The Hospital Anxiety and Depression Scale (HADS) is a self-assessment questionnaire used to measure levels of anxiety and depression in individuals who are receiving medical treatment. It was developed by researchers Zigmond and Snaith in 1983 and has since become widely used in clinical and research settings.

The HADS consists of 14 questions, divided into two subscales: the Anxiety subscale (HADS-A) and the Depression subscale (HADS-D). Each subscale contains seven items, and each item is scored on a four-point Likert scale ranging from 0 to 3. The total scores for the anxiety and depression subscales range from 0 to 21, with higher scores indicating higher levels of anxiety or depression.

The HADS is designed to be a brief and simple tool for assessing emotional distress in individuals with physical health problems. It focuses specifically on the psychological aspects of anxiety and depression, rather than physical symptoms. The questionnaire can be self-administered or completed through an interview with a healthcare professional.

It's important to note that the HADS is not intended to provide a definitive diagnosis of anxiety or depression but rather to screen for possible symptoms and provide an indication of the severity of distress. If significant levels of anxiety or depression are identified, further evaluation and assessment by a qualified healthcare professional are recommended.

The HADS has been widely used in various healthcare settings, including hospitals, primary care, and research studies. It has shown good reliability and validity across different populations and has been translated into numerous languages.