Poisson regression analysis for the number of viral symptoms
| Rate ratio (95% CI) | P value | |
| Age (per decade) | 0.96 (0.94 to 0.99) | 0.014 |
| Female sex | 1.72 (1.59 to 1.87) | <0.001 |
| Control | 1 (Ref.) | – |
| RA | 0.68 (0.59 to 0.80) | <0.001 |
| IBD | 1.06 (0.92 to 1.20) | 0.425 |
| SpA | 0.86 (0.72 to 1.01) | 0.072 |
| Other IMIDs | 0.99 (0.84 to 1.16) | 0.897 |
| Psoriasis | 0.99 (0.81 to 1.20) | 0.895 |
IBD, inflammatory bowel disease; IMIDs, immune-mediated inflammatory diseases; RA, rheumatoid arthritis; SpA, spondyloarthritis.