Patient Screening and Assessment: Identifying Ideal Candidates for Ketamine Therapy

Proper patient selection is paramount to achieving optimal outcomes in ketamine therapy. While ketamine offers remarkable benefits for treatment-resistant conditions, not every patient is an appropriate candidate. This comprehensive guide provides practitioners with systematic approaches to screening, assessment, and medical clearance that maximize therapeutic benefit while ensuring patient safety.

The Importance of Rigorous Screening

Ketamine therapy operates at the intersection of psychiatric treatment and procedural medicine. This dual nature demands comprehensive evaluation that addresses both mental health appropriateness and medical safety. A thorough screening process:

• Identifies patients most likely to benefit
• Excludes those at elevated risk for adverse outcomes
• Establishes baseline parameters for monitoring
• Documents medical necessity for treatment
• Supports informed consent discussions
• Protects both patient and practitioner

Establishing Appropriate Indications

Primary Indications with Strong Evidence

Treatment-Resistant Depression (TRD)

TRD represents the most established indication for ketamine therapy. Operational definitions vary, but generally include:

| Criterion | Definition | |-----------|------------| | Failed trials | ≥2 adequate antidepressant trials | | Adequate trial | Appropriate dose for ≥4-6 weeks | | Current episode | Active moderate-severe depression | | Documented trials | Medical records confirming history |

Clinical Pearl: Ensure "treatment resistance" is genuine by verifying adequate dosing, duration, and adherence to previous trials rather than accepting patient self-report alone.

Acute Suicidal Ideation

Ketamine's rapid-acting antisuicidal properties make it valuable for crisis intervention:

• Active suicidal ideation with intent or plan
• Emergency department presentations
• Bridge therapy during medication initiation
• Severe hopelessness unresponsive to acute interventions

Secondary Indications with Moderate Evidence

Anxiety Disorders

• Generalized anxiety disorder
• Social anxiety disorder
• Treatment-resistant OCD (adjunctive)

PTSD

• Treatment-resistant PTSD
• Often combined with psychotherapy
• May facilitate trauma processing

Chronic Pain Syndromes

• Complex regional pain syndrome (CRPS)
• Fibromyalgia
• Neuropathic pain conditions
• Central sensitization syndromes

Emerging Indications (Limited Evidence)

• Substance use disorders (alcohol, cocaine, opioids)
• Eating disorders
• Bipolar depression (with mood stabilizer)
• Postpartum depression

Inclusion Criteria

Psychiatric Criteria

Required Elements:

1. Confirmed Diagnosis: DSM-5 diagnosis confirmed by structured or semi-structured interview
2. Severity Threshold: Moderate to severe symptomatology
   • PHQ-9 ≥10 (moderate) or ≥15 (moderately severe)
   • MADRS ≥20
   • HAM-D ≥17
3. Treatment History: Documented failure of standard treatments
4. Stability: No acute psychiatric decompensation requiring higher level of care

Favorable Prognostic Indicators:

| Factor | Association with Response | |--------|---------------------------| | Family history of alcohol use disorder | Positive predictor | | BMI > 25 | Some studies show positive correlation | | Anxious depression subtype | May show enhanced response | | Shorter current episode | Better outcomes | | Fewer failed trials | Higher response rate |

Medical Criteria

Baseline Requirements:

• Age 18-65 (standard); 16-75 (expanded with precautions)
• Medically stable without acute conditions
• Adequate hepatic function
• Controlled cardiovascular status
• No active substance intoxication

Absolute Contraindications

Certain conditions represent non-negotiable exclusions due to unacceptable risk:

Psychiatric Contraindications

Active Psychosis

• Current psychotic symptoms (hallucinations, delusions)
• History of ketamine-induced psychosis
• Primary psychotic disorder (schizophrenia, schizoaffective)
• Delusional disorder

Rationale: Ketamine's pro-psychotomimetic effects can exacerbate psychotic symptoms and precipitate prolonged psychotic episodes.

Uncontrolled Mania

• Current manic or hypomanic episode
• Rapid cycling without mood stabilization
• Mixed features with psychotic symptoms

Medical Contraindications

| Condition | Rationale | Considerations | |-----------|-----------|----------------| | Uncontrolled hypertension | Sympathomimetic effects | SBP >180, DBP >100 | | Unstable angina | Cardiovascular stress | Active symptoms | | Recent MI (<3 months) | Cardiac risk | Case-by-case after | | Severe hepatic failure | Impaired metabolism | Child-Pugh C | | Intracranial hypertension | ICP elevation | Active hydrocephalus | | Aneurysmal disease | Hypertensive risk | Unclipped/untreated | | Active pregnancy | Fetal effects | First trimester absolute | | Known ketamine allergy | Anaphylaxis risk | True allergy rare |

Substance-Related Contraindications

Active Substance Intoxication

• Alcohol intoxication
• Stimulant intoxication
• Benzodiazepine intoxication
• Opioid intoxication (relative)

Active Uncontrolled Addiction

• Ketamine use disorder (absolute)
• Active PCP/dissociative use
• Active stimulant use disorder (relative)

Relative Contraindications

Relative contraindications require careful risk-benefit analysis and may be managed with appropriate precautions:

Cardiovascular Considerations

Controlled Hypertension

• Verify BP controlled on current regimen
• Ensure medications taken day of treatment
• More frequent BP monitoring during treatment
• Lower threshold for intervention

Coronary Artery Disease (Stable)

• Cardiology clearance recommended
• Optimize medical management pre-treatment
• Have cardiac emergency protocols ready
• Consider lower doses

Arrhythmias

• Baseline ECG recommended
• Avoid in uncontrolled arrhythmias
• Stable rate-controlled atrial fibrillation acceptable
• Prolonged QT requires specialist input

Psychiatric Considerations

History of Psychosis

• Distinguish primary psychotic disorders (exclude) from secondary/substance-induced (case-by-case)
• Remote history of brief psychotic episode may not be absolute exclusion
• Requires experienced clinician oversight
• Consider lower doses and closer monitoring

Personality Disorders

• Not a contraindication per se
• May affect treatment milieu
• Assess for secondary gain dynamics
• Ensure appropriate support structures

Dissociative Disorders

• Careful assessment of dissociation history
• DID (dissociative identity disorder) requires specialized consideration
• May exacerbate dissociative symptoms
• Trauma-informed approach essential

Active Suicidality Without Safe Discharge

• Ketamine may reduce suicidal ideation but is not standalone treatment
• Requires comprehensive safety planning
• Ensure appropriate level of care available
• May need inpatient setting

Medical Considerations

Hepatic Impairment

• Mild-moderate (Child-Pugh A/B): Proceed with dose reduction
• Severe (Child-Pugh C): Generally avoid
• Monitor for prolonged effects
• Increase observation period

Glaucoma

• Theoretically may increase intraocular pressure
• Limited clinical significance with standard doses
• Ophthalmology clearance for narrow-angle glaucoma
• Open-angle glaucoma not contraindication

Hyperthyroidism

• Uncontrolled: Postpone until treated
• Controlled: Proceed with monitoring
• Risk of hypertensive response enhanced

Mental Health Screening Tools

Depression Assessment

PHQ-9 (Patient Health Questionnaire-9)

• Primary screening tool
• Score interpretation:
  • 0-4: Minimal
  • 5-9: Mild
  • 10-14: Moderate
  • 15-19: Moderately severe
  • 20-27: Severe
• Treatment threshold typically ≥10

MADRS (Montgomery-Asberg Depression Rating Scale)

• Clinician-administered
• More sensitive to change
• Research standard
• Score ≥20 indicates moderate depression

QIDS-SR (Quick Inventory of Depressive Symptomatology)

• Self-report option
• Good correlation with clinician measures
• Useful for tracking

Anxiety Assessment

GAD-7 (Generalized Anxiety Disorder-7)

• Score interpretation:
  • 0-4: Minimal
  • 5-9: Mild
  • 10-14: Moderate
  • 15-21: Severe

STAI (State-Trait Anxiety Inventory)

• Distinguishes state vs. trait anxiety
• Useful for pre-treatment anxiety assessment

Trauma and PTSD

PCL-5 (PTSD Checklist for DSM-5)

• 20-item self-report
• Score ≥31-33 suggests probable PTSD
• Cluster scoring available

Dissociative Experiences Scale (DES)

• Screens for dissociative pathology
• Scores >30 warrant further evaluation
• Important for identifying DID risk

Suicidality Assessment

Columbia Suicide Severity Rating Scale (C-SSRS)

• Gold standard for suicidality screening
• Distinguishes ideation from behavior
• Guides level of care decisions
• Essential for ketamine candidates

Beck Scale for Suicidal Ideation (BSS)

• Validated self-report option
• Useful for tracking changes

Psychosis Screening

PRIME Screen

• Brief prodromal symptom screening
• Identifies at-risk individuals

BPRS (Brief Psychiatric Rating Scale)

• Includes psychotic symptoms
• Clinician-administered

Recommended Screening Battery

| Tool | Purpose | Administration | |------|---------|----------------| | PHQ-9 | Depression severity | Self-report | | GAD-7 | Anxiety severity | Self-report | | C-SSRS | Suicidality risk | Clinician | | DES | Dissociation screening | Self-report | | PRIME Screen | Psychosis risk | Self-report | | Substance use screen | Addiction risk | Mixed |

Medical Clearance Protocols

History and Physical Components

Psychiatric History:

• Current diagnoses and symptoms
• Previous psychiatric treatments (medications, ECT, TMS, therapy)
• Hospitalization history
• Substance use history
• Trauma history
• Family psychiatric history

Medical History:

• Cardiovascular disease
• Hepatic/renal disease
• Neurological conditions
• Respiratory conditions
• Endocrine disorders
• Medication allergies
• Surgical history

Current Medications:

• Complete medication reconciliation
• Identify interacting medications
• Plan for procedural day medications

Social History:

• Living situation and support
• Employment/functional status
• Transportation arrangements
• Caregiver availability post-treatment

Physical Examination

Required Elements:

• Vital signs (BP, HR, RR, SpO2, temperature)
• Weight for dosing calculations
• Cardiovascular examination
• Pulmonary examination
• Neurological screening
• Mental status examination

Targeted Examination Based on History:

• Thyroid examination if endocrine concerns
• Hepatic stigmata if liver disease
• Detailed cardiac exam if cardiovascular history

Laboratory Evaluation

Baseline Labs (Recommended):

| Test | Rationale | Frequency | |------|-----------|-----------| | CBC | Baseline health | Initial | | CMP | Hepatic/renal function | Initial | | TSH | Thyroid status | Initial | | Urine drug screen | Substance use confirmation | Initial + PRN | | Pregnancy test | Contraindication screening | Each treatment (premenopausal) | | Lipid panel | Cardiovascular risk | Baseline | | HbA1c | Metabolic status | If diabetic/at risk |

Additional Labs Based on Indication:

• ECG if cardiovascular risk factors
• LFTs if hepatic concerns
• Coagulation studies if bleeding risk

Specialist Consultations

When to Obtain:

| Situation | Consultation | |-----------|--------------| | Cardiovascular disease | Cardiology clearance | | Significant hepatic disease | Hepatology/GI | | Neurological conditions | Neurology | | Primary psychotic history | Psychiatry (if not treating) | | Complex medical comorbidity | Primary care/internal medicine | | Pregnancy consideration | Obstetrics |

Documentation Requirements

Pre-Treatment Documentation Checklist:

• [ ] Psychiatric evaluation with confirmed diagnosis
• [ ] Treatment history documenting resistance criteria
• [ ] Medical history and physical examination
• [ ] Review of systems
• [ ] Allergy documentation
• [ ] Current medication list
• [ ] Baseline screening instruments (PHQ-9, GAD-7, C-SSRS)
• [ ] Laboratory results
• [ ] Contraindication assessment
• [ ] Risk-benefit analysis documented
• [ ] Informed consent signed
• [ ] Transportation/safety plan confirmed

Creating a Comprehensive Intake Process

Initial Phone Screening

Before scheduling comprehensive evaluation:

Key Screening Questions:

1. What brings you to seek ketamine treatment?
2. What is your psychiatric diagnosis?
3. What treatments have you tried?
4. Do you have any history of psychosis or schizophrenia?
5. Do you have any significant heart conditions?
6. Are you currently pregnant or planning pregnancy?
7. Do you use any recreational drugs, including ketamine?
8. Can you arrange safe transportation after treatment?

Red Flags Requiring Immediate Attention:

• Current psychotic symptoms
• Active suicidal crisis
• Recent cardiac event
• Current pregnancy
• Active ketamine/PCP use

In-Person Evaluation

First Visit Components:

1. Comprehensive psychiatric evaluation (60-90 minutes)

   • Diagnostic interview
   • Treatment history
   • Risk assessment

2. Medical evaluation (30-45 minutes)

   • History and physical
   • Contraindication review

3. Screening instruments

   • Self-report completion
   • Clinician-administered tools

4. Education and informed consent

   • Treatment explanation
   • Risk/benefit discussion
   • Consent documentation

5. Treatment planning

   • Protocol selection
   • Scheduling
   • Preparation instructions

Pre-Treatment Confirmation

Day Before Treatment:

• Confirm appointment
• Review NPO instructions (if applicable)
• Verify transportation arrangements
• Confirm medication instructions
• Address questions/concerns

Day of Treatment:

• Repeat vital signs
• Confirm no contraindication changes
• Verify transportation present
• Pregnancy test (premenopausal women)
• Urine drug screen (if indicated)
• Brief mental status assessment
• Review safety plan

Special Population Considerations

Geriatric Patients

Additional Considerations:

• Comprehensive cognitive assessment (MoCA or similar)
• Falls risk evaluation
• Polypharmacy review
• Caregiver involvement
• Extended monitoring period
• Reduced initial dosing

Adolescents

Requirements:

• Parental consent and patient assent
• Careful psychosis risk screening
• Substance use assessment
• School/family involvement
• Specialist psychiatric oversight
• Limited evidence acknowledgment

Patients with Substance Use History

Assessment Priorities:

• Detailed substance use history
• Current recovery status
• Relapse risk factors
• Addiction medicine consultation
• Abuse potential discussion
• Enhanced monitoring protocols

Clinical Takeaways

1. Systematic Screening Saves Lives: A comprehensive, standardized screening protocol identifies high-risk patients before treatment, preventing adverse outcomes and ensuring appropriate candidate selection.

2. Absolute Contraindications Are Non-Negotiable: Active psychosis, uncontrolled hypertension, and known ketamine allergy represent firm exclusions. Do not rationalize exceptions.

3. Relative Contraindications Require Documentation: When proceeding with relative contraindications, document the risk-benefit analysis, precautions taken, and informed consent discussion.

4. Validate Treatment Resistance: Confirm that "treatment-resistant depression" meets operational criteria through medical record review, not patient report alone. Ensure adequate dosing, duration, and adherence of previous trials.

5. Standardize Your Process: Develop intake protocols, screening batteries, and documentation templates. Consistency improves safety and supports defensible practice.

6. Screen for Dissociation and Psychosis Risk: These conditions require specialized assessment. The DES and PRIME Screen are brief but important additions to standard depression/anxiety measures.

7. Medical Clearance Is Medical Necessity: Document baseline health status and address cardiovascular, hepatic, and other medical factors systematically. Specialist consultation demonstrates appropriate caution.

8. Plan for the Worst: Even well-screened patients can have unexpected responses. Have emergency protocols, reversal agents, and escalation pathways ready before beginning treatment.

This screening protocol represents current best practices but should be adapted to individual clinical settings and patient populations. Local regulations, payer requirements, and institutional policies may necessitate modifications. Regular protocol review and updates ensure continued alignment with evolving evidence.

References

1. Sanacora G, et al. A Consensus Statement on the Use of Ketamine in the Treatment of Mood Disorders. JAMA Psychiatry. 2017;74(4):399-405.
2. McIntyre RS, et al. Synthesizing the Evidence for Ketamine and Esketamine in Treatment-Resistant Depression. Am J Psychiatry. 2021;178(5):383-399.
3. Krystal JH, et al. Ketamine: A Paradigm Shift for Depression Research and Treatment. Neuron. 2019;101(5):774-778.
4. Wilkinson ST, et al. Identifying Predictors of Response to Ketamine. J Clin Psychiatry. 2017;78(9):e1218-e1219.
5. American Psychiatric Association. Practice Guideline for the Treatment of Patients with Major Depressive Disorder. 2010.