Tracking Treatment Response to Ketamine: PHQ-9, MADRS, and Clinical Scales

Tracking treatment response to ketamine works best when the same validated measures are collected at baseline and at planned follow-ups, then interpreted alongside safety, function, and clinical assessment. Ketamine-related symptom changes can occur quickly and may change between sessions, so a single impression can miss an improving, plateauing, or worsening pattern. A practical core set is one depression scale, plus suicide-risk, anxiety, pain, or dissociation measures when they are relevant to the individual.

Scores support clinical conversations and treatment planning. They do not replace urgent assessment when someone reports worsening suicidal thoughts, severe distress, or other safety concerns.

Choose one primary depression measure

The Patient Health Questionnaire-9, or PHQ-9, is a nine-item self-report questionnaire for depressive symptom severity. It is brief, widely used, and available without a licensing fee. Its standard instructions ask about the prior two weeks, which can make it less precise for describing changes immediately after a treatment. According to the original PHQ-9 validation study, scores of 5, 10, 15, and 20 represented mild, moderate, moderately severe, and severe depression thresholds in the study population. Kroenke and colleagues published the validation study in the Journal of General Internal Medicine.

The Montgomery-Asberg Depression Rating Scale, or MADRS, is a 10-item clinician-rated measure developed to detect change in depression severity. Ketamine trials often use it as a primary outcome, which can make it useful when a practice wants to compare its approach with published research. It takes more staff time and requires consistent administration. The original MADRS paper describes the scale and its sensitivity to antidepressant-related change.

The Quick Inventory of Depressive Symptomatology Self-Report, or QIDS-SR, is a 16-item self-report measure scored from 0 to 27. It can be a useful middle ground when a practice wants more symptom detail than the PHQ-9 while keeping patient completion practical. The QIDS psychometric evaluation reports its use for measuring depressive symptoms in people with chronic major depression.

Do not switch scales mid-course unless there is a clear reason. A PHQ-9 score and a MADRS score are not interchangeable, so the most useful comparison is usually each patient’s change from their own baseline on the same instrument.

Add measures that answer a specific clinical question

The Columbia-Suicide Severity Rating Scale, or C-SSRS, is a clinician-administered tool for assessing suicidal ideation and behavior. It can provide a structured baseline and follow-up record when suicide risk is part of the presentation. The scale should support, not delay, a full safety assessment and appropriate urgent care when needed. Posner and colleagues described the development and initial validity of the C-SSRS in the American Journal of Psychiatry.

The Generalized Anxiety Disorder-7, or GAD-7, is a brief self-report measure of anxiety symptoms. A pain rating such as a 0-10 Numeric Rating Scale may be relevant when pain is also being followed. The Clinician-Administered Dissociative States Scale, or CADSS, measures dissociative symptoms around treatment and may help document tolerability. Add a measure because it changes care, not simply because it is available.

For context on what a changing score may mean between sessions, see how long ketamine effects may last. Readers considering whether symptoms are returning before the next session can also review how low-dose ketamine treatments may be spaced.

How often should scores be collected?

During an initial treatment series, collecting the primary measure before each session can show the direction of change over time. A clinician-rated scale such as MADRS may be used at selected decision points when staff training and visit time permit. During maintenance, a consistent measure at treatment visits and when the plan changes can preserve a useful record without creating unnecessary burden.

For at-home treatment, a simple symptom and function log can help patients describe the days between sessions. Keep the validated scale’s standard wording and recall period when a score will be compared with published thresholds. If a clinician chooses a shorter recall period for practical monitoring, label it clearly as an adapted check-in rather than treating it as a directly comparable validated score.

Response is not only a lower number. Ask about sleep, work or school tasks, social connection, self-care, and the return of symptoms. For a broader discussion of treatment planning when depression has not improved with prior care, read next steps for treatment-resistant depression.

Interpret trends carefully

A rapid decrease after one treatment can be meaningful, but it does not establish that benefit will persist. Likewise, a modest early change does not by itself establish treatment failure. The useful question is whether repeated measurements show a meaningful direction of change, whether gains hold between sessions, and whether the person is functioning better with acceptable tolerability.

Document the baseline score, raw follow-up scores, percentage change from baseline, dates, treatment number, and the clinical reason for any plan change. This record can make follow-up conversations more specific and can identify patterns that are hard to recall later. Readers who want to understand why response differs between people can review what researchers are studying about biomarkers of ketamine response.

What to discuss with a treating clinician

Bring the same information to each review: which scale is being used, what the baseline score was, how symptoms changed between sessions, whether daily function changed, and whether side effects or safety concerns occurred. Ask what amount of change would prompt a reassessment, what other factors will be considered, and how progress will be documented. This creates a clearer basis for shared decisions than a single good or difficult day.