The DASS-21 Scale Explained

Most successful projects require a variety of tools, used in combination to achieve the desired end. The same holds true when evaluating new clients. No single data point can accurately inform therapeutic decision-making on its own. Instead, a combination of assessments provides a clearer picture of your client’s current situation and helps you determine how to best treat. 

Today, we’ll be taking a look at one of these tools, the DASS-21 Scale. This rating scale provides therapists with self-reported, objectively-rated information on a client’s current levels of emotional functioning. In this post, we’ll examine all things DASS-21. We’ll dive into what it is, what current research shows about its overall validity, and how to make the best use of it in your own practice.

What is the DASS-21 Scale?

Originally developed by Syd Lovibond and Peter Lovibond at the University of New South Wales in 1995, the DASS-21 is a quantitative measure of distress. It examines three separate, but interrelated areas: depression, anxiety, and stress. Each of the three subscales includes seven items. In the area of depression, the scale measures levels of dysphoria, hopelessness, devaluation of life, self-deprecation, lack of interest/involvement, anhedonia, and inertia. For anxiety, it measures autonomic arousal, skeletal muscle effects, situational anxiety, and subjective experience of anxious affect. Lastly, the stress-related items evaluate difficulty relaxing, nervous arousal, being easily upset/agitated, being irritable/over-reactive, and impatience. Clients are asked to rate each item on a 4-point scale based on what they’ve experienced during the past week. 

The DASS-21 is the abbreviated version of the longer DASS-42, which contains 42 items. As with anything that’s been trimmed down to size, the DASS-21 comes with tradeoffs. The DASS-21 has been shown to yield similar, but minimally less reliable scores than the full version. On the plus side, it can be administered in half of the time. When using the DASS-21, you’ll need to multiply the scale scores by 2 so you can compare the results with the DASS normative data. In general, the DASS-21 is better-suited for research purposes, while the DASS-42 is a more effective instrument for use in clinical settings.

Is the DASS-21 a Valid Measure?

So is the DASS-21 a valid measure that can produce reasonably reliable results? The short answer is “yes.” But let’s take a quick spin through two recent studies that sought to answer this question.

Published in 2017, one study was done in Hanoi and involved 1,745 Vietnamese high school students who were given the DASS-21 to complete. An analysis of the results showed that the measure demonstrated an adequate degree of internal consistency. The researchers concluded that the DASS-21 performed well when it came to assessing the symptoms of depression and anxiety, though its ability to identify stress in the teenage study participants was more limited. 

Another study was conducted by the British Psychological Society in 2005. In this study, the DASS-21 was completed by 1,794 non-clinical individuals who formed a loosely representative cross-section of the UK’s adult population at that time. Researchers found the DASS-21 was a valid measure that accurately assessed the dimension of depression, anxiety, and stress.

How to Best Use the DASS-21

The main advantage of the DASS-21 in a clinical setting is to assist in more accurately locating the source of a client’s emotional disturbance. Its principal use is to identify the primary symptoms of depression, anxiety, and stress. The DASS-21 is a helpful tool to use alongside other data gathered during a clinical assessment and can provide you with valuable insight into a client’s emotional levels of functioning. The DASS-21 can be used as part of an initial clinical assessment and to measure a client’s progress over time. 

Who Can Administer the DASS-21?

Since the DASS-21 is a self-reporting assessment, there are no requirements for who can administer it. However, the interpretation of this instrument should be conducted only by qualified individuals with specialized training in psychology or by certified mental health professionals. The DASS-21 is in the public domain, so there are no special permissions required to obtain copies or administer the assessment. In fact, you can download a copy directly from the University of New South Wales. The accompanying DASS manual contains helpful information on the DASS system, including an extensive amount of material on the theoretical background of the measure, norms, and scoring. The manual costs $55 AUD and can be purchased here.

Wrapping Up

The DASS-21 can provide you with valuable information about the levels of depression, anxiety, and stress that your clients are experiencing. Although it’s not meant to stand on its own when directing treatment decisions, it’s a handy tool that deserves a place in every therapist’s toolbox. 


Ready for an EHR to streamline your practice management?

Start Your FREE TheraNest Trial