Table 2

Comparison of clinical and demographic traits of clustered subjects in the discovery and validation stages

Discovery stage (n=196)Validation stage (n=194)
Cluster 1Cluster 2Cluster 3P valueN usedCluster 1Cluster 2Cluster 3P valueN used
n subjects in cluster6495375210141
Age (years) (mean, SD)67.8 (8.9)66.9 (10.2)68.8 (9.4)0.59218867.1 (8.1)68.5 (7.6)66.2 (8.6)0.239194
Male (%)52 (81.3%)66 (69.5%)23 (62.2%)0.09119638 (73.1%)72 (71.3%)34 (82.9%)0.347194
European ancestry (%)17 (81.0%)29 (82.9%)3 (75.0%)0.8836051 (98.1%)91 (90.1%)38 (92.7%)0.196194
Ever smoker (%)NA15 (62.5%)18 (78.3%)0.3894711 (57.9%)21 (60.0%)17 (85.0%)0.11474
Death observed during study (%)NA6 (25.0%)16 (66.7%)0.0094816 (48.5%)13 (19.7%)12 (57.1%)0.001120
FVC % predicted (median, IQR)63.0 (35.0)70.5 (30.1)60.1 (23.4)0.34215464.3 (23.6)65.0 (24.3)63.1 (15.3)0.467193
DLCO % predicted (median, IQR)35.0 (30.0)45.0 (29.2)34.4 (17.3)0.00913342.1 (26.4)48.2 (21.1)43.4 (20.3)0.069194
FEV1 % predicted (median, IQR)NA74.9 (23.1)65.4 (22.7)0.2164874.8 (21.7)75.2 (22.2)75.4 (17.7)0.91375
GAP index (mean, SD)4.9 (1.4)3.9 (1.5)4.4 (1.7)0.0061324.1 (1.6)4.0 (1.5)4.3 (1.5)0.753193
MUC5B genotype: GG (%)5 (29.4%)11 (27.5%)14 (51.9%)0.230842 (11.8%)6 (19.4%)4 (25.0%)0.78064
MUC5B genotype: GT (%)10 (58.8%)26 (65.0%)10 (37.0%)14 (82.4%)24 (77.4%)12 (75.0%)
MUC5B genotype: TT (%)2 (11.8%)3 (7.5%)3 (11.1%)1 (5.9%)1 (3.2%)0 (0%)
  • Data are presented as count (percentage), mean (SD) or median (IQR). GAP index, Gender, age and physiology index for IPF mortality.20 P value for count data is from a χ2 test, test comparing means is analysis of variance and test comparing medians is the Kruskal-Wallis log rank test. Significant p values (p<0.05) are highlighted in bold. For percentages, the denominator was the number of participants in that cluster with non-missing data for that trait.

  • DLCO, diffusing capacity for carbon monoxide; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; IPF, idiopathic pulmonary fibrosis; MUC5B genotype, genotype for the MUC5B promoter polymorphism rs35705950; NA, data not available.