Because we cannot yet diagnose and monitor most mental illnesses through physical means such as functional imaging, genetic testing, or blood serum tests, rating scales are important clinical aids to mental health care. Individual item responses on a standardized rating scale can be used to guide a clinical conversation (e.g., “You indicated that you sometimes have thoughts that you would be better off dead. Can you tell me more about that?”). Numerical scores on rating scales identify symptoms, guide diagnostic assessments, establish the severity of a disorder, and track the progress of patient care. Collecting these scale results over time will also enable measurement-based care, which refers to adjusting a patient’s treatment plan until a measurable symptom target is reached.

We follow a few principles when considering how to use rating scales:

• Select scales that are research validated for age, condition, language, and (ideally) culture.
  
• Use broad-based screening scales to detect the likelihood of any disorder being present.
  
• Use a more specific rating scale to investigate a particular problem.
  
• Select brief rating scales to enhance patient cooperation and ease of implementation.
  
• Reserve longer rating scales for specialty settings.
  
• Remember that rating scales cannot make diagnoses—they are aids, not replacements, for clinician assessment.
  
• Recall that rating scale results depend on the reliability of the reporter and his interpretation.

There are hundreds of rating scales available; to assist your practice, we have listed in Table 12–1 the scales that we find especially helpful in the evaluation and care of older persons with mental distress. Many of these rating scales are (or can be) built into an electronic health record, which allows you to follow a patient’s condition more objectively.

In addition, DSM-5 provides severity rating scales for many disorders. Most are specific to a particular disorder, and some include a narrative description to indicate that a particular disorder is mild, moderate, or severe. For some diagnoses, such as alcohol use disorder, severity depends on the number of criteria endorsed by a patient. For other diagnoses, such as a neurocognitive disorder, severity is measured by the degree to which a patient requires support. When appropriate, the severity ratings refer to specific measurements external to the mental status examination. For example, grading the severity of central sleep apnea depends, in part, on the extent of associated oxygen desaturation.