What ICD‑10 code should I assign for a patient with a Patient Health Questionnaire‑9 (PHQ‑9) score of 10 indicating moderate depression, and what first‑line treatment is recommended?

PHQ-9 Score of 10: ICD-10 Coding and First-Line Treatment

A PHQ-9 score of 10 indicates moderate depression and should be coded as F32.1 (Major depressive disorder, single episode, moderate) or F33.1 (Major depressive disorder, recurrent, moderate), depending on episode history, and first-line treatment consists of either an SSRI (such as sertraline 50 mg daily) or individually guided self-help based on cognitive behavioral therapy with behavioral activation. 1, 2, 3

Immediate Safety Assessment

• Always assess PHQ-9 item 9 (self-harm thoughts) first, regardless of the total score of 10, as any endorsement of suicidal ideation mandates immediate emergency psychiatric evaluation even when the total score suggests only moderate depression 1, 2, 3
• If item 9 is endorsed at any frequency, arrange one-to-one observation and remove access to lethal means while awaiting emergency psychiatric evaluation 3

ICD-10 Coding Algorithm

For a PHQ-9 score of 10:

• Use F32.1 (Major depressive disorder, single episode, moderate) if this is the patient's first depressive episode 4, 5
• Use F33.1 (Major depressive disorder, recurrent, moderate) if the patient has a history of prior depressive episodes 4, 5
• A score of 10 falls within the 8-14 range, which represents moderate depressive symptomatology with mild-to-moderate functional impairment 1, 2

Diagnostic Workup Before Treatment

• Check thyroid-stimulating hormone, complete metabolic panel, complete blood count, vitamin B12, and folate to rule out medical causes of depression 3
• Review current medications for mood-altering side effects, particularly interferon, corticosteroids, and beta-blockers 3
• Assess for substance-induced causes of depressive symptoms 6

First-Line Treatment Options

For PHQ-9 scores 8-14 (moderate depression), you have two evidence-based first-line options:

Option 1: Low-Intensity Psychological Intervention

• Initiate individually guided self-help based on cognitive behavioral therapy (CBT) with behavioral activation and problem-solving components 2, 3
• Include structured physical activity programs as part of the treatment plan 3

Option 2: Pharmacologic Treatment

• Start an SSRI such as sertraline 50 mg daily, escitalopram 10 mg daily, or fluoxetine 20 mg daily 3
• SSRIs are preferred over other antidepressants due to their favorable side-effect profile and extensive evidence base 3

When to Escalate Care

• Refer to psychology or psychiatry for diagnostic confirmation when PHQ-9 scores fall in the 8-14 range, as formal diagnostic assessment is recommended to confirm the presence or absence of a mood disorder 6, 1
• If the score progresses to ≥15 on repeat screening, immediate referral to psychology and/or psychiatry becomes mandatory for high-intensity interventions 1, 2

Monitoring and Follow-Up

• Reassess with PHQ-9 at regular intervals during treatment (typically every 2-4 weeks initially) to monitor treatment response 3
• Continue monitoring at 3,6, and 12 months, or during times of personal transition, family crisis, or changes in health status 1, 3

Common Pitfalls to Avoid

• Never omit assessment of item 9, as patients can have moderate total scores but still endorse suicidal ideation requiring immediate intervention 1, 2, 3
• Do not delay treatment while waiting for specialty referral; initiate first-line treatment (either low-intensity CBT or SSRI) while arranging consultation 2, 3
• Avoid using the PHQ-9 algorithm scoring method for screening purposes, as it has lower sensitivity compared to the summed-item score method; the summed score at cutoff ≥10 has better diagnostic performance 7
• In elderly patients or those with cognitive impairment, consider alternative assessment tools, as the PHQ-9 loses accuracy in these populations 2, 3