AB1215 CLINICAL RISK PREDICTION MODEL OF THE LOWER GASTROINTESTINAL INVOLVEMENT OF SYSTEMIC SCLEROSIS
Authors: S. Xu, H. Huang, J. Zhou, Q. Wang, D. Xu, M. Li, X. Zeng
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Systemic Sclerosis (SSc) is a systemic autoimmune disease, and many organs could be involved, especially the lung and gastrointestinal tract. A significant majority of SSc patients had gastrointestinal manifestations, but it is difficult to find intestinal involvement and treatment in early stage, and also effective treatments are lacking, the prognosis is poor. Consequently, the early diagnosis of intestinal involvement in SSc and the timely initiation of treatment to mitigate disease progression present considerable challenges for both clinicians and patients <h3>Objectives:</h3> This study aims to identify independent relevant factors of lower gastrointestinal involvement in systemic sclerosis and develop a clinical risk prediction model for lower gastrointestinal involvement in SSc patients. <h3>Methods:</h3> Clinical characteristics and laboratory examination for patients were collected and compared. Statistical analyses were performed using SPSS 27.0 (SPSS Inc. Chicago, IL, USA) and R version 4.3.1. Logistic regression was employed to identify independent relevant factors. Factors excluded blood test results were re-selected and a Nomogram risk prediction model was developed by R. The receiver operating characteristic curve (ROC) and Hosmer-Lemeshow test were utilized. Internal validation of the model was carried out using the Bootstrap procedure, and a clinical decision curve analysis (DCA) was conducted to assess the model's clinical utility. <h3>Results:</h3> The SSc patients with lower gastrointestinal involvement admitted to Peking Union Medical College Hospital from December 2003 to December 2023 were enrolled as the observation group. Additionally, SSc patients without lower gastrointestinal involvement were randomly selected as control group after matching age and gender at a ratio of 1:3. The observation group comprised 42 patients, while the control group included 126 patients. The data about the patients were showed in Table 1 and 2. Patients in the observation group exhibited lower BMI, RBC, HB, ALB, PA, Ca, and C3 levels compared to the control group. Additionally, they were more likely to be associated with cardiomyopathy. The observation group also displayed higher CRP levels, longer disease duration, and a higher rate of positive ANA and anti-Ro-52 antibody. Surprisingly, few patients in the observation group(19.05% in the observation group while 36.51% in the control group) presented with joint pain symptoms. The logistic regression analysis, incorporating laboratory parameters and symptoms as independent variables, identified BMI, cardiomyopathy, joint pain, total protein (TP), and prealbumin (PA) as independent relevant factors for the lower gastrointestinal involvement of systemic sclerosis. Furthermore, cardiomyopathy, joint pain, ANA, and anti-Ro-52 were selected as independent predictors in the clinical prediction model processed by R. Based on literature review, a longer disease duration was included as a risk factor in the model. The variables of the prediction model are cardiomyopathy, joint pain, ANA, anti-Ro-52, and disease duration. A nomogram risk prediction model was developed based on the outcomes (Figure 1). A correction curve was developed to evaluate the model's degree of rectification (Figure 2). The Hosmer-Lemeshow test indicated good calibration (χ2 = 9.16, P = 0.4226). The ROC curve of this model is shown in Figure 3, with a calculated AUC value of 0.822 (95%CI: 0.738-0.810). Internal validation using the Bootstrap 1,000 times self-sampling method yielded an AUC of 0.822 (95%CI: 0.747-0.898) and a Brier value of 13.3 (95%CI: 10.1-16.6) (Figure 4). The clinical decision curve is presented in Figure 5, indicating that the threshold of 0.0300-0.8645 has the largest clinical net income. <h3>Conclusion:</h3> Our study suggested cardiomyopathy, joint pain, positive ANA and anti-Ro52 antibody, and disease duration were independent predictors of lower gastrointestinal involvement in systemic sclerosis. The clinical diagnostic model, based on these variables, demonstrates a certain degree of capability in predicting the risk of lower gastrointestinal involvement in systemic sclerosis.REFERENCES: NIL. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>