BSRBR-AS study: baseline characteristics of biological and non-biological cohorts
| Biological cohort (n=161) | Non-biological cohort (n=416) | Difference* | 95% CI | |
| Age, mean years | 42.4 | 47.0 | −4.6 | −6.6 to 2.5 |
| Male, % | 64.6 | 67.3 | −2.7 | −11.3 to 5.9 |
| Disease duration, mean years | 7.7 | 12.3 | −4.6 | −6.5 to 2.7 |
| Current smokers, % | 21.3 | 11.0 | 10.2 | 3.9 to 16.5 |
| BASDAI | 5.8 | 3.3 | 2.6 | 2.2 to 2.9 |
| BASFI | 5.4 | 2.7 | 2.7 | 2.3 to 3.2 |
| BAS-G§ | 6.7 | 3.2 | 3.4 | 3.0 to 3.9 |
| CRP (mg/dL) | 2.8 | 2.4 | 0.4 | −0.8 to 1.6 |
| ASDAS | 3.4 | 2.3 | 1.1 | 0.9 to 1.3 |
| Physical job, % | 44.8 | 51.0 | −6.2 | −3.1 to 15.5 |
| WPAI measures (in the last 7 days) | ||||
| Absenteeism, % | 10.9 | 2.8 | 8.1 | 4.7 to 11.4 |
| Presenteeism, % | 41.0 | 20.6 | 20.4 | 15.9 to 24.9 |
| Overall work impairment, % | 42.3 | 21.4 | 20.9 | 16.2 to 25.7 |
| Overall activity impairment, % | 51.0 | 24.0 | 27.0 | 22.5 to 31.4 |
*Difference=biological – non-biologic cohort.
ASDAS, Ankylosing Spondylitis Disease Activity Scale; BAS-FI, Bath Ankylosing Spondylitis Functional Index; BAS-G, Bath Ankylosing Spondylitis Global Disease Status; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BSRBR-AS, British Society of Rheumatology Biologics register in Axial Spondyloarthritis; CRP, C reactive protein; WPAI, Work Productivity and Activity Impairment.