The phrase "a diagnostic category" is correct and usable in written English.
It can be used in contexts related to psychology, medicine, or any field that involves classification of conditions or symptoms.
Example: "In the DSM-5, depression is classified as a diagnostic category that encompasses various subtypes."
Alternatives: "a diagnostic classification" or "a diagnostic label".
As recently as thirty-five yeago anxietyxiety did not exist as a diagnostic category.
Darian Leader's Strictly Bipolar (Penguin) is a passionate attack on the rise of bipolarity as a diagnostic category.
Mr. Baron-Cohen states, "Psychiatry is not at the stage of other branches of medicine, where a diagnostic category depends on a known biological mechanism".
Arguing against the usefulness of binge eating disorder as a diagnostic category are some studies that suggest that the condition, as defined in the diagnostic manual, responds to virtually any type of treatment, including no treatment or treatment with sugar pills.
The other books on the list are Henry Marsh's memoir of being a neurosurgeon and Marion Coutts's The Iceberg about her husband's death from a brain tumour, Alice Roberts's exploration of human development from conception to birth, The Incredible Unlikeliness of Being, and Scott Stossel's study of an ailment not even recognised as a diagnostic category a generation ago, My Age of Anxiety.
These are defined as an algorithmic combination of several criteria that lead to a diagnostic category (see cebm.net).net
The removal of mania as a diagnostic category represents a major change in our dimensional model of the mood spectrum.
Grading is the process of subdividing a diagnostic category to increase the amount of information in a histopathology report and so assist clinicians in making individual therapeutic decisions.
The recently developed Acute Physiology and Chronic Health Evaluation (APACHE) IV score and Simplified Acute Physiology Score (SAPS) 3 now include liver transplantation as a diagnostic category.
While homosexuality was removed from the DSM as a diagnostic category in 1973, transsexuality was added in the 1980 DSM-III.
A new approach to these is needed: here we introduce, and investigate, a diagnostic category termed "undifferentiated headache" (UdH), defined in young people as recurrent mild-intensity headache of < 1 h's duration.
