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Background: There remains substantial unmet need to study work disability (WD) in early axSpA. Previous studies suggest that treatment interventions alone do not improve work outcomes and that socioeconomic (SE) as well as clinical factors may play an important role.
Objectives: To investigate the occurrence of WD and the impact of clinical and SE factors on WD in early axial spondyloarthritis (axSpA).
Methods: Patients with a clinical diagnosis of axSpA from the DESIR cohort up to 5 years of follow-up (6-month visits in the first 2 years, followed by annual visits) were studied. Time to WD and potential baseline and time-varying predictors were explored, with a focus on SE variables: age, gender, smoking status since last visit, ethnicity (Caucasian vs other), job type based on ‘collar’ (blue vs white), educational status (low vs high -university), marital status (married vs not) and parental status (number of children); and clinical factors: disease activity (ASDAS/BASDAI), function (BASFI), mobility (BASMI), at each time point. The incidence of WD was calculated as the number of WD events over the total number of person-days under observation. Univariable analyses, followed by collinearity and interaction tests, guided subsequent multivariable Cox survival analyses.
Results: A total of 704 axSpA patients with work-related data, mean (SD) age 33.8 (8.6), were studied. The estimated incidence of WD amongst those at risk and across the five years of DESIR, was 0.05 (95% CI 0.03, 0.06) per 1000 days (total person-days of observation of 999,999). Mean (SD) time to WD was 976 days (SD 476), (min 163, max 2021 days). In people who developed WD, 25% did so at 595 days; 50% and 75% at 1050 and 1433 days, respectively. Significant differences in age, level of education, marital and parental status as well as disease activity, function and mobility, all at baseline, were seen between those developing WD vs those who never did. In multivariable models (
Univariable and multivariable model analyses with WD as outcome.
| Type of analysis | Univariable |
Multivariable model
|
Multivariable model
|
| HR (95% CI ) |
HR (95% CI
)
|
HR (95% CI
)
|
|
| Explanatory variables | |||
| Age | 1.07 (1.04, 1.11) | 1.06 (1.02, 1.10) | 1.03 (0.99, 1.08) |
| Male gender | 0.68 (0.37, 1.23) | 1.10 (0.58, 2.08) | 1.00 (0.50, 2.02) |
| High education | 0.25 (0.14, 0.48) | 0.57 (0.29, 1.11) | 0.42 (0.19, 0.90) |
| Parental status | 1.36 (1.09, 1.70) | NS | NS |
| ASDAS (CRP) | 2.40 (1.77, 3.26) | 1.79 (1.27, 2.54) | Not tested |
| BASFI, 0-10 | 1.54 (1.36, 1.75) | 1.42 (1.22, 1.65) | 1.53 (1.29, 1.81) |
| BASMI, 0-10 | 2.13 (1.65, 2.75) | NS | 1.49 (1.10, 2.00) |
| Symptom duration | 0.79 (0.56, 1.12) | NS | NS |
| HLA B27 positive | 0.64 (0.36, 1.13) | NS | NS |
| Hip involvement (baseline) vs not | 1.98 (1.02, 3.82) | NS | NS |
| Comorbidity count | 2.33 (1.68, 3.21) | NS | NS |
| NSAID use last 6m (vs no use) | 1.01 (1.00, 1.02) | NS | NS |
| Oral Corticosteroid use (vs no) | 2.72 (1.27, 5.83) | NS | NS |
| csDMARD use last 6m (vs no) | 2.20 (0.90, 5.41) | NS | NS |
| TNFi use | 2.15 (1.19, 3.87) | NS | NS |
NS=Not significant
Conclusion: In this early axSpA cohort, WD was an infrequent event. Nevertheless, clinical factors are amongst the strongest predictors of WD, over SE factors, with worse disease activity, function and mobility all independently implicated with more WD in early axSpA. Disease severity remains a strong predictor of adverse work outcome, despite substantial advances in therapeutic strategies in axSpA.
Disclosure of Interests: None declared.