Search

Objective: While vitamin D regulates immune cells, little is known about it in autoimmune Addison's disease (AAD). We investigated the vitamin D status in AAD patients from five European populations to assess its deficiency. In addition, we studied two case-control cohorts for vitamin D metabolism and pathway genes. Design: Cross-sectional study. Methods: A total of 1028 patients with AAD from Germany (n = 239), Italy (n = 328), Norway (n = 378), UK (n = 44) and Poland (n = 39) and 679 controls from Germany (n = 301) and Norway (n = 378) were studied for 25(OH)D3 (primary objective). Secondary objectives (1,25(OH)2D3 and pathway genes) were examined in case-controls from Germany and Norway correlating 25(OH)D3 and single nucleotide polymorphisms within genes encoding the vitamin D receptor (VDR), 1-α-hydroxylase (CYP27B1), 25-hydroxylase (CYP2R1), 24-hydroxylase (CYP24A1) and vitamin D binding protein (GC/DBP). Results: Vitamin D deficiency (25(OH)D3 10-20 ng/mL) was highly prevalent in AAD patients (34-57%), 5-22% were severely deficient (<10 ng/mL), 28-38% insufficient (20-30 ng/mL) and only 7-14% suffici ent (>30 ng/mL). Lower 25(OH)D3 and 1,25(OH)2D3 levels were observed both in Norwegian and German AAD (P = 0.03/0.003 and P = 1 x 10-5/< 1 x 10-7, respectively) the former was associated with CYP2R1 (rs1553006) genotype G. Whereas controls achieved sufficient median 25(OH)D3 in summers (21.4 to 21.9 ng/mL), AAD patients remained largely deficient (18.0 to 21.2 ng/mL) and synthesize less 1,25(OH)2D3. Conclusion: Vitamin D deficiency and insufficiency are highly prevalent in AAD patients. The vitamin D status of AAD may be influenced by genetic factors and suggests individual vit amin D requirements throughout the year. [ABSTRACT FROM AUTHOR]

Context: Patients with Addison's disease (AD) self-report impairment in specific dimensions on well-being questionnaires. An AD-specific quality-of-life questionnaire (AddiQoL) was developed to aid evaluation of patients., Objective: We aimed to translate and determine construct validity, reliability, and concurrent validity of the AddiQoL questionnaire., Methods: After translation, the final versions were tested in AD patients from Norway (n = 107), Sweden (n = 101), Italy (n = 165), Germany (n = 200), and Poland (n = 50). Construct validity was examined by exploratory factor analysis and Rasch analysis, aiming at unidimensionality and fit to the Rasch model. Reliability was determined by Cronbach's coefficient-α and Person separation index. Longitudinal reliability was tested by differential item functioning in stable patient subgroups. Concurrent validity was examined in Norwegian (n = 101) and Swedish (n = 107) patients., Results: Exploratory factor analysis and Rasch analysis identified six items with poor psychometric properties. The 30 remaining items fitted the Rasch model and proved unidimensional, supported by appropriate item and person fit residuals and a nonsignificant χ(2) probability. Crohnbach's α-coefficient 0.93 and Person separation index 0.86 indicate high reliability. Longitudinal reliability was excellent. Correlation with Short Form-36 and Psychological General Well-Being Index scores was high. A shorter subscale comprising eight items also proved valid and reliable. Testing of AddiQoL-30 in this large patient cohort showed significantly worse scores with increasing age and in women compared with men but no difference between patients with isolated AD and those with concomitant diseases., Conclusion: The validation process resulted in a revised 30-item AddiQoL questionnaire and an eight-item AddiQoL short version with good psychometric properties and high reliability.