A 28-year-old woman with asthma presents with persistent dyspnea despite inhaled salbutamol. Spirometry shows FEV₁ 65% predicted, FVC 80% predicted, and FEV₁/FVC ratio 0.81. Post-bronchodilator FEV₁ improves to 78% predicted. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient has asthma with: - **Spirometric pattern:** FEV₁/FVC 0.81 (normal; > 0.70), FEV₁ 65% predicted (mild reduction) - **Bronchodilator response:** FEV₁ improves from 65% to 78% (13% absolute improvement, ~20% relative improvement) — **diagnostic of reversible airway obstruction** - **Clinical presentation:** Persistent symptoms despite SABA use ## Next Step Rationale **Key Point:** A patient with asthma, reversible airway obstruction on spirometry, and persistent symptoms on SABA alone requires **step-up to regular controller therapy**. ICS monotherapy is the first-line controller agent for mild-to-moderate asthma. **High-Yield:** GINA guidelines recommend ICS as the foundation of asthma control. For mild asthma (FEV₁ 60–80% predicted, infrequent symptoms), ICS monotherapy is appropriate. ICS/LABA combination is reserved for inadequate control on ICS alone or moderate-to-severe asthma. **Clinical Pearl:** The 13% absolute improvement in FEV₁ post-bronchodilator (65% → 78%) exceeds the threshold for clinically significant reversibility (typically ≥12% and ≥200 mL). This confirms asthma diagnosis and guides controller selection. **Mnemonic: GINA Step-Up** — **G**ood control on SABA alone → add ICS; **I**nadequate control on ICS → add LABA; **N**eed high-dose ICS/LABA → consider LTRA or LAMA; **A**dvanced/severe → triple therapy or biologics. ## Why Other Options Are Not Next Steps | Option | Rationale for Rejection | | --- | --- | | Methacholine challenge | Asthma is already confirmed by reversible airway obstruction on spirometry. Methacholine challenge is useful when asthma is suspected but spirometry is normal; it is not needed here and delays initiation of therapy. | | ICS/LABA combination | Combination therapy is indicated for inadequate control on ICS monotherapy or moderate-to-severe asthma. This patient has mild asthma; ICS monotherapy is first-line. Jumping to combination therapy is over-treatment. | | Chest X-ray | No clinical features suggesting alternative diagnosis (fever, focal findings, hemoptysis). CXR is not indicated in uncomplicated asthma and delays initiation of controller therapy. | ## Management Algorithm ```mermaid flowchart TD A[Asthma diagnosis confirmed]:::outcome --> B[Assess severity & control]:::decision B -->|Mild, well-controlled| C[SABA PRN only]:::action B -->|Mild-moderate, persistent symptoms| D[Initiate ICS monotherapy]:::action B -->|Moderate-severe or inadequate ICS control| E[ICS/LABA combination]:::action D --> F[Review in 4 weeks]:::action F --> G{Control achieved?}:::decision G -->|Yes| H[Continue ICS, monitor]:::outcome G -->|No| I[Step up to ICS/LABA]:::action ``` [cite:GINA 2023 Report; Harrison 21e Ch 299]