Table 2.

Comparison of K-Means Clustering and NBS Clustering Results Shows Little Overlap

Variable	NBS1	NBS2	NBS3	NBS4
Relatively resistant smokers	20	10	3	2
Upper lobe predominant emphysema	5	9	1	1
Airway predominant	15	11	0	3
Severe COPD	15	13	1	11

For 120 COPDGene subjects analyzed in both the Castaldi et al¹⁸ phenotype clustering article and the Chang et al³¹ gene expression clustering article, the overlap between clustering assignments was modest. Network-based stratification (NBS) clusters are ordered as in the original manuscript by average level of FEV₁ (ie, NBS1 has highest average FEV₁).