Demographic, clinical, PRO and WPAI–axSpA characteristics of the full study population and the ≤47 and >47 years age subgroups
| Characteristics | Full study population (n=770) | ≤47 years group (n=384) | >47 years group (n=386) | P value |
| General demographics | ||||
| Male, % (n) | 61.6 (474) | 64.6 (248) | 58.5 (226) | 0.085 |
| Age (years), mean±SD | 47.1±12.5 (19–81) | 36.6±6.9 (19–47) | 57.5±6.8 (18–81) | <0.001 |
| BMI (kg/m2) | 28.0±11.9 | 26.9±10.9 | 29.0±12.1 | 0.012 |
| University or college degree, % (n) | 27.0 (208) | 29.7 (114) | 24.4 (94) | 0.096 |
| Clinical characteristics | ||||
| Time of diagnosis (years), mean±SD | 13.4±11.9 | 9.6±9.1 | 17.3±13.0 | <0.001 |
| PROs | ||||
| BASDAI score (range 0–10), mean±SD | 3.9±2.2 | 3.6±2.3 | 4.2±2.0 | <0.001 |
| BASFI score (range 0–10), mean±SD | 3.4±2.5 | 2.6±2.3 | 4.2±2.4 | <0.001 |
| ASAS-HI score (range 0–17), mean±SD | 6.6±3.8 | 5.9±3.9 | 7.3±3.7 | <0.001 |
| WPAI-axSpA (n=590) | ||||
| Employed, % (n) Impairments in daily activity (0–10, n=695), mean (Numerical Rating Scale)±SD | 76.6 (590) 4.1±2.6 | 88.5 (340) 3.8±2.7 | 64.8 (250) 4.6±2.4 | <0.001 <0.001 |
| Missed hours from work because of axSpA during the past 7 days, mean±SD | 3.8±10.3 | 3.8±10.8 | 3.8±9.5 | 0.980 |
| Missed hours from work during the past 7 days because of any other reason, such as vacation, holidays, time off to participate in this study, mean±SD | 6.0±12.7 | 5.9±12.5 | 6.1±13.0 | 0.836 |
| Hours actually worked during the past 7 days, mean±SD | 28.9±17.1 | 29.8±16.6 | 27.7±17.6 | 0.143 |
| Presenteeism during the past 7 days, mean±SD | 32.6%±25.6% | 29.3±25.4% | 37.0±25.4% | <0.001 |
| Absenteeism during the past 7 days, mean±SD | 10.6%±26.2% | 9.2%±24.8% | 12.5%±28.0% | 0.004 |
| 0 (no absenteeism), % (n) | 81.9 (483) | 85.0 (289) | 77.6 (194) | 0.021 |
| Total impairment calculated as absenteeism score/(1−absenteeism score)×presenteeism score) resulting in a range from 0% to 100% with higher percentages indicating higher impairment, mean±SD | 36.6%±29.6% | 33.9%±29.3% | 41.7%±29.5% | 0.003 |
*Results of the WPAI–axSpA are only presented for employed patients (n=590) unless otherwise noted.
ASAS-HI, Assessment of SpondyloArthritis International Society–Health Index; axSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BMI, body mass index; BMI, body mass index; PRO, patient-reported outcome; WPAI, Work Productivity and Activity Impairment Questionnaire.