Clinical Cutoff (or Boundary) Score

The Clinical Cutoff Score refers to a score that is presumed to represent the boundary between "normal" and the "clinical range" on an outcome measure. Jacobson & Truax (1984) describe a method for calculating the clinical cutoff score for outcome measures in psychotherapy research. The formula requires the mean and standard deviation of both a clinical and non-clinical sample, and estimates the score at which a subject has a greater probability of belonging to a clinical sample rather than a non-clinical sample. This method has been widely used and cited in research.

Another frequently used definition of "normal" is a score that falls within 1 standard deviation of the mean for a non-clinical sample. Subjects scoring more than a standard deviation above the mean of a non-clinical sample (85th percentile) are said to be in the clinical range. In practice, both methods tend to arrive at very similar cutoff scores.

It is worth noting that published reports indicate that at least 25% of patients seeking mental health services have test scores below the clinical cutoff score at the start of treatment. Patients with test scores in the normal range tend to have change scores near 0 or even in a negative direction. See Brown et al (2001) for further discussion of this phenomenon.

I have attached an Excel utility to estimate the Reliable Change Index and clinical cutoff score for any outcome measure.

• ACORN_RCI__and_clinical_cutoff_calculator.xls

-- JebBrown - 07 Jan 2007

Primary topics:

• Measure What? Why?
• Global Distress Factor
• Absenteeism & Presenteeism
• Items or Questionnaires?
• Outcomes Measurement 2.0
• Reliability and Validity
• Measurement Error
• Measuring Change
• Regression to the Mean
• Clinical Cutoff Score
• Reliable Change Index
• Effect Size
• Meta-analysis
• Case Mix Adjustment
• Severity Adjusted Effect Size
• Outcomes Benchmarking
• Trajectory of Change
• Random Walk Hypothesis
• Rational Resource Allocation
• Therapist Effects
• Value Index

You may also view all topics in alphabetical order in WebTopicList.