Background: Inflammatory back pain and stiffness are the leading symptoms of ankylosing spondylitis (AS). AS progression leads to substantial functional impairment and can reduce quality of life (QoL). The aim of this study was to determine the impact of disease activity on QoL, fatigue, functional status and physical activity.
Subjects and methods: One hundred and fifty AS patients were included in the study, their body mass index (BMI) was calculated and they completed questionnaires regarding disease activity (The Bath Ankylosing Spondylitis Disease Activity Index, BASDAI) functional status (The Bath Ankylosing Spondylitis Functional Index, BASFI) spinal mobility (The Bath Ankylosing Spondylitis Metrology Index, BASMI), physical activity (the International Physical Activity Questionnaire, IPAQ), functional disability (The Health Assessment Questionnaire Disability Index, HAQ-DI), fatigue (The Functional Assessment of Chronic Illness Therapy - fatigue, FACIT-F) and QoL (The Short Form Survey-36, SF-36).
Results: Patients with inactive disease (BASDAI<4) had significantly better HAQ scores (p=0.001), SF-36 mental component scores - MCS (65.68±19.54 inactive vs. 46.89±21.78 active disease, p=0.001), SF-36 physical component scores - PCS (median score 56.25 inactive vs. 30.00 active disease, p=0.001) and FACIT-F scores (38.49±10.62 inactive vs. 26.21±10.81 active disease, p=0.001). There was no significant difference in patient's physical activity or BMI regarding disease activity (p=0.564 and p=0.162 respectively). Also, there was no significant difference in BASDAI, BASMI or BASFI scores regarding different BMI categories (p=0.818, p=0.474, p=0.436, respectively).
Conclusion: AS activity increased fatigue, impaired functional ability and QoL, especially the physical component. Although more than half (61.4%) of our patients were categorized as pre-obese or obese according to BMI, this was not related to disease activity, spinal mobility or daily functioning scores. Reported physical activity level had no effect on disease activity. Disease activity influences the course of AS and QoL assessment should be implemented into regular AS evaluation in order to improve treatment outcome.