Spearman correlation between ASAS Health Index scores and other PRO
| Hypothesis | Spearman correlation | Confirmation* | |
| Pain | High | 0.60 | Yes |
| Spinal pain | High | 0.54 | Yes |
| Patient global | High | 0.57 | Yes |
| Physician global | Moderate | 0.49 | Yes |
| ASDAS | High | 0.61 | Yes |
| BASDAI | High | 0.70 | Yes |
| BASFI | High | 0.71 | Yes |
| HADS anxiety | Moderate | −0.55 | No |
| HADS depression | Moderate | −0.57 | No |
| EQ-5D VAS (0–100 mm) | High | 0.45 | No |
| EQ-5D | High | −0.72 | Yes |
| SF-36 PSC | High | −0.73 | Yes |
| SF-36 MSC | Moderate | −0.59 | No |
| WPAI presenteeism | Moderate | 0.60 | No |
| WPAI absenteeism | Moderate | 0.38 | Yes |
| Well-being last week | High | 0.61 | Yes |
*Column indicates whether hypothesis generated prior to analysis about magnitude and direction of correlation was confirmed in the specific variable.
ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; EQ-5D, Euro Quality of Life 5 Dimensions; HADS, Hospital Anxiety Depression Scale; MSC, mental sum component; PSC, physical sum component; SF-36, Short Form 36; VAS, Visual Analogue Scale; WPAI, Work Productivity and Impairment Scale.