Let’s be clear. Twenty-first century medical science has produced some amazing advances. Yet in many respects, it remains centuries behind modern science. That’s because medicine’s basic conceptual (theoretical) adherence to disease-only care fails modern scientific standards. Let’s see how.
There are, very broadly, two dimensions of science.1 The first one is the scientific method describing how to conduct research. Researchers deploy it hundreds of times each day. A typical method in medicine evaluates a group of patients to answer a “research question” the scientist poses. For example, “…is drug ABC effective in treating diabetes…” Two groups are compared to each other, one receiving treatment and the other not receiving it (the control group). This research has led to many treatment advances. No one faults medicine’s skills with scientific method.
The method, though, does not indicate what questions scientists should ask to guide the research. Instead, theory tells researchers what question to study,1 of course mirroring how scientists think about their discipline in other areas such as teaching and patient care. Theory typically is well ingrained and seldom even consciously considered.
Until recently, all sciences (including medicine) were guided by the powerful reductionistic theoretical concepts developed during the 17th century Enlightenment. In the 20th century, however, the non-medical sciences embraced a new theoretical approach—a systems view. Examples are general systems theory in biology, cybernetics in mathematics and engineering, and complexity theory and fractal geometry in nonlinear systems.2 Systems ideas paved the way for some of the most dramatic changes of the 20th century, from relativity and quantum theories to computer science to artificial intelligence to gestalt psychology to modern ecology. All sciences adopted a systems perspective—except medicine.
Perhaps the systems approach could be used in medicine? The systems model most applicable to medicine, general system theory (GST), highlights the “holistic” viewpoint that we understand the object of study as a whole entity, rather than the “reductionist” view that the whole can be understood by studying just its individual parts. Applying this view to people, the question becomes, can we understand the health problems of a person (patient) just by studying their body parts in isolation?2 Let’s see how GST answers. GST involves the person level as one part of an expansive hierarchy of natural systems, each system progressing in complexity from subatomic particles to atoms to molecules to cells to tissues to organs to body systems to the person to the family to the community to the society to the cosmos. The figure portrays the continuum of the individual system levels applicable to medicine. Each of these stable levels is structurally and functionally interconnected.
Source: Robert C. Smith
Each system level is composed of many items from the level immediately below, its parts. As well, multiples of the first level become the parts producing the new level just above. The individual parts at one system level interact in unique, unpredictable ways to form the new (unpredictable) whole at the next system level. For example, common experience tells us that simply knowing each individual member of a family in isolation cannot predict the family structure and dynamics because you don’t know how they interact. Similarly, a cell is more than just an addition of its constituent mitochondria, organelles, nucleus, and other parts.
Multiple interacting system levels define any given scientific discipline, the level most central the focal point of the science. For example, a physicist would be familiar with quarks, subatomic parts, and atoms; an anthropologist with communities, culture, and society; and an astronomer with the earth, sun, and Milky Way.
Where, from the figure, might the science of medicine fit in the systems hierarchy? Its focal point is the human being it is charged to care for, the individual person level, the patient. Equally appropriate foci are adjacent areas to the person level: the biological systems just below and the social systems above. While individuals in medicine may specialize at one system level, such as the cell biologist below the person level or the anthropologist above, the medical profession as a whole must have equal representation of all three levels in research and teaching and patient care. Only in this way can medicine best address its primary focus, the patient. I have labeled these levels BIO, PSYCHO, and SOCIAL in the figure to indicate how the biopsychosocial (BPS) model is a special application of GST for medicine, the BPS model also depicted in the other figure.
Biopsychosocial Model of Health 1
In 1977, George Engel described the biopsychosocial model with the intent that it would not only enhance medicine’s scientific status but also its humanistic orientation.3 He sought to integrate the psychosocial dimension of patients with their disease information (the biological systems level of the BPS model). The model then spawned considerable, largely observational research showing prominent scientific benefits from integrating psychosocial and biomedical data. For example, including these data is associated with better health outcomes (such as improved mental and physical health, improved physical function, decreased symptoms, decreased pain, improved survival in cancer patients, and improved control of hypertension and diabetes); improved patient satisfaction and adherence to treatment recommendations; and fewer malpractice suits.
Progress followed with the BPS model contained in many mission statements and acknowledged in some teaching. Nevertheless, the BPS model has had relatively little impact on medicine, in part, because many voiced legitimate scientific concerns:4 the model seemed to advocate that physicians obtain all BPS information about every patient, which would be unnecessary and time-consuming; and the model could not be defined for the individual patient, precluding testing and making predictions to test its scientific mettle.
These concerns telegraph the basic shortcoming in the BPS model. The model advised only “what” we needed to know. It omitted “how” we were to obtain key BPS data. Without a method to answer how, one cannot define the model. As well, to have a scientific method, the model must identify only relevant biological (disease), psychological, and social data—as well as reflect BPS content varying over time.
How do we garner BPS information? The primary method is talking to the patient (the medical interview). Before Engel, the usual way to interview the patient was the so-called clinician-centered interview where the physical disease-focused clinician controlled the interaction, asking repeated questions to diagnose possible diseases. Eliciting the human dimension (psychological or social concerns) was side-stepped rather than encouraged. Engel and others soon recognized the need to develop a better interview if we were to obtain pertinent BPS data.
Levenstein, McWhinney, and colleagues identified what they called the patient-centered interview.5 Integrated with the clinician-centered interview, the patient-centered interview contrasted with the latter’s isolated use. Clinicians now began an interaction by seeking to understand patients’ interests and ideas, which leads to the psychological/mental and social information required by the BPS model. Not interrupting the patient and asking open-ended questions are key skills in eliciting the broader psychosocial factors that might be relevant to the patient’s health concerns and outcomes.
Further progress followed and patient-centered interactions were advocated by many, including the Institute of Medicine. Still, scientific concerns abounded. Many noted the field’s inability to define the patient-centered interview (and, therefore, the BPS model) and provide explicit directions for its conduct. Unable to define the interview, the field could focus only on non-interventional (observational, descriptive) research and teachers relied on their own highly variable interpretations for their patient-centered interviewing instruction.
Experts advised that we needed to know exactly what to say to be patient-centered if we are to improve teaching, patient care, and research. This meant identifying a detailed, behaviorally-defined method, one that produced a clear, yet flexible means to enable researchers and learners to elicit the unique personal and social aspects of their patients. Richard Frankel and I independently developed similar behaviorally-defined methods for the patient-centered interview in 1996, later demonstrating they were easily learned in randomized controlled trials.4 My Michigan State group later showed that our method was associated with improved mental and physical health outcomes in two more randomized controlled trials.4 Our behavioral method included multiple definable skills that were grouped, sequenced, and prioritized to guide the clinician through the interview while not prescribing rote performances. Now published in its 4th edition as a textbook (with accompanying demonstration recordings),6 its easy learnability has recently been confirmed in another controlled trial.7
A behaviorally-defined patient-centered method depicts the basic infrastructure required for a scientific interview, one that produces not just disease data but also the personal, emotional, and relational aspects of its subject—the patient. While specific BPS information will vary from patient to patient, these data will be collected in the same way every time. Systematically defining the biological, psychological, and social information of patients with a repeatable interview provides the consistent, reliable scientific approach needed for rigorous research and teaching. Meeting a practical need, most clinicians require no more than three to five minutes to deploy the patient-centered component. (The usual clinician-centered component follows to pin down details, now of mental as well as physical disorders.)
As a result of the work of many in the field since 1977, Engel’s initial inchoate BPS model has matured to become scientific. Indeed, we now can define it for each patient as the efficiently produced, relevant data from evidence-based patient-centered methods. Further, the BPS model and the interviewing method coalesce as one and the same, the inseparable content (what) and process (how) sides, respectively, of the same coin.4
While other sciences have eschewed the effete reductionistic ideas of the 17th century in favor of systems-based theory, medicine has not done so and pays for it dearly in its scientific reputation because of the embarrassing crisis it has created in mental health care. The GST-based biopsychosocial model, operationalized by evidence-based patient-centered interviewing methods, gives us a proven, ready-to-use theoretical model. Adopting it will vastly improve mental and physical health care, simultaneously making medicine more scientific and more humanistic.