Australia uses three different depression screening tools widely in general practice and mental health services: the PHQ-9, the DASS-21, and the K10. They all measure depression, but they serve different purposes, score differently, and are used in different contexts. This guide explains the differences and helps you know which one to use.
The PHQ-9 was developed by Spitzer, Kroenke and Williams (2001) at Columbia University. It contains 9 questions, takes under 2 minutes, and scores from 0 to 27. Each question maps directly to one of the nine DSM-5 criteria for major depressive disorder, which makes it the most clinically precise of the three tools.
The PHQ-9 is widely used in Australian general practice, especially for monitoring treatment response — because it directly corresponds to diagnostic criteria, it is very sensitive to changes in depression severity over time. A score of 10 or above is the commonly used cut-off for clinically significant depression warranting treatment.
It also includes a critical Question 9 about thoughts of death and self-harm, which means any score above zero on this question triggers a clinical response regardless of the total score.
The DASS-21 was developed by Lovibond and Lovibond (1995) at the University of New South Wales. It contains 21 questions covering three separate subscales: depression (7 questions), anxiety (7 questions), and stress (7 questions). Each subscale produces its own score, doubled to match the longer 42-item DASS.
The DASS-21's strength is breadth — it tells you not just whether you have depressive symptoms, but how they sit in relation to anxiety and stress, which often co-occur. This makes it particularly useful as an initial screening tool and for people who aren't sure what they're experiencing.
The DASS-21 is widely used in Australian research and clinical settings but is not as directly linked to DSM-5 criteria as the PHQ-9, which means it is slightly less useful for formal diagnosis tracking. For depression specifically, a DASS-21 depression subscale score of 10+ (which translates to 20+ on the full DASS) indicates moderate-to-severe depression.
The K10 was developed by Kessler and Mroczek (1994) and later refined with Australian norms. It measures general psychological distress rather than specific diagnostic categories. 10 questions, scoring from 10 to 50, with higher scores indicating greater distress.
The K10 is notable because it is used by Services Australia (Medicare) as part of the Better Access initiative and the Mental Health Treatment Plan (MHTP) assessment process. A K10 score of 22 or above is the commonly cited indicator for clinically significant psychological distress in Australian healthcare settings. GPs often administer the K10 as part of a mental health review.
| Feature | PHQ-9 | DASS-21 | K10 |
|---|---|---|---|
| Questions | 9 | 21 | 10 |
| Time | 2 min | 5 min | 2 min |
| What it measures | Depression only | Depression + Anxiety + Stress | General psychological distress |
| Scoring range | 0–27 | 0–42 per subscale | 10–50 |
| Clinical cut-off | 10+ (moderate) | Depression 10+ (moderate) | 22+ (likely disorder) |
| Maps to DSM-5? | Yes — directly | Partially | No — distress only |
| Used in Medicare MHTP? | Used clinically | Common in practice | Referenced by Services Australia |
| Best for | Tracking depression severity; GP appointments | Initial broad screen; research | Medicare claims; general distress |
| Developed in | USA (2001) | Australia (1995) | USA/Australia (1994) |
Of the three tools here, K10 and DASS-21 are the pair Australian GPs and psychologists reach for most often, so it's worth a direct comparison. The K10 is shorter (10 questions vs 21) and measures a single number for overall psychological distress over the past 4 weeks — it doesn't tell you whether that distress is more depression-shaped or more anxiety-shaped. The DASS-21 takes a bit longer but splits its result into three separate scores (depression, anxiety, stress), which is more useful if you want to understand which specific area is driving how you feel. In short: K10 for a fast general check-in, DASS-21 when you want to know what kind of distress it is. Many GPs use K10 as the quick first pass and follow up with DASS-21 or PHQ-9 if the K10 score is elevated.
Take the K10 or the DASS-21 directly — both are free, take under 5 minutes, and results stay on your device.
In practice, most Australian GPs are familiar with all three tools. The K10 is often administered by GPs themselves as part of a mental health review. The PHQ-9 is widely used in GP software and for tracking treatment response. The DASS-21 is commonly recommended to patients as a self-assessment tool.
The most practical answer: take whichever one you've completed. A score from any of these tools is clinically useful and will help your GP understand your symptoms. If you want to be thorough, take both the PHQ-9 (depression) and GAD-7 (anxiety) — they were designed as a complementary pair and together take under 5 minutes.
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See also: Understanding your DASS-21 results in detail →
Medical Disclaimer: This article provides general educational information. These screening tools are not diagnostic instruments. If you are in crisis, call Lifeline 13 11 14 or Beyond Blue 1300 22 4636 (24/7).