Is your practice really that predictable? Nonlinearity principles in family medicine: these patient cases show "nonlinear" thinking better grasps complexities and handles the unexpected

Journal of Family Practice, Nov, 2005 by David A. Katerndahl

Practice recommendations

* Heighten your awareness of nonlinear patient behaviors including sensitivity to minor changes, resistance to change, sudden dramatic change in behavior, and intermittent catastrophes.

* Nonlinearity means we should expect the unexpected but limit unpredictability through in-depth knowledge of patients and context.

* Reinforce positive attractors, use small well-timed interventions, and encourage healthy variability and nonlinearity.

Had Sir Isaac Newton attempted family medicine, he likely would have been uncomfortable with its nonlinear aspect typified by unpredictable disease courses and treatment responses.

Linearity forms the basis of our knowledge ... Life in a Newtonian world is ordered and predictable, where causes are directly linked to effects and behavior is linear or cyclic (periodic). In this world, stability and predictability define a healthy system. Furthermore, by understanding the parts of a system, we understand the system. As physicians, we are trained to expect this linear, predictable, reductionistic view of health.

... but it does not reflect the human system. However, humans are complex adaptive systems, characterized by multiple interconnected and interdependent parts at levels from the microscopic to the community. Interactions change over time, producing synergistic nonlinear behavior as components periodically self-organize into functional groups.

TABLE 1 compares the Newtonian world view with that of complexity science. Although all of the characteristics of complexity science are relevant to family physicians, this article will focus on the nonlinear behavior of patients as the visible, unpredictable, and often frustrating manifestation of the complexity characteristics. TABLE 2 defines specific characteristics of nonlinearity.

In understanding nonlinearity--as depicted in 4 patient cases presented here--family physicians can learn to * expect the unexpected

* reduce unpredictability by learning about patients and their context

* attack patient resistance by seeking epiphanies or using positive attractors

* recognize the sensitivity of our patients' trajectories and use or anticipate it

* promote the healthy benefits of nonlinearity.

* Nonlinearity as a truer model of health

Although our basic medical knowledge is built on a reductionistic approach that assumes linear dynamics, our models rarely account for more than 30% of whatever outcome we are investigating. Clinical providers are often faced with the unexpected.

Although linearity suggests that illness should respond in predictable ways regardless of the environment, family physicians know that context is critical. In addition, the human condition is often nonlinear; nonlinear dynamics (chaotic or random dynamics) have been documented in physiology, (1) psychology, (2,3) sociology, (4) business, (5-7) and economics. (8)

In fact, nonlinear dynamics are often a sign of health. For example, mood may vary in linear patterns among patients with affective disorders; therapy for mood disorders may work by changing the pathological linear dynamics in mood into more healthy nonlinear dynamics. (9) Linear (or periodic) dynamics often indicate a pathological condition. (10,11)

As science and medicine begin to embrace the nonlinearity of complexity science, we must anticipate, recognize, and apply nonlinearity to the care of our patients. This is particularly important for family physicians.

* Applying nonlinearity to patient cases

The following cases demonstrate characteristics of nonlinear dynamics (TABLE 2).

Case 1: Sensitivity to initial conditions I.C. is a 25-year-old teacher who is 6 weeks postpartum. Recently, while at a local shopping mall, she experienced a sudden onset of chest discomfort, palpitations, dizziness, trembling, and a sense of impending doom. The episode peaked in intensity within 3 minutes and lasted 20 minutes after leaving the mall. Although she has not experienced another attack, she has progressively limited her activities since, until now, she has not been able to bring herself to re-enter the mall for fear of another attack. In fact, she reports intense anxiety in anticipation of possibly visiting the mall and has begun limiting her driving in general.

Agoraphobia is linked to the location and interpretation of the first panic attack. (12) This demonstrates the concept of sensitivity to initial conditions whereby small differences in starting values result in very different behaviors later. In other words, apparently minor differences in a patient's initial physical and emotional state can translate into drastically different outcomes over time.

This emphasizes the need for physicians to pay attention to detail during stressful events that patients experience. For example, if a patient experiences the first panic attack in a self-perceived "safe" environment or interprets the attack as a normal response, she may avoid the disabling consequence of agoraphobia and remain functional. There are other examples of this sensitivity to small changes, such as siblings of similar genetic make-up and environment who exhibit markedly different health as adults may do so because of "minor" life events each experienced.