What is the expected basic level of evaluation, ICD-10 (International Classification of Diseases, 10th Revision) code, and billing procedure for a primary care physician evaluating patients with psychiatric concerns, specifically mild to moderate depression or anxiety?

Basic Psychiatric Evaluation in Primary Care

As a primary care physician handling psychiatric referrals, you should screen using validated tools (PHQ-9 for depression, GAD-7 for anxiety), assess for suicidal ideation and medical causes, and use ICD-10 codes F32.x-F33.x for depression or F41.x for anxiety disorders, billing under standard E/M codes (99213-99215) based on time and complexity. 1, 2

Required Initial Screening Tools

• Use PHQ-9 as your primary depression screening tool, with scores ≥10 indicating moderate to severe depression requiring further assessment 2
• Use GAD-7 for anxiety screening, with the following interpretation: scores 5-9 indicate mild anxiety, 10-14 moderate anxiety, and 15-21 severe anxiety requiring mental health referral 3, 2
• For ultra-brief screening, use GAD-2 (first two questions of GAD-7), with a score ≥3 warranting full GAD-7 administration 3

Critical Safety Assessment (Must Be Done First)

• Directly ask about suicidal ideation using specific language: "Have you ever wished you were dead?" and "Have you ever done anything on purpose to hurt or kill yourself?" 1
• If positive responses, immediately assess for a specific plan and access to firearms, and refer for emergency psychiatric evaluation if any self-harm risk is identified 1
• Assess for risk of harm to others, severe agitation, psychosis, or confusion (delirium)—these require immediate psychiatric referral 3

Rule Out Medical Causes Before Psychiatric Diagnosis

This is a critical step that prevents misdiagnosis and improves outcomes. 2, 4

• Order TSH on all patients presenting with anxiety or depression, as thyroid dysfunction commonly mimics psychiatric illness 2, 4
• Check for anemia, vitamin deficiencies (especially B12, folate), and review all current medications for side effects that cause depression or anxiety 1, 2
• Screen for substance abuse, as this commonly co-occurs with anxiety and depression 2
• Assess for unrelieved pain, fatigue, infection, or electrolyte imbalances that can present as psychiatric symptoms 2

ICD-10 Coding for Common Presentations

For Depression: 1

• F32.0 - Mild depressive episode
• F32.1 - Moderate depressive episode
• F32.2 - Severe depressive episode without psychotic features
• F33.x - Recurrent depressive disorder (if prior episodes)

For Anxiety: 3

• F41.1 - Generalized anxiety disorder
• F41.0 - Panic disorder
• F40.10 - Social anxiety disorder (social phobia)

Billing and Documentation

• Bill using standard E/M codes (99213-99215) based on time spent and medical decision-making complexity 3
• Document the validated screening tool scores (PHQ-9, GAD-7) in the medical record 3, 2
• Document functional impairment in work, relationships, and daily activities—this is essential for justifying the diagnosis and treatment 1
• Time-based billing is appropriate when more than 50% of the visit involves counseling or coordination of care 3

When to Refer vs. Manage

Manage in primary care if: 3

• Mild to moderate depression (PHQ-9 10-19) or anxiety (GAD-7 5-14) without suicidal ideation
• No psychotic symptoms, severe agitation, or substance abuse requiring detoxification
• Patient has adequate social support and can follow up reliably

Immediate psychiatric referral required for: 3, 1

• Active suicidal ideation with plan or intent
• Psychotic symptoms (hallucinations, delusions)
• Severe depression (PHQ-9 ≥20) or severe anxiety (GAD-7 ≥15)
• Bipolar disorder or other complex psychiatric conditions
• Failure to respond to initial treatment after 6-8 weeks

Initial Management for Mild-Moderate Cases

For depression: 1

• Start SSRI as first-line medication (fluoxetine, sertraline, escitalopram)
• Refer for cognitive-behavioral therapy (CBT) or psychoeducational therapy
• Reassess at 6-8 weeks using PHQ-9 to document response

For anxiety: 3

• Consider SSRI for generalized anxiety disorder
• Refer for CBT targeting worry and avoidance behaviors
• Reassess at 6-8 weeks using GAD-7

Common Pitfalls to Avoid

• Do not skip the suicidal ideation assessment, even in patients who appear low-risk 1
• Do not diagnose psychiatric illness without checking TSH first—thyroid dysfunction can fully explain depression and anxiety symptoms 2, 4
• Do not dismiss irritability as "just stress" in young adults—this is often how depression presents in this age group 1
• Do not rely on symptom counts alone—always assess functional impairment and duration of symptoms 1
• Do not exclude patients with comorbid depression and anxiety—most real-world patients have both conditions 3

Establishing Your Practice System

• Train office staff to administer PHQ-9 and GAD-7 before the visit, similar to vital signs 3
• Establish linkages with local mental health resources for referrals when needed 3
• Create an emergency communication plan for patients to contact you if symptoms worsen between visits 3
• Use electronic medical records to track screening scores and treatment response over time 3