Residency · Residency · Medicine Pediatrics
Asthma Across the Lifespan
Overview
Asthma is the most common chronic disease of childhood and remains highly prevalent in adults. Pediatric asthma phenotypes (viral-induced wheeze, atopic asthma) differ from adult-onset asthma and asthma-COPD overlap. The Med-Peds physician must navigate different classification systems, stepwise therapy guidelines, and the expanding role of biologics while managing the unique challenges of adolescent asthma adherence.
Epidemiology
Pediatric prevalence: approximately 8% of US children; higher in Black and Puerto Rican children. Adult prevalence: approximately 8% of US adults. Childhood asthma is more common in boys; adult asthma is more common in women. Asthma is the leading cause of school absenteeism from chronic disease. Significant health disparities: Black children have 2x the prevalence, 4x the ED visit rate, and 8x the mortality rate compared to White children.
Asthma Phenotypes Across Ages
Pediatric Phenotypes
Viral-induced wheeze (transient early wheeze): most common in preschool children; triggered by viral URI (RSV, rhinovirus); often resolves by age 6; does not necessarily lead to persistent asthma. Atopic asthma: begins in early childhood; associated with eczema, food allergy, allergic rhinitis (atopic march); elevated IgE, eosinophilia, positive skin prick testing; likely to persist into adulthood. Exercise-induced bronchospasm: common in school-age children and adolescents; may be the only manifestation. Severe asthma: approximately 5% of pediatric asthma; often T2-high with eosinophilic inflammation; candidates for biologics.
Adult Phenotypes
Allergic (T2-high) asthma: continuation of childhood atopic asthma; eosinophilic, elevated FeNO, responds to ICS and biologics. Non-allergic (T2-low) asthma: adult-onset, often female, non-atopic, neutrophilic or paucigranulocytic; less responsive to ICS. Adult-onset eosinophilic asthma: late onset (>40), severe, often with nasal polyps and aspirin sensitivity (AERD/Samter triad) Obesity-related asthma: non-T2, mechanistic link through adipokines, airway compression, and systemic inflammation. Asthma-COPD overlap (ACO): features of both asthma and COPD; typically in patients >40 with smoking history and persistent airflow limitation plus reversibility; managed with ICS-containing regimens (never LAMA alone)
Diagnosis
Pediatric Diagnosis
In children <5: diagnosis is clinical; based on pattern of symptoms, response to bronchodilators, and exclusion of alternatives. Modified Asthma Predictive Index (mAPI): helps predict persistence of asthma in preschool wheezers. Positive mAPI: >=3 wheezing episodes/year PLUS 1 major criterion (parental asthma, eczema, aeroallergen sensitization) OR 2 minor criteria (food allergy, >=4% eosinophilia, wheeze without URI) In children >=5: spirometry with reversibility testing (>=12% and >=200 mL increase in FEV1 post-bronchodilator) Challenge testing: methacholine or exercise challenge if baseline spirometry is normal but clinical suspicion is high.
Adult Diagnosis
Spirometry: FEV1/FVC <0.70 with >=12% and >=200 mL reversibility post-bronchodilator. FeNO: >=25 ppb supports T2/eosinophilic inflammation (>=50 ppb highly suggestive) Methacholine challenge: PC20 <4 mg/mL diagnostic; useful when spirometry is normal. Peak flow variability: >20% diurnal variation supports diagnosis. Blood eosinophils: >=300 cells/mcL suggests T2-high phenotype; predicts biologic responsiveness.
Classification of Severity
NAEPP/EPR-3 Classification (Pediatric and Adult)
Intermittent: symptoms <=2 days/week, nighttime awakenings <=2x/month, SABA use <=2 days/week, no interference with activity, FEV1 >80%. Mild persistent: symptoms >2 days/week (not daily), nighttime 3-4x/month, minor limitation, FEV1 >=80%. Moderate persistent: daily symptoms, nighttime >1x/week, some limitation, FEV1 60-80%. Severe persistent: symptoms throughout the day, nighttime nightly, extreme limitation, FEV1 <60%.
Assessing Control (Ongoing)
ACT (Asthma Control Test): validated for ages >=12; score >=20 = well controlled. c-ACT (Childhood ACT): for ages 4-11. GINA assessment: symptom control (well controlled, partly controlled, uncontrolled) + risk factors for exacerbation.
Stepwise Therapy
GINA 2023 Updates (Adults and Adolescents >=12)
Track 1 (Preferred): ICS-formoterol as both maintenance and reliever (MART strategy) Step 1: as-needed low-dose ICS-formoterol. Step 2: low-dose ICS-formoterol maintenance + as-needed. Step 3: medium-dose ICS-formoterol maintenance + as-needed. Step 4: add-on LAMA (tiotropium); refer for phenotyping. Step 5: add-on biologic (based on phenotype); refer to specialist. Track 2 (Alternative): ICS-LABA with SABA reliever. Key change: GINA no longer recommends SABA-only treatment at any step; all patients should receive ICS (even if as-needed)
Pediatric Stepwise (NAEPP/EPR-4 2020 Focused Updates + GINA)
Ages 0-4: Step 1: as-needed SABA; Step 2: low-dose ICS daily; Step 3: medium-dose ICS; Step 4: medium-dose ICS + LABA or montelukast; referral; Ages 5-11: Step 1: as-needed SABA (GINA prefers as-needed ICS-SABA); Step 2: low-dose ICS daily; Step 3: low-dose ICS-LABA OR medium-dose ICS; Step 4: medium-dose ICS-LABA; Step 5: high-dose ICS-LABA; consider biologic, oral steroids; Ages >=12: follow adult GINA guidelines.
Key Medications
ICS: budesonide, fluticasone propionate, mometasone, beclomethasone. Growth suppression: small effect (~0.5-1 cm reduction in final adult height with low-dose ICS); benefits outweigh risks. LABA: formoterol (fast-onset, used in MART), salmeterol; NEVER use LABA alone without ICS (FDA black box, SMART trial) LTRA: montelukast; FDA black box warning for neuropsychiatric events (2020); use only if benefits outweigh risks. LAMA: tiotropium; add-on at Step 4-5; approved for ages >=6. SABA: albuterol (salbutamol); rescue therapy; overuse (>2 canisters/year) indicates poor control. Systemic corticosteroids: prednisone/prednisolone burst for exacerbations (1-2 mg/kg/day in children, 40-60 mg/day in adults, 3-5 days)
Biologic Therapies
Indications
Severe persistent asthma uncontrolled on Step 4-5 therapy. Phenotype-guided selection based on biomarkers (eosinophils, IgE, FeNO)
Available Biologics
| Agent | Target | Biomarker Criteria | Pediatric Age Approval |
|---|---|---|---|
| Omalizumab | Anti-IgE | Elevated IgE + aeroallergen sensitization | >=6 years |
| Mepolizumab | Anti-IL-5 | Eosinophils >=150 | >=6 years |
| Benralizumab | Anti-IL-5R | Eosinophils >=300 | >=12 years |
| Dupilumab | Anti-IL-4Ra | Eosinophils >=150 or FeNO >=25 | >=6 years |
| Tezepelumab | Anti-TSLP | Broad (T2-high and T2-low) | >=12 years |
Impact of Biologics
50-70% reduction in exacerbations; Oral corticosteroid sparing; Improved lung function and quality of life; Whether early biologic use in children alters disease natural history remains an open question.
Acute Asthma Exacerbation Management
Pediatric ED Management
Albuterol nebulization: 2.5-5 mg q20min x 3 doses, then q1-4h; or continuous nebulization (10-20 mg/hr) for severe. Ipratropium bromide: 0.25-0.5 mg nebulized q20min x 3 doses (first hour only, for moderate-severe) Systemic corticosteroids: dexamethasone 0.6 mg/kg (max 16 mg) x 1-2 doses increasingly preferred over 5-day prednisone burst (equivalent efficacy, better adherence) Magnesium sulfate: 25-75 mg/kg IV (max 2 g) for severe exacerbation not responding to initial therapy. IV terbutaline: for impending respiratory failure. Heliox: 70:30 or 80:20 helium-oxygen mixture to reduce airway resistance (limited evidence)
Adult ED Management
Albuterol MDI (4-8 puffs q20min) or nebulization (2.5-5 mg q20min) Ipratropium 0.5 mg nebulized q20min x 3 doses. Systemic corticosteroids: prednisone 40-60 mg PO or methylprednisolone 125 mg IV. Magnesium sulfate: 2 g IV over 20 minutes for severe exacerbation. BiPAP for impending respiratory failure. Intubation: ketamine as induction agent (bronchodilator properties); low respiratory rate, prolonged expiratory time on ventilator settings.
Asthma in Adolescents: Unique Challenges
Adherence is lowest in the adolescent age group. Common barriers: denial of disease, peer pressure, forgetfulness, steroid fears. Transition from parent-managed to self-managed care. Vaping and marijuana use exacerbate asthma. Exercise-related symptoms may limit sports participation (but exercise should be encouraged with proper pretreatment) Confidential assessment of adherence, substance use, and psychosocial factors.
<image>A stepwise therapy diagram comparing GINA 2023 adult/adolescent recommendations (Track 1 with ICS-formoterol MART approach at each step) with the pediatric stepwise approach for ages 0-4 and 5-11. Each step shows the preferred controller and reliever medications, with connecting arrows indicating step-up and step-down decisions based on symptom control and exacerbation risk. Biologic therapy options are displayed at Steps 4-5 with biomarker-based selection criteria shown in a decision box.</image>
<image>A phenotype classification wheel for asthma across the lifespan. The wheel is divided into segments representing different phenotypes: viral-induced wheeze (preschool, shown resolving by age 6), atopic/T2-high asthma (childhood through adulthood, largest segment), adult-onset eosinophilic asthma (late onset with nasal polyps), obesity-related asthma (T2-low), and asthma-COPD overlap (older adults). Each segment shows characteristic biomarkers (IgE, eosinophils, FeNO, neutrophils), typical patient demographics, and preferred treatment approach including specific biologic targets.</image>
<image>An acute asthma exacerbation management flowchart comparing pediatric and adult protocols side by side. Both start with severity assessment (mild/moderate/severe/life-threatening), then show parallel treatment pathways with age-appropriate dosing for albuterol, ipratropium, systemic steroids (highlighting dexamethasone single-dose option in pediatrics), and magnesium sulfate. Disposition decision points show PEF/FEV1 thresholds for discharge versus admission. Red flags for intubation are listed at the bottom with age-specific ventilator considerations.</image>
Clinical Pearls
GINA no longer recommends SABA-only treatment at any step -- even mild intermittent asthma should include ICS (at least as-needed ICS-formoterol) The SMART trial showed LABA monotherapy increased asthma deaths -- NEVER prescribe a LABA without an ICS. Montelukast carries an FDA black box warning for neuropsychiatric events (mood changes, suicidality) -- discuss risks and benefits, especially in children. Dexamethasone 0.6 mg/kg x 1-2 doses is increasingly replacing 5-day prednisone bursts for pediatric asthma exacerbations with equivalent efficacy and better adherence. Low-dose ICS causes approximately 0.5-1 cm reduction in final adult height -- this is clinically insignificant compared to the benefits of asthma control. Albuterol overuse (>2 canisters/year) is a marker of uncontrolled asthma and increased exacerbation risk -- not a solution. In adolescents, always ask about vaping and marijuana use as triggers for asthma exacerbation. Biologic selection should be guided by phenotype and biomarkers -- there is no one-size-fits-all approach.
References
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2023 Update.
- Expert Panel Working Group. 2020 Focused Updates to the Asthma Management Guidelines. J Allergy Clin Immunol. 2020;146(6):1217-1270.
- Castro M, Corren J, Pavord ID, et al. Dupilumab efficacy and safety in moderate-to-severe uncontrolled asthma. N Engl J Med. 2018;378(26):2486-2496.
- Chipps BE, Lanier B, Milgrom H, et al. Omalizumab in children with uncontrolled allergic asthma. J Allergy Clin Immunol. 2017;139(5):1431-1439.
- Kelly HW, Sternberg AL, Lescher R, et al. Effect of inhaled glucocorticoids in childhood on adult height. N Engl J Med. 2012;367(10):904-912.
- Keeney GE, Gray MP, Morrison AK, et al. Dexamethasone for acute asthma exacerbations in children: a meta-analysis. Pediatrics. 2014;133(3):493-499.
