Background:Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare disease, characterized by osteoarticular and cutaneous manifestations. Osteitis and hyperostosis are regarded as the core pathophysiological changes of SAPHO syndrome [1], which may lead to bone pain and loss of motor function. The Work Productivity and Activity Impairment (WPAI) questionnaire is an instrument to measure the impact of the disease on work productivity and activity, subsequently adapted for ankylosing spondylitis [2], rheumatoid arthritis [3], irritable bowel syndrome [4], and other chronic diseases [5]. However, no study has investigated the work productivity of patients with SAPHO syndrome.Objectives:The purpose of this study is to give an overview of work productivity loss in SAPHO patients through the work productivity and activity impairment (WPAI) questionnaire and investigate the relationship between the WPAI and other disease-related indicators.Methods:Patients for this cross-sectional study were recruited from Peking Union Medical College Hospital (Beijing, China). The questionnaires incorporating the WPAI were administered, along with demographic data, disease-specific measures, and general health variables. The construct validity of WPAI was evaluated by the correlations between WPAI outcomes and other measures. Wilcoxon rank-sum tests and non-parametric Kruskal-Wallis tests were used for comparison of WPAI outcomes between known-groups.Results:A total of 376 patients were included and 201 patients (53.5%) were employed. The median (interquartile range [IQR]) of absenteeism, presenteeism, work productivity loss and activity impairment were 0% (0-13%), 20% (0-40%), 20% (0-52%) and 30% (0-50%), respectively. All WPAI outcomes showed moderate to strong correlations to other generic and disease-specific measures (|r| =0.43-0.75), except for absenteeism. Increasing disease activity and worse health status are significantly associated with higher impairment of work productivity and activity.Conclusion:This study highlights the negative effects of SAPHO syndrome on patients’ work productivity and activity, indicating a good construct validity and discriminative ability of WPAI. For reducing the economic burden, it is important to improve the patients’ work productivity and daily activity with active intervention.References:[1]Liu S, Tang M, Cao Y, Li C. Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: review and update. Therapeutic advances in musculoskeletal disease. 2020;12:1759720x20912865.[2]Reilly MC, Gooch KL, Wong RL, Kupper H, van der Heijde D. Validity, reliability and responsiveness of the Work Productivity and Activity Impairment Questionnaire in ankylosing spondylitis. Rheumatology (Oxford, England). 2010;49(4):812-819.[3]Zhang W, Bansback N, Boonen A, Young A, Singh A, Anis AH. Validity of the work productivity and activity impairment questionnaire--general health version in patients with rheumatoid arthritis. Arthritis research & therapy. 2010;12(5):R177.[4]Frandemark A, Tornblom H, Jakobsson S, Simren M. Work Productivity and Activity Impairment in Irritable Bowel Syndrome (IBS): A Multifaceted Problem. The American journal of gastroenterology. 2018;113(10):1540-1549.[5]Enns MW, Bernstein CN, Kroeker K, Graff L, Walker JR, Lix LM, et al. The association of fatigue, pain, depression and anxiety with work and activity impairment in immune mediated inflammatory diseases. PloS one. 2018;13(6):e0198975.Disclosure of Interests:None declared