The standard diagnostic tests for delirium are called the bedside tests of attention, because inattention and disorganized thinking are the central hallmarks of delirium. These tests specifically target those two domains of confusion. We generally recommend taking a stepped approach to using these tests.
My clinical work primarily is on the inpatient side of Oregon Health & Science University Hospital as a member of their inpatient geriatrics consult team, but primary care physicians can use these tests, consultants use these tests, residents should be taught to use these tests, and faculty can use these tests. They are geared for clinicians at all levels of training and in all different disciplines to help them look for delirium.
The first thing that I do for every patient who I'm suspicious might be delirious is I try to assess their social attentiveness. So I always knock loudly on the door, and I'm looking for their reflexive stare to the door. It's our reflex to look toward noises when we can't see what caused them. Then, I engage in a little bit of chitchat upfront. What I'm looking for is the ability to engage, even just with facial expressions, during that banter.
Then I move on to the more standard bedside tests of attention. My first step is to use the days of the week in reverse and/or the months of the year in reverse. The reason I like these so much is that they are really independent of literacy, so for patients who may have low literacy, low education levels, or even for whom English is not their first language, most will know the days of the week and the months of the year. I ask them to tell me all the days of the week starting with Sunday. I ask for them forward first, and then I ask for them in reverse, starting with Saturday. And sometimes if patients need help, I'll say, “OK, let's start with Saturday. What comes before Saturday?”
Then I move on to a third level, which is the “Casablanca” test. This is a test of attention, stolen from one of the 30-point cognitive inventories for dementia. I tell the patient, “I'm going to read a series of letters, and every time you hear the letter ‘A,’ I want you to clap your hands.” Then I spell “Casablanca.” I go about one letter per second, so that way people can hear and process and clap. If they miss one “A,” that's considered a positive test.
Then I move on to the serial sevens, which is also a test of attention taken from one of the 30-point cognitive inventories, or I move on to them spelling “world” or “earth” in reverse. Stepped tests are helpful for those patients who may be really highly educated, and cognitively sharp, at their baseline. I'm thinking former physicians, former nurses, PhDs, lawyers. I'm priming the pump with the easier tasks. Then making it harder can provoke that underlying inattention to come out in some of those patients where the signs may be more subtle.
If you are able to provoke inattention and provoke that disorganized thinking, you've basically met criteria for acute encephalopathy or acute delirium. You can feel reasonably comfortable making a formal diagnosis even from that very quick bedside exam. You want to put it together, of course, with collateral history from your nursing staff and other clinicians who may be involved in the patient's care, because what you're looking for is, is this an acute change from baseline? And is this person fluctuating, meaning are they having good moments and bad moments over the course of the day? If you've got all of that together, you've got a slam-dunk diagnosis of delirium.