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As a healthcare delivery scientist, you will ask fundamental questions about whether interventions in healthcare made a difference for your patients and your organization. But how can we evaluate these interventions? The examples in Chapter 1 demonstrated what happens when we make the fundamental and human mistake of taking an oversimplified approach to healthcare. Human beings look for patterns and metaphors to explain large, complex problems. Our very tendency to look for coincidence reflects our natural ability to anchor ourselves onto events that we can easily explain. However, these reductionist biases lead us to either assume the innate utility of our interventions without studying them, or when we do study these interventions, to use designs (such as pre/post comparisons) that may lead us to think that our interventions work when they don’t.

Healthcare systems are complex adaptive systems (CASs). In this chapter, we will first look at the downside of oversimplifying healthcare. Second, we will dissect the concept of a complex adaptive system and learn why this is useful in healthcare delivery science. Third, we will look at the key features of a complex adaptive system to understand how this will structure our approach to understand healthcare delivery.

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A complex adaptive system describes a series of interconnected, heterogeneous components of a whole that change and alter in nonlinear ways.


Complicated and complex systems are not the same thing.1,2 A complex system is one that resembles a living organism. The more we examine that system under a microscope, the more we discover. In short, the whole of a complex system is greater than the sum of its parts. We will explore the elements of a complex system throughout this chapter. A complicated system, however, can be unwound into individual pieces that can be understood. The internal combustion engine appears impressive and has transformed human society. But it can be taken apart. An engine can be disassembled into small, understandable pieces. A complicated system is exactly the sum of its parts.

In healthcare, there are systems that are strictly complicated. Take as an example the process of inserting a central line, a large-diameter, venous catheter that is placed into a large, central vein in a patient to provide intravenous (IV) medication. We regularly perform this procedure, and if done incorrectly, it can lead to a high risk of infections and other life-threatening complications for a patient.3 For a doctor in training, this appears to be a daunting task, not least because these types of catheters are usually placed in patients who are critically ill. But the procedure itself can be broken down into a series of very specific steps. First, we gather together the necessary supplies. Second, we get the patient into the right position and make sure that he or she is ...

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