What is the diagnostic approach and treatment for a patient with suspected illness anxiety disorder?

Illness Anxiety Disorder: Diagnosis and Treatment

Illness anxiety disorder is diagnosed when a patient exhibits excessive, uncontrollable worry specifically about having or developing a serious illness (not general life worries), with the core pathology being a cycle of health-related worry and reassurance-seeking behavior rather than distress from actual somatic symptoms. 1

Diagnostic Criteria and Differentiation

The critical distinction is that illness anxiety disorder focuses on anxiety about illness itself, whereas somatic symptom disorder centers on distress from physical symptoms. 1 This differentiation is essential for proper diagnosis and treatment planning.

Core Diagnostic Features to Assess:

• Preoccupation with having or acquiring a serious illness despite minimal or no somatic symptoms 1
• High level of anxiety about health that is disproportionate to any actual medical findings 1
• Excessive health-related behaviors (repeatedly checking body for signs of illness, frequent doctor visits) or maladaptive avoidance (avoiding medical care, avoiding hearing about disease) 1
• Duration of at least 6 months (though the specific illness feared may change) 1
• Significant functional impairment in social, occupational, or other important areas 2

Essential Medical Differential Diagnosis

Before diagnosing illness anxiety disorder, you must systematically rule out actual medical conditions that can cause or mimic anxiety symptoms: 3, 2

• Thyroid disorders (hyperthyroidism is a common masquerader—order TSH and free T4) 3, 4
• Cardiac conditions (arrhythmias, valvular disease, coronary artery disease) 3, 4
• Endocrine disorders (hypoglycemia, pheochromocytoma, diabetes) 3
• Respiratory conditions (asthma, hypoxia) 3, 2
• Neurological disorders (CNS disorders, migraine) 3
• Substance-related causes (caffeinism, medication side effects, substance withdrawal) 3, 2

Laboratory testing is not routine but should be ordered when clinical signs suggest a medical condition—specifically glucose and thyroid function tests are most commonly indicated. 3

Psychiatric Comorbidities to Screen

Illness anxiety disorder commonly co-occurs with other psychiatric conditions that must be identified and may require separate treatment: 3

• Depression (most common comorbidity) 3, 2
• Other anxiety disorders (generalized anxiety disorder, panic disorder, social anxiety) 3
• Obsessive-compulsive disorder (can have overlapping features with health-related obsessions) 2
• Substance use disorders 2

Use standardized screening tools like the GAD-7 to quantify anxiety severity and the Level 1 Cross-Cutting Symptom Measures to efficiently screen for comorbidities. 3, 4

Structured Assessment Approach

Conduct a comprehensive diagnostic interview that includes: 3

• Patient interview using developmentally appropriate techniques 3
• Collateral information from family members, primary care providers, and medical records 3
• Mental status examination observing for signs of anxiety (hypervigilance, restlessness, trembling, poor eye contact) 2, 5
• Functional impairment assessment across occupational, social, and self-care domains 2

While structured interview guides like the Anxiety Disorders Interview Schedule (ADIS) enhance diagnostic accuracy, they are time-intensive; alternatively, use the K-SADS-PL DSM-5 interview guide which is freely available and includes screening for comorbidities. 3

Safety Assessment

Always evaluate for immediate safety concerns: 2, 5

• Suicidal ideation or self-harm behaviors 2, 5
• Risk of harm to others 4, 2
• Severe functional impairment requiring immediate intervention 4

Treatment Approach

First-Line Treatment

Cognitive Behavioral Therapy (CBT) is the first-line psychotherapy for illness anxiety disorder, with demonstrated large effect sizes (Hedges g = 1.01) for anxiety disorders. 4, 6, 1 CBT specifically targets the maladaptive thought patterns and reassurance-seeking behaviors that maintain the disorder. 1

For pharmacotherapy, selective serotonin reuptake inhibitors (SSRIs) are first-line, with sertraline being a preferred agent. 4, 6, 7 SSRIs show small to medium effect sizes compared to placebo (SMD -0.55 for generalized anxiety) but are effective for health anxiety. 6

Treatment Algorithm

For mild symptoms (GAD-7 score <10): 4

• Initiate CBT alone 4, 1
• Provide psychoeducation about the disorder 6, 1
• Monitor response over 4-6 weeks 7

For moderate-severe symptoms (GAD-7 score ≥10): 4

• Combine SSRI with CBT—this combination is superior to either treatment alone 4
• Start sertraline or another SSRI at standard dosing 4, 6
• Refer to psychology/psychiatry for structured CBT 4

Avoid benzodiazepines for routine treatment due to abuse potential and adverse effects, despite their short-term efficacy. 7, 8

Duration of Treatment

Continue pharmacotherapy for 12 months after achieving remission before considering tapering to prevent relapse. 7, 8 This extended maintenance phase is critical as anxiety disorders tend to be chronic. 6

When to Refer Immediately

Immediate psychiatric referral is required for: 4, 2

• Suicidal ideation or self-harm 4, 2
• Psychosis or severe agitation 4
• Symptoms not responding to initial treatment 4
• Severe functional impairment 4

Critical Clinical Pitfalls

The most important pitfall to avoid is excessive medical testing and procedures driven by the patient's reassurance-seeking behavior. 1 This creates a harmful cycle where testing temporarily reduces anxiety but ultimately reinforces the illness preoccupation. Collaboration between medical providers is essential to establish consistent boundaries around testing and avoid unnecessary interventions. 1

Maintain an empathic, curious, and nonjudgmental stance toward the patient's health anxiety rather than dismissing concerns, as this fosters the therapeutic alliance necessary for successful treatment. 1