The biopsychosocial model of pain in physiotherapy: past, present and future

Abstract

Background

The biopsychosocial model of pain may aid the understanding pain and its clinical presentations.

Objectives

This paper presents a discussion of the past, present and future state of the biopsychosocial model of pain within physiotherapy.

Main Findings

The biopsychosocial model of pain acknowledges the dynamic interdependent biological, psychological and social dimensions of peoples pain experiences and has been widely endorsed. However, the biopsychosocial model is not beyond criticism and its applicability to clinical practice has been questioned. Researchers have investigated how clinicians understand and apply the biopsychosocial model in clinical practice. Evidence suggests that physiotherapists demonstrate varying levels of confidence and proficiency in their psychosocially-oriented clinical knowledge and practice. Psychologically informed physiotherapy treatment approaches have been described and trialled and show inconsistent results and effect sizes with respect to patient-related outcomes. In addition, commentators suggest that the ‘-social’ dimension of the model has been relatively neglected. While there is some evidence that the biopsychosocial model is evolving, and efforts are underway to develop and validate clinically-applicable tools, physiotherapy clinicians, educators and researchers have been invited to consider existing barriers and enablers to the implementation of the biopsychosocial model in clinical practice in order to improve its understanding and application within healthcare.

Conclusion

The biopsychosocial model invites clinicians to understand and address the biological, psychological, and social dimensions of patients pain. Understanding and implementation of the biopsychosocial model of pain in physiotherapy is mixed. Improving education and training and developing and evaluating innovative biopsychosocial-oriented interventions appear to be important ways forward. The biopsychosocial model of pain is evolving in response to scientific and clinical developments.

KEYWORDS:

• Biopsychosocial
• pain
• physiotherapy

Introduction

Understanding pain and its clinical presentations is vital given its prevalence and adverse personal and socioeconomic impact. Approximately 20-30% of the adult populations of Europe and United States of America are affected by chronic (typically ≥ 3 months in duration) pain [1–4]. According to the Global Burden of Disease Study 2016, pain and pain-related diseases (e.g. low back and neck pain) are leading causes of disability and disease burden globally [5]. Chronic pain can have a profound adverse impact on the daily activities, quality of life and mental health of those who suffer with it, together with wider consequences on home, work and social life [6,7]. The economic costs arising from healthcare expenditure, lost work productivity, absenteeism and early retirement secondary to chronic pain can be enormous to nations, running into billions annually [1].

The biopsychosocial model of pain is one of a number of pain-related models relevant to physiotherapy that provides a framework designed to inform our understanding, assessment and management of clinical presentations of pain. This objective of this opinion piece is to present a discussion of the past, present and future state of the biopsychosocial model of pain within physiotherapy.

The puzzle of pain

Clinically, two explanatory models of pain have had particular prominence in shaping the understanding and treatment of clinical presentations of pain within physiotherapy and medicine generally; these are the biomedical and biopsychosocial models [8].

It has been suggested that within physiotherapy clinical interpretations of pain remain largely grounded within the biomedical model of illness [9]. The biomedical model is considered ‘reductionist’ in that it functions on the premise that all pain has a dominant anatomical or pathological source in which pain is considered to be a simple signal of tissue injury or pathology, transmitted along a relatively hard-wired neurobiological connection between the anatomical site of injury/pathology and the brain [10].

The biomedical model, it has been suggested, may be useful and necessary for the identification of specific mechanical problems or when disease or injury is present in tissues, particularly in instances of acute injury [11]. However, interpretations of pain based on the biomedical model and its structure/pathology-oriented approach have been criticised since such approaches do not explain either the complexity or variability inherent within many clinical presentations of pain where; i) pain is reported in the absence of any clearly identifiable pathology, ii) pain is reported to persist after healing, iii) pain is absent despite evidence of injury or pathology, iv) the severity of pain is at odds with the severity of injury or pathology, v) patients’ reports of pain severity in response to similar severities of injuries differs greatly, vi) relationships between pain, impairment and disability are unpredictable and incongruous and vii) where patients’ responses to identical interventions for the same injury or pathology are highly variable [10,12–14], since by the tenets of the biomedical model treatment of the pathology or injury should be accompanied by relief of pain.

The biopsychosocial model

The biopsychosocial model was presented in 1977 in response to perceived shortcomings of the biomedical model and as a means of acknowledging biological, psychological and social factors as determinants of health and disease. It was proposed as … a blueprint for research, a framework for teaching, and a design for action in the real world of health care [15]. Crucially, it acknowledged the reality that illnesses and diseases are human experiences as much as pathological entities.

Pain, a common characteristic of illness and disease, and defined by the International Association for the Study of Pain as An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage is one such experience [16]. Furthermore, chronic pain is considered by some to be a condition in its own right and not solely a symptom of other diseases and injuries [17]. The biopsychosocial model as applied to clinical presentations of pain acknowledges the complex multidimensionality of pain, i.e. the extent to which the experience of pain is determined by the complex interaction of sensory-discriminative, cognitive-evaluative, motivational-affective, behavioural and social dimensions [18]. Risk factors for developing chronic pain, arthritis and overuse injuries in athletes, for example, are similarly biopsychosocial in nature [19–21]. The biopsychosocial model thus invites clinicians to engage with the dynamic interdependent biological, psychological and social dimensions of patients’ pain presentations [8] and to appreciate and better understand the remarkable inter-individual variability of pain experiences [22]. Pain is characterised by biopsychosocial elements across the lifespan [23,24]. Assessing and treating patients according to the biopsychosocial model has been recommended in a number of pain-related clinical guidelines as well as under- and post-graduate pain curricula relevant to physiotherapists [25–27]. It also forms the basis of the World Health Organization’s International Classification of Functioning, Disability and Health [28], and the World Confederation for Physical Therapy (WCPT) specifies that physiotherapy aims to optimise physical, psychological, emotional, and social wellbeing [29], suggesting widespread endorsement of the model.

Criticisms and defence of the biopsychosocial model

Gritti, 2017 [30] has summarised a number of criticisms of the biopsychosocial model, including, that it is vaguely defined, too general and broad or complex and not adequately operationalised or testable as a scientific theory and as such should be regarded only as a general theory or approach to patient care; that it requires the acquisition of wide-ranging time-consuming information from and about the patient that makes it impractical in routine clinical practice; that clinicians are arbitrarily free to emphasise a ‘bio’, ‘psycho’ or ‘social’ approach as it may suit them and that it does not adequately safeguard against the selective dominance or under-representation of any one of the model’s three domains. For example, with respect to its operationalisation, a recent systematic review of guideline-based recommendations for the assessment and management of psychosocial prognostic factors in low back pain (the most common musculoskeletal complaint) found that in general, such clinical guidelines did not provide clinicians with clear instructions about how to incorporate psychosocial factors in LBP care [31]. Others have pointed towards a perceived lack of conceptual clarity in that the model does not adequately explain how the three dimensions interact to effect health and illness [32], that it may encourage compartmentalized thinking [8] or that the biopsychosocial model is often ignored or insufficiently applied in clinical practice and that its composite dimensions are rarely considered as a cohesive whole in most clinical interactions [33].

Assertions regarding some of the weaknesses of the biopsychosocial model have been contested. Gatchel and Turk (2008) [34] counter that data supporting the importance of psychosocial rather than physical factors in the development and persistence of low back pain and disability shows that the biopsychosocial model is a testable (and falsifiable) model. They go on to infer that complex phenomena, such as chronic spinal pain, necessarily require more complex models to explain them and that such complexity should not deter us from attempting to explain it. Evidence supporting the validity and utility of the biopsychosocial model has been summarised, including that it has advanced person-centred care, predicts and accounts for the fact people become ill in the absence of underlying pathology, is used in clinical guidelines and classification systems, and forms the basis of many complex health interventions and informs the management and research of a range of disabling conditions such as chronic low back pain [35].

Understanding and conceptualisation of the biopsychosocial model in physiotherapy

Conceptual models designed to assist clinicians to organise, understand and apply knowledge related to the biopsychosocial model of pain have been described. A detailed description of these is beyond the scope of this paper and interested readers are invited to consult the original works [36]. Briefly, the ‘Mature Organism Model’ and the ‘Biopsychosocial Model of Disability’ are described which allow consideration of the dynamic interactions between various biological, psychological and social/environmental determinants of (ill)health. Models of clinical reasoning are subsequently presented in order to facilitate the organisation and application of this knowledge in clinical practice [36].

Using a ‘concept analysis’ methodology, Daluiso-King and Hebron (2020) [8] sought to understand how the biopsychosocial model is currently understood and conceptualised within the musculoskeletal physiotherapy literature. In addition to confirming an alignment with the bio-, psycho- and social dimensions, their concept analysis identified two additional characteristics in an apparent evolution of the biopsychosocial model within musculoskeletal physiotherapy. Firstly, ‘communication’ was identified as a key feature of the biopsychosocial model through which clinicians come to engage with, understand and know their patients. And secondly, ‘individualised care’ was identified as a means to address the complexity and uniqueness of an individual’s pain experience and tailor management plans accordingly. Both of these attributes, the authors suggest, contribute to building the ‘therapeutic alliance’ between patient and clinician. The authors go on to offer an updated representation of the biopsychosocial model of illness that reflects this expanded understanding of the biopsychosocial model. Others have also found some evidence for an expanded conceptual framework for the biopsychosocial model that includes themes related to individualised care and the therapeutic relationship [37].

Application of the biopsychosocial model in physiotherapy clinical practice

Screening methods to facilitate the identification of psychosocial risk factors in clinical practice, including ‘yellow flag’ screening [38] questionnaires to identify adverse cognitive and affective attributes (such as pain catastrophisation, fear of movement, self-efficacy and depression) and prognostic questionnaires (such as the Keele Subgroups for Targeted Treatment (STarT) Back Screening Tool and the Optimal Screening for Prediction of Referral and Outcome Yellow Flag (OSPRO‐YF)) have been developed and validated [39], although how extensively they are used in clinical practice is uncertain.

However, despite apparent awareness of the biopsychosocial model and the availability of frameworks for its understanding and application, evidence from systematic reviews appears to show varying levels of confidence and proficiency in physiotherapists psychosocially-oriented clinical knowledge and practice. A recent systematic review and meta-synthesis of qualitative studies of physiotherapists’ perceptions of learning and implementing a biopsychosocial intervention to treat musculoskeletal pain conditions found that biopsychosocial-based training helped align some aspects of physiotherapists’ practice with the biopsychosocial approach, promoted a more person-centred outlook and enhanced communication in a way that they perceived helped build a therapeutic alliance [40]. The same review also found that some physiotherapists experienced some professional discomfort when attending to psychosocial factors in what was perceived by some as an extension of their scope of practice. Some physiotherapists found it challenging to learn and apply their training in biopsychosocial approaches. A systematic review and qualitative meta-synthesis of qualitative studies in which physiotherapists were questioned about identifying and managing cognitive, psychological and social factors in people with low back pain found that some i) only partially recognised cognitive, psychological and social factors; ii) stigmatised patients whose behaviour suggested that cognitive, psychological or social factors were influencing their pain as demanding, attention-seeking and poorly motivated; and iii) expressed either reservations about discussing psychosocial factors with patients or concerns regarding a lack of training and expertise and exceeding professional scope of practice [41]. Another systematic review of physiotherapists’ perceptions of and skills in assessing and managing psychosocial factors in individuals with back pain found that while physiotherapists supported the biopsychosocial approach, few are adequately applying it in practice, despite training in cognitive behavioural principles. In addition, physiotherapists expressed some reticence in addressing work-related psychosocial factors, perceiving that such issues were outside their professional role [42].

Additional evidence from survey, observational and qualitative studies of clinical reasoning appears to show varying levels of confidence and proficiency in physiotherapists psychosocially-oriented clinical reasoning, knowledge and practice [43–49]. Together, these findings appear to show widespread acceptance of the biopsychosocial model and that while some physiotherapists were willing to embrace and implement a biopsychosocial approach, and appeared to see the value in doing so, others found this far more challenging. Furthermore, cohorts of physiotherapists appear to consider themselves insufficiently trained to be able to confidently and competently adopt biopsychosocially-oriented approaches in clinical practice. Evidence shows that understanding and application of the biopsychosocial model is inconsistent among physiotherapists. And recent qualitative studies show that both patients [50] and physiotherapists appeared to remain comfortable focusing on the biological aspects of low back pain and that, at least to some extent, the biological focus forms part of physiotherapists’ professional identity [51].

Psychologically informed treatment in physiotherapy

Psychologically informed treatment approaches blend conventional physiotherapy treatments, which typically target biomedical model-based patho-anatomical and mechanical sources of pain and dysfunction with cognitive-behavioural therapies that take account of the potential influences of a person’s thoughts, feelings and behaviours together with wider socio-economic contextual factors [52]. Psychologically informed physiotherapy interventions for a range of musculoskeletal disorders (e.g. low back pain; complex regional pain syndrome) have been developed [53]. Examples of such approaches include graded activity/exposure, cognitive-behavioural and acceptance and commitment type interventions [53,54]. These interventions may be variously delivered as group or one-to-one; face-to-face or online interventions although challenges in implementing such interventions have been identified [55].

Systematic reviews have shown low to high quality evidence that physiotherapist delivered cognitive-behavioural type interventions when combined with physiotherapy may decrease pain in the short and long term and decrease disability in the short term when compared to conventional physiotherapy alone (exercise, multimodal treatment, pragmatic rehabilitation programmes) or usual care. Effect sizes ranged from small to large [56,57]. A recent scoping review suggests a possible explanation for this, that the training therapists received as part of these trials may not have sufficiently facilitated the implementation of skills or techniques to enable the paradigm shift and behaviour change required for physiotherapists to effectively deliver a biopsychosocial intervention [58]. However, given the methods used for the assessment of methodological quality of included studies, inconsistent results and effect sizes the findings from these systematic reviews should be interpreted with caution. Adequately powered, pre-registered, well conducted and reported clinical trials would be useful for investigating the effectiveness of psychologically informed physiotherapy treatment approaches and providing more robust estimates of treatment effect.

What about the ‘-social’?

It has been suggested that the social dimensions of pain, at the individual and societal levels, may be less well appreciated and even ignored by those working within the limits of the biomedical model [59]. Understanding the role of the social environment on human pain perception and how it interacts with the biological and psychological determinants is, it has been argued, necessary in order to advance our understanding of pain, progress our attempts to prevent and treat it [60] and inform public health policy since it has been argued, pain is a ‘sensitive barometer of population health and well-being’ with social causes and consequences [61]. For example, ‘social pain’ such as that experienced through social exclusion may elicit and/or modulate pain sensitivity via shared neural networks [62–64].

A social model of pain, the social communication model of pain, has been described [65]. This model provides an inclusive framework for organizing and considering the dynamic interplay between the biopsychosocial domains and their relationships. It recognises the role of both past and present biopsychosocial determinants of an individual’s pain experience together with those of care givers and others (e.g. clinicians) and ultimately invites clinicians and researchers to consider how people in pain function in complex social environments [66]. If and how this model might be applicable to physiotherapy theory and practice is not known.

A range of social factors are thought to be associated with the development and/or persistence of chronic pain, including levels of social support (higher levels of support has may be associated with better outcomes), socio-economic status (lower socio-economic status has been associated with higher levels of disability and pain) and work related factors (lack of workplace support, higher levels of work dissatisfaction and increased physical demands may be linked to the development of chronic pain) [67]. Other social factors that may affect the pain experience include financial hardship, poor family functioning and involvement in litigation [68]. For example, rates of chronic pain are higher and more burdensome and impactful in people living in areas of socio-economic deprivation [69]. A recent study confirms that levels of ‘physical’ pain in nations appears to depend on the state of the economy, specifically unemployment rates, with increases and decreases in pain associated with corresponding increases and decreases in unemployment rates, raising the questions of if and how economic worry and/or hardship contribute to pain [70]. Furthermore, these increases in pain are experienced disproportionately by women.

Cultural traditions, beliefs, inequalities and prejudices may also impact the pain experience, i.e. of perception, behaviour and treatment, within Indigenous persons, ethnic groups, and marginalized communities [59,71]. Reciprocally, cohort studies from the United Kingdom have shown that musculoskeletal pain, particularly widespread pain, in older adults is associated with increased loneliness and perceived insufficiency of social support and reduced social engagement [24,72].

Limited evidence suggests that the ‘-social’ dimension of the biopsychosocial model may be relatively unattended to within physiotherapy compared to the ‘bio-‘and ‘-psycho’ dimensions. A critical review using qualitative discourse analysis that investigated the concepts and assumptions behind the use of the term ‘biopsychosocial’ in the physiotherapy literature regarding physiotherapists’ assessment and management of and beliefs concerning people with LBP found limited references to occupational, family relationships, social assessment tools, and socioeconomic factors and none regarding class, gender, or political context [9]. It could be speculated that this might reflect a lack of specific knowledge, training or competency in dealing with social factors as they relate to the prevention or persistence of chronic pain. It is also possible that, as with some psychological factors, physiotherapists view social factors as being beyond their scope of practice [51].

Also, uncertainties regarding how and to what extent social factors may be measurable and modifiable may further deter physiotherapists from addressing them. Concerns regarding the evaluation of socially oriented outcomes need not be a barrier within physiotherapy clinical practice since outcome measures that enable clinicians to assess and monitor self-reported social participation and/or pain-related social functioning, such as the Keele Assessment of Participation [73] and the Pain Disability Index [74,75], are readily available and simple to administer. Furthermore, physiotherapists have been advised to discuss potentially unmodifiable social factors openly such that their contribution to an individual’s pain is acknowledged and can be understood [68]. While such openness may enhance the therapeutic relationship and perhaps aid acceptance, the optimal ways for healthcare professionals to assess patients’ socioeconomic circumstances and the potential benefits or harms of such strategies should be investigated [76].

Though awareness and understanding of the social determinants of pain within physiotherapy may be limited the development and evaluation of interventions that target social factors would be innovative. For example, physiotherapists have been encouraged to involve themselves with newer approaches to addressing the social determinants and enablers of health, such as ‘social prescribing’ [77]. ‘Social prescribing refers to the prescription of non‐medical, community or social activities to help people manage and prevent illness and improve their health and well‐being and can involve a range of activities, including physical activity and exercise, such as walking groups [78].

Other promising socio-cultural interventions have also been described, including mass media campaigns to positively change beliefs and behaviours associated with low back pain, occupational interventions to aimed at reducing workplace disability and changing compensation and disability policies to reduce economic costs [79]. State-supported public health campaigns have demonstrably changed societal beliefs and practices, and improved health-related outcomes in a range of settings and contexts [80]. Given the prevalence and societal impact of chronic pain similar interventions could provide a useful adjunct to or substitute for existing medically-driven pain management approaches. Future research may test the clinical and cost effectiveness of such socially driven interventions.

Future directions

The biopsychosocial model has evolved and should continue to do so in light of criticisms of current methods and new knowledge and practices [35]. Although not specific to pain, variations and updates of the biopsychosocial model, both practical and theoretical, have recently been described. The ‘holistic biopsychosocial model of illness’ makes explicit the range of factors may influence behaviour and disability aims to provide a comprehensive understanding of illness and a rational approach to rehabilitation [81]. The ‘diathesis-stress biopsychosocial model of chronic pain’ aims to provide a better understanding of how the biological, psychological, and social factors interact while accounting for predispositional (i.e. genetic, biological, psychological and sociological) vulnerabilities of patients [71]. The ‘Biopsychosocial-Pathways model’ describes causal pathways among biological, psychological, and social factors [32]. Its authors assert that the relationships among the variables are empirically testable and that these relationships are already supported by a large body of evidence. And two recent concept analyses appear to show an expansion of the conceptualisation of the biopsychosocial model in physiotherapy [8,37].

A potential solution to criticism that the biopsychosocial model is too vague and general has been developed. Smith (2021) [82] makes a distinction between ‘general’ and ‘specific’ biopsychosocial models, whereby a patient-centered interview method helps operationalise the biopsychosocial model for clinicians and which then describes the biopsychosocial features unique to an individual patient [83]. Efforts are underway to develop and validate a clinically-applicable tool, the ‘Pain and Disability Drivers Management (PDDM) model’ as a means to identify the domains influencing pain and disability, establish a patient’s biopsychosocial profile (or phenotype) and provide targeted care [84]. Future testing may establish its clinical utility.

A recent systematic review identified a range of barriers and enablers that influence healthcare professionals’ adoption of a biopsychosocial approach to musculoskeletal pain, the majority (46%) of whom were physiotherapists, [85]. Their identification may offer insights for directing future efforts to improve understanding and implementation of biopsychosocial approaches. Some were linked to the professional knowledge and skills of clinicians (e.g. a perceived lack of knowledge of psychosocial factors and/or how to identify or manage them; a tendency towards biomedically-oriented practice; a lack of suitable communication and interpersonal skills; lacking the skills to manage patients’ emotions and beliefs) or to personal factors of the healthcare professionals (e.g. considering it beyond their scope of practice to adopt a biopsychosocial approach; practice grounded within a biomedically-oriented approach; unhelpful beliefs towards biopsychosocial approaches). Others were linked to healthcare professionals perceptions of patient factors (e.g. judgements concerning patients’ social issues, litigation or lack of motivation or, patients’ biomedical focus or expectations) or consultation times (e.g. a perceived lack of time to address psychosocial factors within a clinical consultation).

Additional barriers linked to clinical communities (e.g. the persistence of a biomedical culture in healthcare professions and systems; disagreements and differences between healthcare professionals’ interpretations regarding the type of care required), funding (funding models impacting on the financial feasibility of biopsychosocial approaches), resources (lack of specialist services to support a biopsychosocial approach), training (lack of counselling/psychosocial training to help healthcare professionals apply a BPS approach), healthcare policy (lack of political/regulatory/professional association supports), organisational factors (regulations obstructing the use of a biopsychosocial approach) and social factors (social stigma towards psychological and social services; information spread through mass media that may not be aligned to biopsychosocial models of care) have also been identified [85]. Providing solutions to these many barriers may improve the understanding and implementation of biopsychosocial approaches in healthcare delivery. For example, a recent systematic review found that biopsychosocial focussed pain education strategies can improve the pain related knowledge, attitudes and clinical behaviours of student and qualified healthcare professionals that better aligns with biopsychosocial approaches [86].

Also, the extent to which elements of biopsychosocial based care for pain-related conditions may cause potential harms (e.g. psychological, medical and social) should be considered [87] and may be under-assessed [88]. Future studies and trials of biopsychosocial interventions for patient cohorts in pain should follow recommendations and measure the nature and number of adverse events as co-primary outcomes in order to permit benefit-risk assessments [89,90].

Limitations

Opinion pieces typically present a general discussion of a subject, do not propose or test a hypothesis and do not involve a systematic search or critical appraisal of the literature. As such, this paper presents the perspective of a single author which may reflect a range of potential biases.

Summary

The biopsychosocial model invites clinicians to understand and address the biological, psychological, and social dimensions of patients pain. It has been criticised for being a model without a method. Despite this, it is widely endorsed in numerous clinical guidelines and pain curricula of relevance to physiotherapists. Awareness of the model in physiotherapy clinical practice appears to be broad and some physiotherapists appear to be comfortable learning and implementing biopsychosocial approaches. Despite this a body of evidence suggests that some physiotherapists may have a limited understanding of the model and/or lack the knowledge or confidence to implement it in clinical practice. Barriers to understanding and implementing the biopsychosocial approaches in clinical practice have been described. Addressing these may improve such understanding and implementation. Enhancing operationalisation of and training and education in biopsychosocial approaches and further development and evaluation of the benefits and harms of innovative biopsychosocial-oriented interventions appear to be important ways forward.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Notes on contributors

Keith M. Smart

Keith M. Smart is an academic and clinical physiotherapist with an interest in pain science, practice and education within musculoskeletal physiotherapy.