Source / episode info

• **Episode:**633
• **Title:**DIP Ep 633: USMLE Step 2/3 Rapid Review Series 132
• **Published:**2026-02-16
• Source:Episode page

One-liner

This episode provides a rapid review covering levels of prevention, common presentations of telogen effluvium, the clinical triad of anterior uveitis, HIV associated neurocognitive disorder, biostatistical study design pitfalls (confounding/stratification), and high-yield pharmacology mechanisms for drugs like amlodipine and propranolol.

High-yield summary

• Levels of Prevention: Primary prevention aims to prevent disease development (e.g., wearing N95 masks); Secondary prevention involves screening to detect early disease (e.g., audiometry in a hearing conservation program); Tertiary prevention focuses on minimizing disability/preventing worsening once pathology is established (e.g., fit-testing earplugs for mild hearing loss).
• Telogen Effluvium: This common cause of diffuse, acute hair thinning occurs following major physiological stressors such as rapid weight loss, severe illness (MI), surgery, or pregnancy. Prognosis is typically excellent and self-limited.
• HIV Associated Neurocognitive Disorder (HAND): The most critical risk factor for HAND is a low CD4 count (<200 cells/mm³). Clinicians must differentiate HAND from Alzheimer's disease; the presence of oral candidiasis suggests an immunocompromised state.
• Anterior Uveitis (AIV): While often idiopathic, AIV can be associated with systemic diseases like IBD or seronegative spondyloarthropathies. The most common etiology tested on exams is idiopathic.
• Biostatistics: Cross-sectional studies only provide prevalence information (a snapshot in time); they cannot determine incidence. Stratification to control for confounding must occur during the analysis phase, while randomization occurs during the selection phase.
• Pharmacology Integration: Drugs like amlodipine (dihydropyridine CCB) cause peripheral edema by dilating arterioles, increasing capillary hydrostatic pressure; this effect can be counteracted by ACE inhibitors which dilate post-capillary venules.

Learning objectives

• Differentiate between primary, secondary, and tertiary levels of prevention using clinical scenarios.
• Recognize the key risk factors and differential diagnoses associated with anterior uveitis (AIV).
• Interpret biostatistical study designs to correctly determine whether prevalence or incidence can be measured.
• Identify the most critical prognostic factor for HIV Associated Neurocognitive Disorder (HAND).
• Correlate drug mechanisms of action (e.g., CCBs, alpha-blockers) with common side effects and necessary countermeasures.