Known knowns are the things that we are aware of and understand. An example might be that the volume of patients in a given ED in March 2020 being evaluated s/p minor motor vehicle crashes dropped.

The Value of Analyzing the Known Unknowns

As emergency physicians, we pride ourselves on being ready for anything that rolls through the door. We are not accustomed to asking, “What do we do when the cases we usually handle with ease don’t show up?” We know that volume has dropped, but we can’t easily answer the strategic question, “Will they come back and when?”

This change in volume will require both short-term changes in operational models and portend the need for shifts in business strategy to support a sustainable contract relationship with a hospital in the future. Emergency department leaders may wish to approach this challenge by utilizing a model that was cited by Donald Rumsfeld, a former Secretary of Defense who famously said,

Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones.[i]

Known Knowns

Known knowns are the things that we are aware of and understand. An example might be that the volume of patients in a given ED in March 2020 being evaluated s/p minor motor vehicle crashes dropped. We can be pretty certain that the reason for this drop can be correlated to shelter in place mandates that have closed non-essential businesses and emptied the roads. Facility data can be used to track this phenomenon but can’t provide information as to whether or not other facilities in your area who are under the same local mandate are similarly affected. Aggregated data at a regional or national level is necessary to gain additional insight as to the impact of the local mandates as well as variation changes in volume across facilities. Another valuable question, “If trauma volumes continue to be low, should we terminate our trauma center designation?” moves into the realm of known unknown questions and deeper insight into the data within the context of the community and the facility’s resources.

Known Unknowns

Known Unknowns include things that we are aware of but don’t yet understand. The first step in evaluating the potential effects of the pandemic on ED volume requires identifying and categorizing this information. A good example of a known unknown was pointed out in the New York Times article of April 6, 2020, “Where Have all the Heart Attacks Gone?”[ii] which cited a drop of approximately 30% of ST segment elevation myocardial infarctions (STEMI) across the country. The drop in cases has been verified and is similar to the Italian experience. What is unknown is what are the multiple factors that may be causal in this drop and which ones will be reversed when shelter in place rules are eased or lifted  Efforts to identify similar known unknowns are the first step in predicting what future EM case mix and patient flow may look like.

Developing Insights

A comparison of case-mix data from 1Q2019 and 1Q2020 is a good place to start. A separate comparison of March 2019 and March 2020 will be necessary to set the baseline for trend data that is tracked weekly or monthly. A group may wish to review aggregated case data in a variety of ways. The following is a comprehensive list of potential options driven by demographics, type of visit, process of care, and events.

DemographicsVisitsProcess of CareEvents
AgeFor ambulatory care sensitive (ACS) conditionsArrival by ambulanceReturn to ED within 72 hours
Race and ethnicityFor acute time sensitive conditions including AMI, stroke and SepsisDomiciled in a long-term care facilityReadmissions within 72 hours
DisabilityBy frequent ED chief complaints such as abdominal pain, chest pain, headacheEmergency Severity Index (ESI)Death within 72 hours
SexFollowing falls in the elderlyDischarge by ambulanceChest pain team activation
Zip codeBy types of trauma such as s/p motor vehicle crashDisposition to inpatient unitStroke team activation
For work-related injuriesDisposition to observation staySepsis protocol initiation
For post-inpatient/outpatient procedure complicationsDeath in the EDTrauma team activation

Once leadership has a sense of the impact of the pandemic on any or all of these segments, the next step will be to examine the macro forces driving these changes including the diagnosis and treatment of the virus itself, CMS policy changes, the economic impact on insurance coverage, and quarantine-linked effects. It will only be then, that the work of determining what the scope of work in emergency medicine is and what its economic challenges and opportunities are can be approached.

[i] Rumsfeld, D. United States Department of Defense Briefing. February 12, 2002.  Accessed on April 13, 2020.

[ii] Krumholtz, H. “Where Have all of the Heart Attacks Gone?” New York Times. Accessed, April 12, 2020.