Development of a prognostic model of work disability in patients with axial spondyloarthritis and its application in real-world clinical practice

Abstract

Objective: to develop a model for predicting work disability in patients with axial psoriatic arthritis (axPsA) and ankylosing spondylitis (AS). Material and methods . The study included 74 patients with psoriatic arthritis and spinal involvement (axPsA) who met the CASPAR criteria (2006), and 44 patients with AS who met the modified New York criteria for AS (1984). A standard rheumatological examination was performed, including determination of the tender and swollen joint counts (TJC/68 and SJC/66 for PsA or TJC/44 and SJC/44 for AS), serum CRP level (mg/L), DAPSA/ASDAS arthritis/spondylitis activity indices, physician global assessment of disease activity using a visual analog scale (VAS, mm) and a numerical rating scale (NRS), and patient global assessment of health, including disease activity according to BASDAI, pain intensity and disease activity according to NRS and VAS in mm, fatigue according to the FACIT-F scale, fibromyalgia according to the FiRST questionnaire, and work productivity according to the WPAI-SPH questionnaire, including hours missed due to illness according to the presenteeism scale. Multivariate stepwise discriminant analysis was performed to identify predictors of work disability. Results and discussion . Based on a combination of significant factors, the following prognostic model of work disability was developed: -1.868 × FACIT-F (1 – severe fatigue; 2 – fatigue; 3 – no fatigue) + 1.194 × CRP (mg/L) + 0.846 × question 5 of the FiRST questionnaire (0 – no; 1 – yes) + 0.08 × SJC. The Pwork disability value was calculated; a value -2.812 corresponds to 20% of working hours missed due to illness according to the presenteeism scale. At Pwork disability <-2.812, the patient is able to work, and the proportion of working hours missed due to illness is <20%. Conclusion . A prognostic model for assessing work disability has been developed. By taking significant factors into account, this model will enable physicians to adjust treatment in a timely manner and reduce the risk of further patient disability.