Table 3.
Multivariable stratified analysis exploring determinants of employment in subjects aged≤65 years
| Variable | Controls (n=465) | AS—low education (n=145) | AS—high education (n=68) | ||||||
| IRR | CI | P values | IRR | CI | P values | IRR | CI | P values | |
| Age, years | 1.00 | 0.99 to 1.00 | 0.07 | 0.98 | 0.97 to 0.99 | <0.01 | 0.99 | 0.98 to 1.01 | 0.21 |
| Gender, male | 1.08 | 0.99 to 1.19 | 0.09 | 1.22 | 0.92 to 1.61 | 0.17 | 0.96 | 0.72 to 1.26 | 0.75 |
| Comorbidity (SCQ, 0–39) | 0.97 | 0.94 to 1.01 | 0.14 | * | * | ||||
| BMI, kg/m2 | † | † | † | ||||||
| Smoking, current | † | † | † | ||||||
| Alcohol use, current | * | * | * | ||||||
| SF-36 PCS (0–100) | 1.01 | 1.00 to 1.02 | 0.02 | 1.02‡ | 1.00 to 1.03 | 0.02 | 1.01 | 1.00 to 1.03 | 0.05 |
| SF-36 MCS (0–100) | * | † | † | ||||||
| Mastery (7–28) | * | 1.04 | 1.01 to 1.08 | 0.02 | * | ||||
| Education, high | 1.09 | 1.01 to 1.18 | 0.02 | n/a | n/a | n/a | n/a | n/a | n/a |
Due to missing data, 213 (of 214) AS patients and 465 (of 470) controls were included in this analysis.
* Variable tested in multivariable analysis, but not significant and no confounder in multivariable analysis (therefore not included in model).
Variable not tested in multivariable analysis, due to absence of association with outcome in univariable analysis (p≥0.20).
‡ Confounder. n/a: as the AS samples were stratified by education, education itself could not be included in the multivariable model as independent variable.
AS, ankylosing spondylitis; BMI, body mass index; IRR, incidence rate ratio; SCQ, Self-Administered Comorbidity Questionnaire; SF-36 PCS, Short-Form 36 Physical Component Summary; SF-36 MCS, Short-Form 36 Mental Component Summary.