Hospitalization Only (n=55,815) ICU(n=5,335) Standardized Difference† Age, in years       0-4 23,899 (42.8%) 614 (11.5%) 0.65 5-9 6,382 (11.4%) 261 (4.9%) 0.21 10-14 2,243 (4.0%) 189 (3.5%) 0.02 15-19 1,293 (2.3%) 217 (4.1%) 0.11 20-29 2,406 (4.3%) 408 (7.6%) 0.16 30-39 2,703 (4.8%) 552 (10.3%) 0.25 40-49 3,505 (6.3%) 665 (12.5%) 0.25 50-59 3,607 (6.5%) 623 (11.7%) 0.21 60-69 3,048 (5.5%) 630 (11.8%) 0.27 70+ 6,729 (12.1%) 1,176 (22.0%) 0.30 Sex       Female 28,078 (50.3%) 3,272 (61.3%) 0.22 Male 27,737 (49.7%) 2,063 (38.7%)   Rurality       Rural 6,530 (11.7%) 763 (14.3%) 0.08 Urban 49,258 (88.3%) 4,569 (85.7%)   Income Quintile       1 (lowest income) 13,918 (25.1%) 1,432 (27.0%) 0.04 2 11,912 (21.5%) 1,185 (22.4%) 0.02 3 11,125 (20.1%) 1,026 (19.4%) 0.02 4 10,093 (18.2%) 942 (17.8%) 0.01 5 (highest income) 8,438 (15.2%) 717 (13.5%) 0.05 Comorbidities       Children (≤19) (n=33,817) (n=1,281)   Asthma-related conditions 33,190 (98.1%) 1,253 (97.8%) 0.02 Other respiratory conditions 3,596 (10.6%) 334 (26.1%) 0.49 Diabetes 90 (0.3%) 14 (1.1%) 0.15 Any of the above comorbidities 33,194 (98.2%) 1,253 (97.8%) 0.03 Adults (≥20) (n=21,998) (n=4,054)   Asthma-related conditions 21,766 (98.9%) 3,998 (98.6%) 0.03 Other respiratory conditions 11,626 (52.9%) 2,142 (52.8%) 0.00 Diabetes 5,408 (24.6%) 1,177 (29.0%) 0.10 Lung cancer 163 (0.7%) 37 (0.9%) 0.02 Cancer (other than lung) 1,889 (8.6%) 394 (9.7%) 0.04 COPD 9,699 (44.1%) 1,910 (47.1%) 0.06 Hypertension 10,829 (49.2%) 2,089 (51.5%) 0.05 CHF 3,687 (16.8%) 944 (23.3%) 0.17 AMI 953 (4.3%) 426 (10.5%) 0.28 Stroke 2,649 (12.0%) 485 (12.0%) 0.00 IHD 6,969 (31.7%) 1,448 (35.7%) 0.09 Angina 4,933 (22.4%) 1,063 (26.2%) 0.09 Any of the above comorbidities 21,881 (99.5%) 4,034 (99.5%) 0.01 Mechanical Ventilation       No 72 (0.1%) 1,395 (26.1%) 1.94 Yes 55,743 (99.9%) 3,940 (73.9%)   Death       Yes 4,545 (8.1%) 1,149 (21.5%) 0.46 No 51,270 (91.9%) 4,186 (78.5%)

Note: †Standardized difference=difference in means or proportions divided by standard error; imbalance defined as absolute value greater than 0.20 (small effect size).

ICU=intensive care unit; COPD=chronic obstructive pulmonary disease; CHF=congestive heart failure; AMI=acute myocardial infarction; IHD=ischemic heart disease; This table includes unique persons at time of their first ICU visit, or first hospitalization for asthma (if they did not have an ICU visit). Index date is the discharge date of the first asthma hospitalization or the first ICU during the study period (April 1, 2003 - March 31, 2013); Age group, rurality, income quintile were identified at the index date; Mechanical ventilation and death were identified at the end of the study. All comorbidities were identified using information before the index date. Percentages were adjusted for missing data.

Table 1: Descriptive profile of asthma prevalence population (n=1,946,544) hospitalized at least once, from 2003 to 2012.