Diagnosis Tool

Learning Objectives

• To critically examine the purpose of a diagnosis.
• To understand what may qualify a behaviour as “abnormal.”
• To practise discussing thresholds for mental health diagnosis.

Materials

• An instructor computer and projector for introducing the tool.
• Student phones or computers for working with the thresholds.

Overview

Students take the role of a clinical committee deciding how to diagnose a fictional Stress Regulation Disorder. Their goal is to decide where to set symptom cutoffs so that the diagnosis identifies people who need clinical intervention, while observing how small changes in a cutoff can produce large changes in prevalence.

The fictional disorder

Stress Regulation Disorder involves ongoing difficulty coping with academic or daily demands. It is intentionally fictional, avoiding the confusion and complexity that may arise from changing the criteria for a real condition.

A diagnosis is given when a person meets two or more symptom cutoffs. Each symptom is measured on a severity scale from 0 to 10.

• Excessive worry: frequent uncontrollable worry about everyday responsibilities and difficulty “turning off” thoughts.
• Low motivation or emotional exhaustion: feeling physically or mentally exhausted most days.
• Sleep disruption: difficulty falling asleep, staying asleep, or feeling rested.

Introducing the tool

Begin with the one-dimensional view, then move to two dimensions and finally three. The increasing complexity is useful: part of the point is to experience how difficult it can be to establish thresholds as more variables are involved.

• Set all criteria to 7. Record the percentage diagnosed and which cases are included.
• Set all criteria to 4. Again record the percentage diagnosed and which cases are included.
• Compare what changed and what those changes would mean for a clinical service.

Establishing thresholds

Assign each group one of the following service priorities. They should choose cutoffs that match the priority and be ready to explain their decisions.

• Limited resources: the service has limited staff and can treat only the most severe cases.
• Balanced approach: identify people with a clear clinical need without overdiagnosis.
• Early intervention or prevention: catch symptoms early, before they increase in severity.

Debrief & discussion questions

• What cutoffs did you choose, and what percentage was diagnosed?
• How did your service priority affect your decisions?
• Do many individuals appear close to the cutoff boundaries?
• Do you see separate “healthy” and “clinical” clusters, or a more continuous cloud?
• Would someone immediately above and below a cutoff necessarily be very different?
• What problems occur if diagnosis is based only on numbers?
• What other information should a clinician consider, including distress, functional impairment, duration, and context?

Take-home message

• Many symptoms exist on a continuous distribution, while diagnostic categories require cutoff decisions.
• Small threshold changes can produce large changes in prevalence, and people near the cutoff may be very similar.
• Symptom counts matter, but the most important question is how symptoms affect a person’s life and everyday functioning.