The Fourth Quadrant

Former United States Secretary of Defense Donald Rumsfeld structured our knowledge into known-knowns, known-unknowns and the famous unknown-unknowns, inadvertently providing a great framework for health. For some reason, he missed the unknown-knowns, presumably the things we don’t know, but that others do.

This Fourth Quadrant is the big challenge in healthcare – we can’t do anything about the things we don’t know we don’t know, but the systems we have keep us reasonably well informed about the things we do know. Moreover, doctors are surprising good at assessing the risk of how, what we know we don’t know will affect the prognosis. The frustration is the unknown-knowns; the lab result that is stuck in the system – somebody knows it, but not the doctor or the patient who has been admitted to hospital but whom the local practice is still trying to medicate at home. Someone knows the INR level but not the practice nurse who is waiting with the algorithm to adjust the dosage.

And the unknown-knowns extend further. Nearly 20 years ago, two journals reported on a standard industrial approach that was used to explore patient flows through hospitals – one included connections to intermediate and social care, and one focused on A&E (Wolstenholme (1999) System Dynamics Rev 15 (3):253-271 and Lane et al (2000) J. Operation Res. Soc. 51 (5): 518–531). They reported the same method – System Dynamics – and both adopted a policy perspective. Between them they offered what we recognise as a surprisingly modern set of observations and recommendations:

  • There is some scope for improving A&E departments through better design.
  • The main impact of running low on available beds is less on A&E and much more on elective surgery and operations cancelled.
  • A&E policies based on a single measure will tend to shift the problem around the system, rather than improve the situation.
  • Measures to improve flow through hospitals yield much better returns than increases in bed capacity.

It is not just David Lane or Eric Wolstenholme who had worked these principles out, most bed managers would have had an intuitive grasp of them. But what if our healthcare planners had really understood? Surely, over the past two decades, discharge services as fancy as any clinical laboratory system would have emerged to wing patients on their way, and instead of shiny new urgent care capacity at the front of so many district general hospitals, we would now have intermediate care facilities and better connections to social care.

Perhaps the Fourth Quadrant is telling us that time is up for the luxury of not knowing what everyone else knows.