How can asthma scoring systems help reduce mortality in patients with asthma?

Asthma Scoring Systems and Mortality Reduction

Asthma scoring systems reduce mortality by enabling objective severity assessment that prevents the fatal underestimation of attack severity—a primary cause of preventable asthma deaths—and by triggering specific, escalating treatment protocols based on measurable thresholds. 1

Why Objective Scoring Prevents Deaths

The failure to objectively measure severity is a leading factor in preventable asthma mortality. 1 Patients, relatives, and physicians commonly underestimate attack severity when relying on subjective assessment alone. 1 Objective measurements must be obtained in every emergency consultation until proven otherwise that the patient does not have acute severe asthma. 1

Key Mortality Risk Factors Identified by Scoring

Scoring systems identify patients at highest risk of death, including those with: 1

• Prior severe, life-threatening episodes or intubation 1
• Recent hospital discharge or emergency department visits 1
• Currently using or recently stopped oral corticosteroids 1
• Overuse of short-acting β-agonists (>1 canister/month) 1
• No current inhaled corticosteroid use 1

Clinical Severity Scoring Parameters

Severe Asthma Features (Immediate Treatment Required)

The British Thoracic Society defines severe asthma by these objective criteria: 1, 2, 3

• Peak expiratory flow (PEF) <50% of predicted or personal best 1, 2, 3
• Respiratory rate >25 breaths/minute 1, 2, 3
• Heart rate >110 beats/minute 1, 2, 3
• Unable to complete sentences in one breath 1, 2, 3

Life-Threatening Features (Highest Mortality Risk)

These parameters mandate immediate aggressive intervention: 1, 2, 4

• PEF <33% of predicted or personal best 1, 2, 4
• Silent chest, cyanosis, or feeble respiratory effort 1, 2, 4
• Bradycardia or hypotension 1, 2, 4
• Exhaustion, confusion, or coma 1, 2, 4
• Normal or elevated PaCO₂ (5-6 kPa or higher) in a breathless patient 1
• Severe hypoxia: PaO₂ <8 kPa despite oxygen 1

How Scoring Triggers Life-Saving Interventions

Immediate Treatment Algorithm Based on Scores

When severe features are present (PEF <50%): 1, 2, 4

• High-flow oxygen (40-60%) 1, 2, 4
• Nebulized salbutamol 5 mg or terbutaline 10 mg via oxygen 1, 2, 4
• Prednisolone 30-60 mg orally OR hydrocortisone 200 mg IV immediately 1, 2, 4

When life-threatening features are present (PEF <33% or other critical signs): 1, 4

• Add nebulized ipratropium 0.5 mg 1, 4
• IV aminophylline 250 mg over 20 minutes OR IV salbutamol/terbutaline 250 µg over 10 minutes 1, 4
• Immediate medical registrar notification and hospital admission 1

Hospital Admission Criteria Driven by Scores

Mandatory admission when: 1, 2

• Any life-threatening features present 1, 2
• PEF <33% after initial treatment 1, 2
• Features of acute severe asthma persist after initial treatment 1, 2

Lower threshold for admission when: 1

• Attack occurs in afternoon or evening 1
• Recent hospital admission or previous severe attacks 1
• Recent nocturnal symptoms 1

Monitoring Response to Treatment

Reassess PEF 15-30 minutes after initial nebulizer treatment: 1, 2

• If PEF improves to >50-75% predicted: Continue high-flow oxygen, prednisolone 1-2 mg/kg daily (maximum 40 mg), and nebulized β-agonist every 4 hours 1
• If PEF remains <50% or patient not improving: Increase nebulized β-agonist frequency to every 30 minutes, add ipratropium, and continue oxygen and steroids 1

ICU Transfer Criteria

Transfer to intensive care unit when: 1

• Deteriorating PEF despite treatment 1
• Worsening exhaustion or feeble respirations 1
• Persistent hypoxia or hypercapnia 1
• Coma, respiratory arrest, confusion, or drowsiness 1

Discharge Criteria Based on Objective Measurements

Patients should not be discharged until: 1, 2

• PEF >75% of predicted or personal best 1, 2
• PEF diurnal variability <25% 1, 2
• Stable on discharge medications for 24 hours 1, 2
• Inhaler technique verified and recorded 1, 2

Self-Management Plans Incorporating Scoring

Written action plans reduce mortality by specifying when patients should: 1, 2

• Self-administer oral steroid tablets when PEF falls below 60% of normal or previously agreed individual threshold 1, 2
• Urgently seek medical attention when treatment is not working 1, 2
• Initiate or increase inhaled steroids based on PEF measurements 1, 2

Action plans demonstrably reduce asthma mortality when combined with objective PEF monitoring. 1 Specialist care increases the likelihood that patients receive written action plans. 1

Critical Pitfalls to Avoid

Common errors that increase mortality: 1, 2

• Failing to obtain objective measurements (PEF or spirometry) 1, 2
• Underuse of corticosteroids during acute attacks 1
• Delaying hospital admission when criteria are met 1
• Discharging patients before PEF reaches >75% predicted 1
• Not providing PEF meters and written action plans at discharge 1, 2

Special Population: "Poor Perceivers"

Some patients fail to recognize worsening asthma severity—a major contributor to fatal outcomes. 1 These patients require objective lung function monitoring more frequently than subjective symptom assessment alone. 1 Allergist-immunologists perform objective measurements more frequently than other physicians. 1

Follow-Up to Prevent Future Mortality

After acute exacerbation, patients require: 1, 2, 3

• GP follow-up within 1 week 1
• Specialist clinic follow-up within 4 weeks 1
• Continued oral steroids and inhaled steroids in addition to bronchodilators 1
• Regular PEF monitoring with symptom diary 1, 2

Inhaled corticosteroids have been associated with significant reductions in risk for fatal and near-fatal asthma exacerbations. 1 Patients managed by specialists are more likely to receive and appropriately use inhaled steroids regularly. 1