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Outcome assessment tools

What are outcome assessment tools?

Standardised assessment tools are vital for assessing a range of variables including symptoms, functioning and quality of life. They are often used within a controlled research environment, but high-quality assessment tools are also useful in practice for both clinical management and outcome prediction.

The quality of assessment tools can be measured in various ways. ‘Reliability’ refers to the reproducibility of an instrument’s results across different assessors, settings and times. ‘Construct validity’ is the extent to which an instrument measures the theoretical construct it was designed to measure. This involves ‘convergent validity’, which is the degree of correlation between different scales measuring the same construct, confirming they are measuring the same thing; and ‘divergent validity’, which is the lack of correlation between scales measuring different constructs, confirming that they are measuring different things. Similarly, ‘known groups’ validity’ is the extent to which an instrument can demonstrate different scores for groups known to vary on the variables being measured. ‘Content validity’ is the extent to which each individual item on a scale represents the construct being measured, and ‘internal consistency’ is the degree of correlation between individual items within a scale.

‘Predictive validity’ refers to sensitivity, which is the proportion of correctly identified positives, and specificity, which is the proportion of correctly identified negatives. Sensitivity and specificity are measured by comparing an instrument’s results with known ‘gold standard’ results. ‘Responsiveness’ is the extent to which an instrument can detect clinically significant or practically important changes over time, and ‘area under the curve’ (AUC) is a global measure of test performance.

What is the evidence for outcome assessment tools?

Moderate to low quality evidence finds patient-rated measures with the highest clinical utility for assessing symptoms were the Altman Self-Rating Mania Scale, the Quick Inventory of Depressive Symptomatology–Self Report and the Internal State Scale. Clinician-rated measures with the highest clinical utility for assessing symptoms were the Bech-Rafaelsen Mania Rating Scale, the Quick Inventory of Depressive Symptomatology, and the Bipolar Inventory of Symptoms Scale. Electronic self-monitoring of depression but not mania symptoms was found to be reliable, being similar to clinically rated instruments (Montgomery Asberg Depression Rating Scale, the Hamilton Depression Rating Scale or the Inventory of Depressive Symptomatology).

The most commonly used scales for assessing functioning in people with bipolar disorder were the Global Assessment of Functioning and the Functional Assessment Short Test.

June 2020

Last updated at: 1:21 am, 22nd June 2020
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