Demographic and clinical characteristics of treatment groups at baseline
| Characteristics | SFC group | p-value¶ | |||
| Never# | Low-dose | High-dose | Low | High | |
| Subjects n | 208 | 205 | 271 | ||
| Age yrs | 51.0±114.49 | 51.8±113.35 | 49.2±113.35 | 0.574 | 0.152 |
| Age at asthma onset yrs | 26.8±118.97 | 27.0±119.52 | 22.7±118.43 | 0.947 | 0.018 |
| Female | 152 (73.1) | 144 (70.2) | 181 (66.8) | 0.523 | 0.138 |
| White | 180 (86.5) | 174 (84.9) | 209 (77.1) | 0.630 | 0.009 |
| Smoking status | 0.510 | 0.869 | |||
| Never | 140 (67.3) | 127 (62.0) | 177 (65.3) | ||
| Ex | 63 (30.3) | 73 (35.6) | 86 (31.7) | ||
| Current | 5 (2.4) | 5 (2.4) | 8 (3.0) | ||
| Mini AQLQ | 4.8±1.39 | 5.1±11.20 | 4.5±11.31 | 0.014 | 0.015 |
| ATAQ | 1.8±11.22 | 1.6±11.10 | 2.1±11.18 | 0.067 | 0.005 |
| FEV1 | 74.5±123.02 | 77.9±120.80 | 65.0±120.22 | 0.131 | <0.001 |
| Patients with exacerbations | 114 (54.8) | 86 (42.0) | 187 (69.0) | 0.009 | 0.001 |
| Patients with severe asthma | 84 (40.4) | 68 (33.3) | 179 (66.1) | 0.138 | <0.001 |
Data are presented as mean±sd or n (%), unless otherwise stated. Low: never-on-salmeterol/fluticasone combination (SFC) versus low-dose; high: never-on-SFC versus high-dose; Mini AQLQ: Mini Asthma Quality of Life Questionnaire; ATAQ: Asthma Therapy Assessment Questionnaire; FEV1: forced expiratory volume in one second. #: patients who were never receiving both inhaled corticosteroids and long-acting β-agonists; ¶: derived from an unpaired t-test and Chi-squared test for continuous and categorical variables for low and high, respectively.