Background:Rheumatoid arthritis (RA) is a chronic inflammatory disease in which an abnormal body composition was reported to be highly prevalent. (1) Bioelectrical phase angle (PhA) is a measure of the relationship between electric resistance and reactance obtained via bioelectrical impedance analysis (BIA). (2) As an indicator of cellular health, PhA has been described as a predictor of worse clinical outcome and higher mortality in various conditions. (3) Since there is evidence that PhA is related to disease progression and prognosis when considering chronic inflammatory conditions, a lower PhA may also be considered an indicator of a worse prognosis in RA. (1)Objectives:To study the association between PhA, functional status and impact of disease in RA patients.Methods:Observational and cross-sectional study, including 53 patients with RA diagnosis according to the ACR/EULAR 2010 criteria. Each patient demographic data was recorded, and body composition, including PhA by BIA, was obtained. BIA was performed using Bodystat QuadScan 4000 equipment. Functional status and impact of disease were assessed using the Health Assessment Questionnaire (HAQ) and the Rheumatoid Arthritis Impact of Disease (RAID) scores, respectively. PhA was stratified by tertiles (lowest, middle and highest) to create groups of patients. Statistical analysis was performed using student’s t-test (IBM SPSS version 26) for comparisons between groups.Results:A total of 53 patients with RA (81.1% women) with an average age of 62.2 ± 10.2 years were assessed. Mean PhA was 5.8 ± 1.7 °. A PhA lower than 5.2 ° (lowest tertile) was recorded in 17 patients; A PhA ranging from 5.2 ° to 6.0 ° (middle tertile) was observed in 18 patients; A PhA greater than 6.0 ° (highest tertile) was seen in 18 patients. Mean HAQ score was 1.43 ± 0.61 in the lowest tertile, 0.85 ± 0.57 in the middle tertile and 0.67 ± 0.57 in the highest tertile. Mean RAID score was 5.86 ± 1.69 in the lowest tertile, 4.73 ± 2.05 in the middle tertile and 3.00 ± 1.94 in the highest tertile. The statistical analysis showed significant differences in both HAQ and RAID scores between the lowest and the highest tertiles (p=0.001 and p <0.001, respectively). Significant differences were also found between the lowest and the middle tertile for HAQ score (p=0.007) and between the middle and the highest tertile for RAID score (p=0.017).Conclusion:In our cohort a lower PhA was significantly associated with higher HAQ and RAID scores, indicating higher disease impact and higher disability in RA patients with lower PhA. These results support the hypothesis that PhA may be investigated as a possible indicator of disease prognosis in RA.References:[1]Pineda-Juárez JA, Lozada-Mellado M, Ogata-Medel M, Hinojosa-Azaola A, Santillán-Díaz C, Llorente L, et al. Body composition evaluated by body mass index and bioelectrical impedance vector analysis in women with rheumatoid arthritis. Nutrition. 2018;53:49–53.[2]Rinaldi S, Gilliland J, O’Connor C, Chesworth B, Madill J. Is phase angle an appropriate indicator of malnutrition in different disease states? A systematic review. Clin Nutr ESPEN. 2019;29:1–14.[3]Norman K, Stobäus N, Pirlich M, Bosy-Westphal A. Bioelectrical phase angle and impedance vector analysis - Clinical relevance and applicability of impedance parameters. Clin Nutr. 2012;31(6):854–61.Disclosure of Interests:None declared
Patterns of bioelectrical impedance vector distribution by body mass index and age: implications for body-composition analysis
