ABS0354 COMPARATIVE EVALUATION OF BONE MASS AND BODY COMPOSITION IN PATIENTS WITH EROSIVE HAND OSTEOARTHRITIS AND PERIPHERAL PSORIATIC ARTHRITIS

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Background: The EULAR recommendations suggest that Erosive Osteoarthritis (EOA) is a rarer and more severe subtype of hand osteoarthritis, characterized by more joint destruction and disability. EOA may mimic Peripheral Psoriatic Arthritis (PsA) as both affect the proximal and distal interphalangeal joints. These two conditions may be challenging to differentiate in clinical practice and share common risk factors such as obesity. There are no specific studies on body composition in patients with EOA versus PsA. Objectives: To describe and compare body composition parameters using dual-energy x-ray absorptiometry (DXA) between participants with EOA and PsA. Methods: This is a single-center cross-sectional study conducted at the Hospital das Clínicas, University of São Paulo, São Paulo, Brazil, from May to October 2024. Participants classified with EOA and peripheral PsA involving interphalangeal joints were included, according to the classification criteria of the American College of Rheumatology (ACR) for hand osteoarthritis (1999) and the Classification Criteria for Psoriatic Arthritis (CASPAR) (2006), respectively. All participants were required to have at least two erosions located in the 2nd or 3rd proximal or distal interphalangeal joints of the dominant hand on x-ray. Data were collected through interviews, physical exams and electronic medical record review. Specific disease activity metrics and functional capacity assessment using the Health Assessment Questionnaire (HAQ) were registered. Bone mass and body composition parameters were obtained using the GE Lunar DXA device and included bone mineral density (BMD), T-score, Z-score, trabecular bone score (TBS), total fat (in kilograms and percentage), fat mass index (FMI – total fat kg/m²), visceral adipose tissue (VAT – in cm³ and grams), total lean mass (in Kg), and appendicular lean mass index (ALMI – kg/m²). Results: We evaluated 178 patients with Psoriatic Arthritis (PsA) and 38 patients with Erosive Osteoarthritis (EOA). Applying inclusion and exclusion criteria, 20 PsA participants and 17 EOA participants were included in the study. The groups had similar demographic characteristics, with a mean age of 65.9 (SD ± 7.9) years in the PsA group and 71.1 (SD ± 9.3) years in the EOA group ( p = 0.074). The majority of participants were female, 65% in the PsA group and 88% in the EOA group ( p = 0.137). The mean body mass index (BMI, Kg/m 2 ) was also similar between the groups: 27.9 (SD ± 5.1) in the PsA group and 29.3 (SD ± 4.2) in the EOA group ( p = 0.391). In the assessment of body composition (Table 1), there was a trend of a higher percentage of body fat in the EOA group (44% ± 6) compared to the PsA group (40% ± 7; p = 0.055), and a lower total lean mass in the EOA group (38 Kg ± 5) compared to the PsA group (42 Kg ± 9; p = 0.097). Regarding bone mass, PsA participants had lower total hip BMD (T-score -0,9 ± 0.8 vs -0.3 ± 0.9, p = 0.045; Z-score 0.0 ± 0.6 vs 0.9 ± 1.0, p = 0.002) compared to EOA patients. In the PsA group, no positive correlations were found between clinical data, imaging, bone mass and body composition). However, in the EOA group, the presence of ankylosis on hand X-rays was positively correlated with lumbar spine T-score (r = 0.74; p = 0.001), and Z-score (r = 0.59; p = 0.012). Subgroup analyses were performed based on metrics of disease activity, with the PsA group divided by DAPSA ≤ 14 (n = 10) and DAPSA ≥ 14 (n = 10), while the EOA group was divided by AUSCAN < 5.9 (n = 9) and AUSCAN > 5.9 (n = 8). Participants with higher AUSCAN had higher VAT volume (1701 cm³ ± 381 vs. 1202 cm³ ± 445; p = 0.033) and higher VAT mass (1605 g ± 360 vs. 1134 g ± 419; p = 0.033) compared to participants with lower AUSCAN. These same participants with higher AUSCAN also had in the lumbar spine higher BMD (1.232 g/cm³ ± 0.082 vs. 1.063 g/cm³ ± 0.194; p = 0.037), T-score (0.5 ± 0.5 vs. -1.0 ± 1.6; p = 0.021), and Z-score (1.9 ± 0.4 vs. 0.1 ± 1.4; p = 0.004). Furthermore, participants with higher AUSCAN showed greater functional impairment, with HAQ scores of 1.36 ± 0.66 compared to 0.57 ± 0.37 in the lower AUSCAN group ( p = 0.007). Conclusion: In this study, participants with EOA and PsA exhibited similar body composition, with a trend of higher body fat and lower lean mass in the EOA group. It was observed that a higher volume and mass of visceral adipose tissue correlated with worse pain and functional outcomes in participants with EOA. REFERENCES: [1] Bijlsma JW, et al. Ann Rheum Dis. 2018;77(4):377-386. doi:10.1136/annrheumdis-2017-212416. [2] Favero M, et al. Nat Rev Rheumatol. 2022 Mar;18(3):171-183. [3] Eder L, et al. J Rheumatol. 2017;44(4):437-443. [4] Ferraz, M. B., Oliveira. The Journal of Rheumatology, 1990; 17(6), 813-817. [5] Altman R, et al. Arthritis & Rheumatism, 1990;33(11):1601-1610. [6] Bellamy N, et al. Osteoarthritis Cartilage. 2002;10(11):855-862. doi:10.1053/joca.2002.0814. [7] Taylor W, Gladman D, Helliwell P, et al. Arthritis Rheum. 2006;54(8):2665-2673. doi:10.1002/art.21972. [8] Schoels MM et al. Annals of the Rheumatic Diseases, 2016;75(3):471-474. [9] Coates LC, Helliwell PS. Arthritis Care Res (Hoboken). 2010 Jul;62(7):965-9. doi: 10.1002/acr.20155. [10] Schuch NJ, et al, Archives of Osteoporosis. 2022;17(1):96. doi:10.1007/s11657-022-01116-3. Table 1 Comparison of APs (n=20) and OAE (n=17) patients regarding body composition parameters by DXA .Body Composition VariablesAPs (n=20)OAE (n=17)p valueFat, Kg (SD)28 ± 830 ± 60.528Fat, % (SD)40 ± 744 ± 60.055Visceral adipose tissue - VAT cm³ (SD)1702 ± 7991420 ± 4790.224Visceral adipose tissue - VAT g (SD)1608 ± 7541340 ± 4510.220Fat mass index - FMI kg/m² (SD)11.4 ± 3.612.3 ± 3.20.476Lean mass, kg (SD)42 ± 938 ± 50.097Appendicular lean mass index ALMI kg/m² (SD)7.1 ± 1.36.9 ± 0.80.538 Acknowledgements: NIL . Disclosure of Interests: None declared . © The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.

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