Ab1229 Monocyte HDL Ratio in Systemic Sclerosis Patients and Its Association With Choroidal Subfoveal Thickness – Case Control Study

Background: Systemic sclerosis (SSc) is characterized by immune dysregulation, vasculopathy and fibrosis. Fibroproliferative vasculopathy in small arteries and destructive vasculopathy in capillaries are the two unique features causing tissue ischemia and fibrosis. Monocytes/macrophages contribute to the pathogenesis of SSC by secreting TGF-β, a key fibrogenic cytokine. However, HDL prevents migration and recruitment of macrophages. According to recent studies, monocyte/HDL ratio (MHR) positively correlated with markers of acute inflammation, digital ulcers, skin fibrosis and atherosclerosis[1]. Hence MHR is postulated to serve as a surrogate marker of inflammation. In Post-mortem studies, choroidal arteries in SSc patients were grossly damaged with endothelial cell damage, basement membrane thickening and loss of pericytes[2]. We hypothesize that SSc patients will show alterations in choroidal thickness as a result of choroidal hypoperfusion, which may correlate with the MHR-measured burden of inflammation. Objectives: 1.To detect choroid abnormalities in SSc patients by measuring choroidal Subfoveal thickness (Sf CT) using Cirrus High-Definition Optical Coherence Tomography(HD OCT) and comparing the results with age- and gender-matched healthy controls. 2.To estimate and compare MHR between the two groups. 3.To correlate MHR with Sf CT in SSc patients. Methods: After obtaining ethical committee approval, this analytical case-control study was carried out in the Department of Rheumatology at a tertiary care centre in India between January and September 2023. A total of 25 SSc patients and an equal number of healthy age and sex-matched controls were recruited. Absolute monocyte count and HDL values were obtained from complete blood picture and fasting lipid profile. MHR was calculated for all the participants. Sf CT was measured from the external limit of Bruch's membrane to the innermost layer of the sclera at the subfoveal location by a single ophthalmologist. SSc patients who are older than 18 and fulfil the 2013 ACR/EULAR Classification criteria along with age- and sex-matched healthy individuals without a history of systemic or ocular disease were included. This study excluded individuals with diabetes mellitus, hypertension, age-related macular degeneration, cataracts, corneal opacities or past ocular surgery. The data was analyzed using means for continuous variables and T-test to compare the results between the two groups. Results: The study cohort has a 9:1 female-to-male ratio, a mean age of 38.2 years and a mean disease duration of 3.9 years.13 patients had diffuse cutaneous SSc, 11 had limited cutaneous SSc and 1 had sine scleroderma. 15 patients had early SSc (disease duration <3 years) and 10 had late SSc. SSc patients had a mean MHR of 17.58, a value higher than the control group's 10.73. Compared to controls (289 μm), the mean Sf CT in SSc patients (224 μm) is significantly lower. The T-test results confirmed a significant difference in Sf CT between the groups, with a significant p-value (0.005) and a substantial mean difference (-34.52). When comparing the MHR values between the two groups, there was a noticeable mean difference (6.85) and a significant p-value (0.005)(Table 1). Conclusion: Patients with SSc who exhibit elevated MHR have significantly reduced Sf CT. The aforementioned findings highlight the potential utility of Sf CT measurement and MHR as a simple, non-invasive strategies for determining the burden of inflammation in SSc patients. REFERENCES: [1] Kim HB et al. Associations of serum monocyte-to-high-density lipoprotein cholesterol ratio with digital ulcers and skin fibrosis in patients with systemic sclerosis. Scand J Rheumatol. 2021 May 4;50(3):231–8. [2] Farkas TG et al. The Choroidopathy of Progressive Systemic Sclerosis (Scleroderma). Am J Ophthalmol. 1972 Nov 1;74(5):875–86. Acknowledgements: NIL. Disclosure of Interests: None declared.