I recently woke up on a Sunday morning to a flat tire. Although I was able to install the spare tire (were the lugnuts this tight when I was younger?) and plan to have the flat fixed at the service station in town during the work week, we had some decisions to make about using the car without a spare tire. When my spouse asked if the car was OK to drive to get groceries in town a mile away, I said there was no problem. Later in the day when we wanted to visit some friends 45 minutes away, we decided we should not use the car for that. Our decision lay in our personal tolerance for risk and reminded me of the ever-present similar calculations we and our patients have been making about COVID-19.

Let’s break down the flat tire problem and then I’ll apply it to risk assessment in disease. Risk of harm is never taken in isolation but rather as a larger assessment in the context of a benefit.  With our flat tire, the primary risk was that if we got another flat tire (albeit a low probability event), we wouldn’t have a spare to get us back on the road.  A trip to a nearby grocery store probably wouldn’t leave us stranded, but for a flat 25 miles from our house, the consequences would be more significant. We would likely have to have the car towed to a service station where on a Sunday we may not be able to have the tire fixed or replaced. At the same time, the benefits of getting groceries were significant – we had nothing for lunch or dinner for the week.  Seeing friends, while lovely, was lower down on our Maslow’s hierarchy of needs. For us at that particular time, the harms to benefits ratio clearly favored feeding our family but not for seeing far-away friends.

Harms vs Benefits

The key to understanding our decision (which may have been different than yours) was by recognizing the ratio of the potential harms and benefits, not simply thinking of them in isolation. 

Changing some of the conditions also could have changed the calculus of the relative harms and benefits and therefore our decision. What if the spare tire I had installed had no tread left and it was snowing out? What if we decided that the probability of getting another flat was remote? What if rather than visiting friends, we wanted to see a family member we had not seen in 2 years because of COVID-19? Our dynamic appreciation of those harms and benefits affects our willingness to use the car without a spare. 

This is where the ethical principle of proportionality can help us understand both how to make hard decisions as well as how our patients make them. People weigh not just the absolute risks of harm or benefit, but whether or not they are proportional. Large risks of harm are generally balanced by large potential benefits. The risks of dialysis are acceptable to patients because of the tremendous benefit of life-saving treatment. The risks of a ureteroscopy for a patient with significant pain from a ureteral stone are often acceptable to both patient and surgeon if it promotes the promise of better and faster pain control.    

This article originally appeared on Renal and Urology News