A pooled analysis of 16S rRNA amplicon sequencing data from 3,127 lower airway samples (2,152 asthmatic patients, 975 healthy controls; 12 independent cohorts globally) was used to derive and validate a phylum-level Asthma Dysbiosis Index (ADI = log₁₀[(Actinobacteria + Fusobacteria) / (Proteobacteria + Bacteroidetes)]) for distinguishing asthmatic from healthy airways across pediatric (n=1,695) and adult (n=457) populations.
The ADI distinguished asthmatic from healthy airways with an AUC of 0.81 overall (p < 10⁻¹⁷⁰); performance held in pediatric (AUC = 0.80) and adult (AUC = 0.84) sub-cohorts, outperforming simpler two-phylum ratios (e.g., Actinobacteria/Proteobacteria alone: AUC = 0.76).
- 16S rRNA data limits resolution to phylum level only; species-specific characterization is not possible. - Retrospective cross-sectional design prevents assessment of temporal stability during exacerbations or disease control. - Healthy controls are predominantly adults (from COPDMAP/HMP), creating a mismatch with the largely pediatric asthma cohort.
The ADI formula uses standard phylum-level relative abundances and can be applied directly to existing microbiome datasets without special tools. Prospective validation is still needed before clinical use, but the formula offers a simple, age-independent starting point for airway dysbiosis monitoring in both children and adults.
