Background Ankylosing spondylitis (AS) is a chronic disease resulting in diminished quality of life (QoL). There was no study regarding QoL in Thai patients with AS.

Objectives To identify factors associated with quality of life, measured by EuroQol 5-dimension, 5-level questionnaire (EQ-5D-5L), in patients with AS.

Methods This was a cross-sectional study. Demographic data and outcomes related to health utility or HU [Thai version EQ-5D-5L], disease activity [BASDAI (0–10), ASDAS-ESR or CRP, number of tender (TJC) and swollen joint (SJC), and enthesitis], and functional status [BASFI (0–10) and HAQ (0–3)] were collected. The HU was calculated on the basis of responses to 5-domains using the Thai value set. Regression analysis was used to explore factors associated with each EQ-5D domain and HU. Multiple models using different outcome measures for disease activity and functional status were performed to identify the best predictive model.

Results Among 119 AS patients, most (73%) were male with mean (SD) age of 40.4 (11.6) years. Most (52.9%) were married and 92 (77.3%) were employed. The median (IQR) disease duration, BASDAI, BASFI, and HAQ were 7.5 (11.8) years, 3.2 (3.7), 2.3 (4.2), and 0.4 (0.9), respectively. The mean (SD, range) EQ-5D and VAS were 0.75 (0.20, -0.24–1.00) and 68.8 (18.8, 10–100), respectively. In univariate analysis, higher disease activity, higher functional index score, and more severe peripheral joint involvement were significantly associated with lower HU and moderate to very severe problem in each EQ-5D domain compared with no to mild problem with p<0.05, except SJC which was not associated with mobility problem. Conversely, age, gender, marital status, and disease duration were not associated with any EQ-5D domains or HU. In multivariate regression analysis, disease activity and functional status were significantly associated with HU (Table 1), when adjusted for age. The best predictive model using BASDAI, CRP, and HAQ with adjusted for age correctly predicted 77.4% of the variance in HU, while using BASFI instead of HAQ in the same model yielded slightly lower predictive value of 70.7%.

Conclusions Disease activity and functional status were significantly factors related to QoL and HU in patients with AS. To improve QoL, the aim of treatment should be achieve remission or at least low disease activity and improve or at least maintain function.

Disclosure of Interest P. Chiowchanwisawakit Grant/research support from: Siriraj Research fund, V. Srinonprasert: None declared, W. Katchamart: None declared