AB0902 BONE HEALTH IN PATIENTS WITH JUVENILE ONSET DERMATOMYOSITIS ASSESSED AFTER LONG-TERM FOLLOW-UP; A CASE CONTROL STUDY. (2nd June 2020) - Marstein, H.
Abstract : Background: Patients with juvenile dermatomyositis (JDM) are at risk of developing low bone mineral density (BMD) and not reach peak bone mass, mainly due to prednisolone (pred) treatment [1], making them prone to osteoporotic fractures later in life Objectives: To compare BMD in longterm JDM patients (Pts) with that of controls (Ctr); and in Pts explore how disease variables affect BMD. Methods: Pts (n=59) were clinically examined median 16.8y (range 6.6 - 27.0 y) after disease onset and compared 1:1 with age/sex matched Ctr. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD and Z-scores in whole body (WB), lumbar spine at L2-L4 (spine). In those ≥ 20y; also proximal (PR) and distal 1/3 radius (DR), and total hip were examined. Pred at follow up was reported, and cumulative dose calculated. Bone remodeling factors: C-terminal telopeptide (CTX), amino-terminal propeptide (P1NP) and 25(OH)Vitamin D (VitD), were measured in serum. Results: BMD WB was lower in Pts than Ctr, and both WB and spine BMD and Z scores were lower in Pts than Ctr <20 years (Tbl 1). DR BMD and Z-score were both lower in Pts ≥20y. Serum analysis showed lower VitD was lower in Pts than Ctr. In Pts ≥ 20y Vit D was lower and eSR was higher compared to Ctr. In Pts ≥ 20y: moderate negative associations were found between both BMD WB and spine, and pred use at follow up (R`s = -0.43), and between BMD PR and VitD (R= -0.34). There was a positive moderate association between Z-score PR and CTX (-0.45) not found in Ctr, and between Z-score total hip and cumulative pred dose (R = 0.38). All p <0.05. In Pts <20y moderate negative associations were found between Z-score for spine and months of pred use and cumulative pred doses (R`s = -0.40 and -0.48, p<0.05). Other associations found in Pts <20y were also found in respective Ctr. Conclusion: We found that Pts bone health was affected differently in young and adult JDM-Pts. Association analysis between BMD, Z-scores and medication and/or bone remodeling factors were not conclusive. We will perform linear regression analysis to determine if and how BMDs and Z-scores are dependent on pred use, time and doses, and factors important for bone remodeling. References: [1]Stewart, W.A., et al., Bone mineral density in juvenile dermatomyositis: assessment using dual x-ray absorptiometry. Arthritis Rheum, 2003. 48(8): p. 2294-8. Words: 3555 Disclosure of Interests: None declared