The Hamilton Anxiety Scale (HAS or HAMA) is a 14-item test measuring the severity of anxiety symptoms. It is also sometimes called the Hamilton Anxiety Rating Scale (HARS).
Purpose
The HAS is used to assess the severity of anxiety symptoms present in children and adults. It is also used as an outcome measure when assessing the impact of anti-anxiety medications, therapies, and treatments and is a standard measure of anxiety used in evaluations of psychotropic drugs. The HAS can be administered prior to medication being started and then again during follow-up visits, so that medication dosage can be changed in part based on the patient's test score.
The HAS was developed by Max Hamilton in 1959. It provides measures of overall anxiety, psychic anxiety (mental agitation and psychological distress), and somatic anxiety (physical complaints related to anxiety). Hamilton developed the HAS to be appropriate for adults and children; although it is most often used for younger adults, there has been support for the test's use with older adults as well. Hamilton also developed the widely used Hamilton Depression Scale (HDS) to measure symptoms of depression.
Hamilton developed the scale by utilizing the statistical technique of factor analysis. Using this method, he was able to generate a set of symptoms related to anxiety and further determine which symptoms were related to psychic anxiety and which were related to somatic anxiety.
Precautions
The test has been criticized on the grounds that it does not always discriminate between people with anxiety symptoms and those with depressive symptoms (people with depression also score fairly high on the HAS).
Because the HAS is an interviewer-administered and rated measure, there is some subjectivity when it comes to interpretation and scoring. Interviewer bias can impact the results. For this reason, some people prefer self-report measures where scores are completely based on the interviewee's responses.
Description
The HAS is administered by an interviewer who asks a semi-structured series of questions related to symptoms of anxiety. The interviewer then rates the individuals on a five-point scale for each of the 14 items. Seven of the items specifically address psychic anxiety and the remaining seven items address somatic anxiety. For example, the third item specifically addresses fears related to anxiety, the fifth item addresses insomnia and sleeping difficulties related to anxiety, and the tenth item addresses respiratory symptoms related to anxiety.
According to Hamilton, examples of psychic symptoms elicited by the HAS interview include a general anxious mood, heightened fears, feelings of tension, and difficulty concentrating. Examples of somatic symptoms include muscular pain, feelings of weakness, cardiovascular problems, and restlessness.
Results
For the 14 items, the values on the scale range from zero to four: zero means that there is no anxiety, one indicates mild anxiety, two indicates moderate anxiety, three indicates severe anxiety, and four indicates very severe or grossly disabling anxiety. The total anxiety score ranges from 0 to 56. The seven psychic anxiety items elicit a psychic anxiety score that ranges from 0 to 28. The remaining seven items yield a somatic anxiety score that also ranges from 0 to 28.
One reason that the HAS is widely used is that reliability studies have shown that it measures anxiety symptoms in a fairly consistent way. The measure's validity has also been supported by research.
Studies have shown that individuals with anxiety disorders score fairly high on the HAS. For example, persons with generalized anxiety disorder and panic disorder tend to have a total anxiety score of above 20 on the HAS. On the other hand, people with no disorder or diagnosis score very low on the HAS.
While there is a tendency for depressed people to also score high on the HAS, some researchers have suggested that anxiety and depression are so closely linked that people can easily score high on measures of both types of symptoms.
