AB1042 ASSESSMENT OF BONE MINERAL DENSITY AND FREQUENCY FRACTURES PERIPHERAL SKELETON BONES IN PATIENTS WITH ALKAPTONURIA
Authors: A. Kuzin, A. Smirnov, E. Zaytseva, D. Kudinskiy, L. Blank, E. Dolzhenkova, N. Politova
Journal: Annals of the Rheumatic Diseases (2020)

Background: Objectives: To assess the bone mineral density (BMD) of the skeleton using the Hologic Discovery A DXA, determine the frequency of low-energy skeletal bone fractures among adult patients with alkaptonuria (AKU), and identibjectivefy factors that affect the occurrence of fractures. Methods: AKU is a rare genetic disease (1 case per 250,000) which occur to severe damage to the spine and large joints. Serious problem in this category of patients is a decrease in BMD. The study included 40 patients with a reliable diagnosis of AKU (23 men and 17 women) aged from 33 to 78 years (mean 60.32±9.1). Densitometry of the lumbar spine was performed in 40 patients; of the forearm bones in 34 patients; of the proximal femur in 32 patients (8 patients were not examined due to bilateral hip joint replacement). Results: Normal values of spinal BMD were found in 26 patients (65%), osteopenia – in 12 (30%) and osteoporosis – in 2 (5%) patients. In the proximal parts of the femur, osteoporosis was detected in 12 patients (30%), osteopenia in 13 (32.5%), and normal in 7 (17.5%) patients. In the bones of the forearm, osteoporosis was found in 22 patients (55%), osteopenia – in 8 (20%), and norm – in 4 (10%) patients. The BMD values (g / cm 2 ) in the group were as follows: Table 2. Disease and treatment characteristics of 2 discrete phenotypes (Systemic and Chronic articular) Systemic form Chronic articular form Total Patients (n) 10 6 16 Duration of follow-up (years), median (range) 13 (3-24) 14 (1-14) 14 (1-24) Duration of disease prior to bDMARDs (months) 7.5 (2-120) 21 (3-36) 10.5 (2-120) Number of cDMARDs prior to bDMARDs 2 (1-2) 1 (1-4) 2 (1-4) Patients on concomittant cDMARDs, n (n/N%) 10 (100%) 6 (100%) 16 (100%) Type of 1 st bDMARD (n) 3 TCZ, 2 anti-TNFa, 4 Anakinra, 1 Canakinumab 4 anti-TNFa, 2 TCZ Patients on bDMARD at the end of follow-up (n/N%) 6 (60%) 6 (100%) 12 (75%) Time to steroids discontinuation after bDMARD initiation (months) 7.5 (2-22) 4.5 (3-36) 6.5 (2-36) N Mean Percentiles 25th 75th BMD L1-L4 40 1,06 0,88 1,25 BMD Prox.Femur 32 0,56 0,61 0,81 BMD Forearm 34 0,48 0,43 0,54 Peripheral bone fractures were diagnosed in 15 (32.6%) patients – 9 men and 6 women; 25 (62.5%) patients had no fractures. For the first time, fractures were reported in patients aged from 33 to 69 years (mean 55.9±9.5). The localization of fractures was as follows: femur – in 8 patients (20%), forearm – in 6 (15%), shin bones – in 1 (2.5%) patients. Despite lower BMD rates in women, there were no significant differences in the frequency of fractures depending on sex. Correlation analysis (for Spearman) showed the relationship of fractures with age (r= -0.31, p&lt;0.05), femur BMD in general (r= -0.53, p&lt;0.01) and forearm BMD (r= -0.44, p&lt;0.01). Conclusion: There is a high incidence of osteoporosis, mainly in the proximal femur and forearm in patients of the older age group with AKU. In the lumbar spine (due to the development of calcification of the intervertebral discs and ligamentous apparatus), osteoporosis is rarely detected, but the frequency of osteopenia is quite high. 32.6% patients had a history of skeletal bone fractures, and the sex of the patients did not affect the risk of fractures. The occurrence of fractures in patients with AKU is associated with low BMD values of the proximal femur. Disclosure of Interests: None declared