Bronchiectasis Severity Index (BSI) Calculator
Enter the patient data below to estimate BSI score and severity class (low, intermediate, or high). This tool is for educational and clinical support use only.
What is the Bronchiectasis Severity Index?
The Bronchiectasis Severity Index (BSI) is a clinical scoring system used to estimate disease severity and future risk in people with non-cystic fibrosis bronchiectasis. It combines symptoms, lung function, exacerbation history, microbiology, and imaging findings into one numerical score.
In practice, the BSI helps clinicians stratify patients into low, intermediate, or high-risk groups. This can support decisions about follow-up intensity, airway clearance planning, exacerbation prevention, and specialist referral.
Variables Included in the BSI Score
1) Age
Older age increases risk and therefore contributes more points to the score.
2) Body Mass Index (BMI)
Low BMI can reflect frailty, poorer reserve, or increased disease burden. In BSI, BMI below 18.5 kg/m² adds points.
3) FEV1 % Predicted
Lower FEV1 indicates more severe airflow limitation and contributes progressively higher points.
4) Exacerbation and Hospitalization History
Frequent exacerbations and prior severe events requiring hospital admission are major predictors of future outcomes.
5) Dyspnea (MRC Scale)
The Medical Research Council dyspnea scale captures functional breathlessness. Higher scores indicate greater functional limitation and higher risk.
6) Chronic Airway Infection
Chronic colonization with Pseudomonas aeruginosa is associated with worse prognosis and receives a higher point allocation than other pathogenic organisms.
7) Radiological Extent
More extensive disease on CT (three or more lobes involved or cystic change) contributes additional risk points.
How to Interpret the Result
- Low severity: BSI 0–4
- Intermediate severity: BSI 5–8
- High severity: BSI 9 or more
Higher categories are linked to greater risk of future exacerbations, admissions, and mortality. This does not predict any single individual outcome with certainty, but it is useful for population-level risk stratification and longitudinal follow-up planning.
When a BSI Calculator is Most Useful
- Initial specialist clinic assessment
- Review after recurrent exacerbations
- Baseline risk discussion with patients
- Supporting decisions on monitoring frequency
- Research and audit workflows in bronchiectasis services
Important Limitations
No score should be used in isolation. The BSI does not directly capture all clinically meaningful dimensions, such as quality-of-life trajectories, all comorbidity effects, immunologic status, or treatment adherence. Clinical context remains essential.
Also, inputs should come from reliable data sources (recent spirometry, documented microbiology, and confirmed CT findings). Inaccurate source data can significantly change categorization.
Practical Next Steps After Scoring
If score is low
Continue routine care, optimize airway clearance technique, encourage vaccination and prompt exacerbation action plans, and maintain periodic reassessment.
If score is intermediate
Consider closer interval follow-up, review sputum microbiology trends, reinforce adherence to airway clearance and inhaled therapies, and evaluate exacerbation prevention strategies.
If score is high
Prioritize specialist-led management, assess for chronic suppressive strategies when appropriate, monitor closely for decline, and coordinate multidisciplinary support (respiratory therapy, nutrition, and pulmonary rehabilitation where indicated).
Final Note
This bronchiectasis severity index calculator is designed to make evidence-based scoring fast and transparent. Use it as part of comprehensive respiratory care, not as a standalone diagnostic or treatment decision engine.