (social variable) leading to physical deconditioning, creating a self-perpetuating cycle (e.g. Al-Obaidi et al.,2000, Goubert et al.,2005). The cause and effect are difficult to disentangle and suggests successful treatment would require a holistic approach.
The biopsychosocial model uses a holistic approach as it aims to treat both the patient and the disease. For example, using the biomedical model(which focuses solely on the disease/impairment) treatment for a sprained ankle is independent of the patient; treatment includes rest, compression, and elevation. Using the biopsychosocial model, treatment would be based on the individual. For example, if the patient was a busy mother, treatment would be adjusted accordingly by understanding that rest may not be achievable for this individual due to social factors. There is however those that believe the biopsychosocial model is flawed and their views must be considered when assessing what contribution the biopsychosocial model makes to physiotherapy practice.
Critics argue that the biopsychosocial model has weaknesses, for example, over reliance on subjective outcome measures (Weiner, 2008). Subjective outcome measures such as the SF-36, Pain Disability Questionnaire and VAS have gained "validity" and widespread use. Some argue there is little regard for the traditional biomedical objective outcome measures that assess pathoanatomic/pathophysiologic outcomes(Weiner, 2008). However, many outcomes in chronic pain, such as stress and pain itself are subjective and cannot be measured objectively. Furthermore, using objective outcome measures does not guarantee validity, for example, some rely on sophisticated performance-based equipment which requires the subject to perform at a maximal level for optimal validity. Functional performance will be influenced by motivation, fear, understanding of instructions and physical ability (Gatchel and Turk, 2008) therefore the measure will still have some degree of subjectivity. Critics also argue the biopsychosocial approach has led to a loss of attention to pathophysiology or under diagnosis of, for example, musculoskeletal disorders in chronic LBP (Weiner, 2008) and allows medically unexplained pain to be shifted too readily to the domain of psychiatry (Duncan, 2000). Those in favour of the biopsychosocial model argue that the biomedical model is incomplete, rather than incorrect (Gatchel and Turk, 2008).
Reviews of the literature do however generally support the effectiveness of a biopsychosocial approach (Ostelo et al.,2005,George,2008, Scascighini et al.,2008) and frequently find multi-disciplinary, multi-modal treatments give good outcomes in the treatment of chronic pain. Others argue that multidisciplinary biopsychosocial rehabilitation requires substantial staff and financial resources. Similarly Karjalainen(2003) found there was not enough good evidence to support multidisciplinary rehabilitation in adults with neck/shoulder pain. However this study was a methodologically low quality randomised controlled trial(RCT) which failed to randomize patients, use a power calculation or intention-to-treat analysis. In contrast, high quality studies (Mosely et al.,2002,Smeets, 2006) looked at biopsychosocial approaches to individual physiotherapy care (which requires less financial resources) and provided strong evidence of their effectiveness. They had a population match to the target population (primary care) and were sufficiently well described to be applied by a sole physiotherapy practitioner. It is interesting to note that such studies are in the form of biomedically orientated RCT's whereas it is qualitative research that is concerned with exploring people's perceptions, beliefs, attitudes and experiences.
However, evidence suggests that the transition from the biomedical to the biopsychosocial model is incomplete (Bishop et al.,2008) and that its incorporation into medical practice is taking longer to transpire than predicted (Alonso, 2003). Furthermore, Cote(2009) questioned the tenability of the biomedical model but found it is still frequently used by physiotherapists.
Biopsychosocial model and the physiotherapist
Integration of emerging evidence from the pain sciences (advocating biopsychosocial approaches) into the clinical reasoning process is an example of movement within the physiotherapy profession towards a more evidence based approach to clinical practice. It would therefore be expected that physiotherapists would have adjusted their practice accordingly; however evidence suggests HCP's are continuing to treat chronic pain via biomedical approaches (Bishop and Foster, 2005,Cote, 2009) and failing to use collaborative goal-setting and patient-centred care (Edwards et al, 2004).
Practical application of the biopsychosocial model to physiotherapy has been challenging in that it forces clinicians to expand the scope of factors assessed as part of comprehensive patient management. Many physiotherapists do not feel confident or competent enough to address psychological factors as they are perceived as being more difficult to treat (Daykin and Richardson, 2004, Cote,2009). The question of whether or not physiotherapists are within the limits of professional practice to treat psychological factors should also be considered at this point. Previously, physiotherapist training was based on the biomedical model and failed to teach skills necessary for psychosocial assessment. As a consequence, physiotherapists currently working in clinical practice are not satisfied with the education they have received (Parsons et al.2007). This is supported by Moseley (2003) who found physiotherapists to have poor knowledge of the neurophysiology of pain. Consequentially, physiotherapist attitudes and beliefs about chronic pain have been shown to affect the advice/treatment they provide to patients (Daykin and Richardson, 2004, Bishop,2007).
Daykin and Richardson (2004) found physiotherapists who felt ill-equipped addressing psychosocial aspects had a tendency to attribute patient pain to structural causes and this was reflected in the treatment they provided. Whilst the physiotherapists believed in a mutually collaborative model, they were more comfortable using the therapist centred biomedical model. Similarly, Linton (2002) found that one-third of physiotherapists studied believed a reduction in pain is a prerequisite for return-to-work, two-thirds would advise patients to avoid painful movements, and 25% believed sick-leave is a good treatment for LBP, all of which are contradictory to current guidelines and reflective of biomedically orientated treatment. Furthermore, such advice and treatment could actually exacerbate chronicity in the presence of psychosocial factors (Pincus et al.,2002). The study concludes that some practitioners hold beliefs reflecting fear-avoidance and these beliefs influence treatment. These studies provide valuable insight into the difficulties of implementing research findings into practice. It is however vital practicing physiotherapists are capable of ongoing self-audit in order to develop their professional skills and follow the advances of the medical profession and health sciences.
This lack of formal teaching and the influence of experienced physiotherapists (accustomed to biomedical methods) on newly qualified physiotherapists may help explain why the biopsychosocial model is taking longer to transpire than predicted (Casserley-Feeney et al.,2008). However, with increased emphasis on biopsychosocial approaches in undergraduate syllabuses it is likely to become ingrained into clinical practice. It is however not only the attitudes and beliefs of the physiotherapist that must be challenged, indeed the attitudes and beliefs of the patient are crucial in ensuring the efficacy of biopsychosocial approach.
Biopsychosocial model and the patient
The biomedical model considers the patient to be a passive recipient of treatment and a victim of circumstance with no accountability for their disease. It takes responsibility for illness away from the patient which may cause a threat to patient autonomy. The biomedical approach is clinician orientated and requires the patient to submit to the clinical "expert" who dominates the relationship. Additionally, the use of the term "patient" reinforces the biomedical model and encourages passivity of the patient. Some physiotherapists may wish to preserve this inequality to maintain control of rehabilitation/treatment. In contrast the biopsychosocial model aims to encourage patients to contribute to their treatment (e.g. through shared decision-making) and empower them in self-managing their pain (Edwards et al.,2004). However, if patients believe their pain is solely physiological they are less likely to accept self-management(Underwood,2006) or biopsychosocial approaches (Stone, 2002). It is therefore vital to establish patient pain beliefs in order to provide an effective intervention.
Urquhart et al. (2008) supports the need to alter maladaptive beliefs/behaviours. The study suggests negative beliefs (e.g.fear-avoidance)are predictive of chronic, disabling pain and that changing these beliefs is more important than biomedical factors in pain intervention success, supporting the need for a biopsychosocial model. Cognitive-behavioural approaches aim to alter such beliefs/behaviours through methods such as graded exposure. Reviews of the literature (e.g Turk, 2008, Lunde etal.,2009)commonly find CBT to be an effective treatment for chronic pain, although they highlight methodological weaknesses, in particular that many trials are statistically underpowered. The efficacy of these interventions provides further support to the theory that pain is not a purely physical experience.
Just as the biomedical model allowed significant medical advances, the biopsychosocial model has offered physiotherapy a wider spectrum of tools to help treat chronic pain patients. Transition from the biomedical model to the biopsychosocial model is by no means complete. Many physiotherapists still use predominantly manual techniques despite the presence of psychosocial factors which helps reinforce the biomedical view of pain still held by many patients. The challenge is therefore changing beliefs of both HCP's and patients. Increased patient education and therapist support is needed to facilitate the recommended changes into practice, as evidence based approaches to healthcare demands physiotherapists utilize practices that are clearly shown to be effective.