influence of vitamin d status on fatigue in ankylosing spondylitis

Fatigue is a common symptom in ankylosing spondylitis. hypovitaminosis d is one of the factors influencing fatigue during inflammatory rheumatisms. this study aimed to determine the influence of vitamin d deficiency on fatigue in ankylosing spondylitis. in this cross-sectional study, 40 patients with ankylosing spondylitis and 40 patients suffering from low back pain were recruited. clinical and laboratory data, including vitamin d dosage, disease activity, functional impairment, and quality of life, were evaluated using specific and validated scores. fatigue was assessed by the facit-f score. both groups of patients were compound of 27 men and 13 women with a mean of 43.55±12.26 years in the study group and 47.77±13.63 years in the case group, respectively. ankylosing spondylitis was active according to the asdascrp score in 67.5% of cases. all patients were suffering from fatigue with a mean facit-f score of 21.13. severe levels of fatigue were noted in 50% of cases. 92.5% of patients were vitamin d deficient with a mean vitamin d of 16.57±7.15 ng/ml. factors associated with fatigue were: female gender (p=0.05), spinal pain (p<0.001), enthesitis (p<0.001), disease activity (p<0.001), functional impairment (p<0.001), and quality of life (p<0.001). however, smoking was the only factor related to vitamin d deficiency (p=0.05). vitamin d level was not correlated with fatigue (r= -0.02, p=0.91). in our study, vitamin d status did not seem to have an impact on fatigue in patients with ankylosing spondylitis.