Background It is increasingly recognized that restrictions in work productivity while at work can be a predictor of future sick leave and withdrawal from labour force. At work productivity is a complex outcome and in addition to the physical impairments, also the environmental and personal context of the patients might contribute to work outcome. However, there are only limited data that help to understand the relative importance of these factors with regard to worker participation in patients with active AS with a paid work

Objectives To understand contribution of health-related and work-related contextual factors on at work productivity restrictions in patients with AS with active disease.

Methods Patients who were eligible to start a biological and working for pay, completed a questionnaire on health (BASDAI, BASFI), the Work Productivity & Activity Impairment scale (WPAI) to assess absence and limitations in work productivity the last 7 days, and a large number of work characteristics comprising type of work, characteristics of workplace, satisfaction with contact with colleagues and importance of work in life. Multivariable regression models were computed to retrieve the model that explains best,which work related factors contributed to at work productivity limitations after adjusting for demographic (age and gender) and disease characteristics (disease duration, BASDAI, BASFI).

Results 73 patients were included. 36 (49%) were male, age was 38 (sd:9) years, (sd:8.6) Disease duration (symptoms) was 10.8years, BASDAI 6.0 (1.7) and BASFI 5.2 (1.1). Patients worked on average 38 hours per week. 45 (63%) had a mainly manual profession, importance of work for life was 8.1 (1.9) (10 max) and quality of contact with colleagues was 8.0 (1.3) (max 10). 10 patients had been absent of which 6 (9%) due to AS.

WPAI productivity limitations while at work was 48.7% (23.7). The table presents the best fitting model for at work productivity limitations.

Conclusions For patients with AS that are eligible to start a biological, work is important for their life. Patients incur substantial restrictions in at work productivity. In addition to female gender and BASFI, the quality of contact with the colleagues was the only work related factor that contributed significantly to limitations in at work productivity. This offers additional opportunities to improve work outcome

Disclosure of Interest A. Boonen Grant/Research support from: Amgen, Abbott, Speakers Bureau: Pfizer, C. Boone Employee of: Pfizer, A. Albert: None Declared, H. Mielants Speakers Bureau: Astra Zeneca, MSD, Pfizer