Background Disease activity has an important impact on work productivity in patients with Ankylosing Spondylitis (AS). However, knowledge is limited if this impact exists in early axial Spondyloarthritis (axSpA) patients and if it is similar in different subgroups of patients such as male vs. female patients.
Objectives To investigate if the impact of disease activity, assessed by ASDAS (AS Disease Activity Score, CRP based), on work productivity is similar according to gender, age, medication use, profession, HLA-B27 positivity, and duration of back pain at baseline in early axSpA patients.
Methods The SPACE-cohort includes patients (chronic back pain ≥3 months, ≤2 years, onset <45 years) recruited from 5 European centres. Patients who fulfilled the ASAS criteria for axSpA were included in this analysis. Work Productivity and Activity Impairment questionnaire (WPAI) was completed by patients at baseline to assess the impact of axSpA on Work Productivity Loss (WPL; i.e. total work impairment due to disease), presenteeism (i.e. decreased functionality at work due to disease), and absenteeism (i.e. absence at work due to disease) in the past 7 days. Higher scores indicate greater impairment (ranged 0–100). ASDAS was used to assess disease activity. Gender, age, medication use, profession, HLA-B27 positivity, and duration of back pain were tested for effect modification (cut-off of p<0.20) one by one in a linear regression model. Continuous variables were split by their median.
Results In total, 87 axSpA patients working at baseline were included; 53 patients of them fulfilled the clinical arm and 34 patients the imaging arm of the ASAS axSpA criteria. Patients were on average 30.8 years old (SD 7.6), 52.9% was male, and had a mean duration of back pain of 13 months (SD 7.1). They worked on average 29.5 (SD 15.8) hours and missed 3.0 (SD 8.0) hours per week at work due to axSpA. Mean WPL, presenteeism, and absenteeism were 34.3% (SD 28.5), 31.4% (SD 25.3), and 8.2% (SD 20.1) respectively. Patients had a mean ASDAS of 2.3 (SD 0.9). The univariable model (Figure 1) shows that one point increase in ASDAS resulted in an increase of 19.3%, 16.9%, 8.7% in WPL, presenteeism, and absenteeism, respectively. Fulfilment of the clinical or imaging arm was not an effect modifier (not shown). Gender and duration of back pain were effect modifiers in the associations between ASDAS and WPL, presenteeism, and, absenteeism. Results were stratified for these variables. The associations remained statistically significant in all stratified models, except in the model of absenteeism for males (p=0.207).
Conclusions Disease activity is positively associated with WPL, presenteeism, and absenteeism in early axSpA patients. The same level of disease activity seems to have more adverse impact on work productivity in women than in men, and irrespective of that, in patients with relatively long disease duration. In addition to disease activity, gender, and disease duration are relevant contextual factors in explaining WPL in patients with early axSpA.
Disclosure of Interest None declared