Predictors of Adverse Work Outcomes in Ankylosing Spondylitis

Patients with ankylosing spondylitis (AS) on work disability experienced further adverse work outcomes over a 12-year period, according to data published in Arthritis Care and Research.

Researchers selected 215 patients from the Outcome Assessments in Ankylosing Spondylitis International Study, which includes patients from the Netherlands, France, and Belgium, to be included in the analysis. Fifty-five patients (26%) were on full work disability at baseline, and 139 (65%) were at risk for adverse work outcomes during the follow-up period.

They compared the standardized work disability rates over 12 years to that of the general population, and used Cox survival analyses to identify the baseline predictors and time-varying factors that could influence adverse work outcomes over the follow-up period.

“The longer withdrawal rate in longstanding disease, compared to the first years after diagnosis, suggests that withdrawal from work seems to be attenuated in longstanding disease,” the authors wrote. “Likely, those with the highest risk for work loss had withdrawn from work in the years before entering into our cohort, resulting lower, but still increased, standardized [work disability] rates.”

Work disability increased consistently among Dutch men (incidence rate [IR}: 2.9: 95% confidence interval [CI]: 1.2-4.6), but increased less clearly among women (IR: 1.2; 95% CI: -0.4-2.9).

Baseline predictors of adverse work outcomes included residence in the Netherlands compared with France or Belgium (hazard ratio [HR]: 3.4; 95% CI: 1.4-8.4) and worsened Bath Ankylosing Spondylitis Functional Index (BASFI) (HR: 1.2; 95% CI: 1.0-1.4). Time-varying predictors over 12 years were residence in the Netherlands, uveitis, and BASFI with age and inflammatory bowel disease.

“The large influence of country of residence requires further study into which aspects of the health care, economic, and social security system are either barriers to or facilitators of healthy labor force participation,” the authors noted. “For clinical studies, that influence points to the importance of stratifying trials with work outcomes according to country of residence.”

Summary and Clinical Applicability

Work disability can have economic consequences for patients with chronic diseases, but it can also impact self-esteem, emotional life, and autonomy of the persons experiencing the disease. In order to understand the impact of AS on work disability, researchers compared the 12-year work disability rates of patients with AS compared with the general population and explored factors that could affect work disability or a reduction in working hours.

The results of the current study suggest that country of residence may impact work disability rates for this patient population, although this requires further study. In addition, the researchers found that women had a higher withdrawal rate from work than men during the first years of the disease, but a lower rate towards the end of the follow-up period. Therefore, future studies should examine these discrepancies of work disability rates between men and women.

Limitations and Disclosures

The national population used for analysis in this study was limited thus limiting generalizability. 

Two study co-authors have disclosed receiving consultant, speaking fees, or honoraria from  AbbVie, Amgen, Janssen, Merck, Novartis, Pfizer, and UCB.

Reference

Castillo-Ortiz JD, Ramiro S, Landewe R, et al. Work outcome in patients with ankylosing spondylitis: Results from a 12-year followup of an international study. Arthrit Care Res. 2016;68(4): 544-552. doi: 10.1002/acr.22730.