Subjective units of distress scale

Summary

The Subjective units of distress-scale (SUD-scale) is a very useful and straightforward clinical technique in exposure therapy for anxiety. It’s essential element is asking the patient to represent his level of anxiety on a scale (usually from 0 to 100). The SUD scale is indispensable in creating an exposure hierarchy and very useful during exposure.

Principles and practice

In cognitive behavior therapy for anxiety problems, a common clinical technique is using the so-called “subjective units of distress scale” (SUD-scale), sometimes simply called the “anxiety scale”. The therapist presents it in this way:

“I would like to you imagine a scale from 0 to 100, where 0 corresponds to no anxiety at all, and where 100 corresponds to the worst level of anxiety you have ever felt in your life.”

The scale is introduced during an initial session when the patient is not very anxious, to be able to calmly and clearly elaborate on it, so it is fully understood and integrated by the patient. It is often helpful to make the patient reflect upon the “worst level” in more specific terms: “Can you recall when this was, when did you have the worst anxiety ever?”. It is important not to phrase the question as “What is the worst level of anxiety you can imagine?” because that often skews the scale, making it less clinically helpful. That is, it’s important that both the 0 and the 100 in a concrete way is relatable to the patient as something he or she has really experienced. Of course, one can also use a scale from 0 to 10, if it is easier or more relatable to the patient. With a young child, one can use animated faces of anxiety ridden people (from 0 represented by a calm, smiling face, and a 5 represented by a very fearful animated face).

After the scale is established, the therapist can regularly ask: “At what level of anxiety are you now?” to socialize the patient to the scale.

Use in an exposure hierarchy

During an exposure therapy, when the therapist constructs an exposure hierarchy together with the patient (see separate article), the SUD-scale is indispensable. In relation to every example of a phobic stimulus (anxiety related situation or object), the therapist asks “How much anxiety on the 0-100 scale do you think you would feel, if you were fully exposed to it, without safety behaviors, like we discussed before?”

It is very important to explain that what the patient should rate is specifically the fear or anxiety, not the intensity of other, physical sensations. An example in therapy for panic disorder is the exercise of spinning around to create dizziness (see specific article on Interoceptive exposure). Whether we have panic disorder or not, we all will feel (more or less) of dizziness when we spin ourselves on a spinning chair for example. But for most of us, even with very high dizziness, our anxiety level is very low or zero. It is not the intensity of the dizziness that the anxiety scale shall reflect, but specifically the degree of fear/anxiety. Another example in therapy for contamination OCD is the sensation of disgust (see specific article on Exposure and response prevention for OCD). Whether we have obsessive-compulsive disorder or not, we all will feel (more or less) disgust when we are in a public bathroom with a strong smell of urine, for example. But for most of us, we are not afraid of being there - the anxiety level is very low or zero.

Use during exposure

During a therapist guided exposure exercise, the therapist wants to continually assess the patient’s level of anxiety on the SUD-scale, by asking “What is your level of anxiety right now?”. In this way, the therapist can follow the patient’s degree of anxiety during the whole exposure, and see if it descends (which it usually does). This also helps the patient to “stay on track” with exposure, being in touch with his or her anxiety, and not trying to distract from it.

As discussed in the articles on exposure (see specific articles) it is however not important that the anxiety declines during an exposure session (called intra-session habituation of anxiety): We know from research on inhibitory learning (see separate article) that the mechanism of change in exposure therapy isn’t really the habituation of anxiety (even if that most often occurs, especially between sessions, which is called inter-session habituation), but rather that the patient, during exposure, gets an experience of something new.