A Clinical Model For The Prediction Of Progressive Pulmonary Fibrosis Risk Within 1 Year In Patients With Rheumatoid Arthritis-associated Interstitial Lung Disease

Objective: Interstitial lung disease(ILD)is a serious extrasarticular manifestation of rheumatoid arthritis(RA).Some patients with rheumatoid arthritis-associated interstitial lung disease(RA-ILD)show progressive pulmonary fibrosis(PPF)even after treatment.The patients with PPF are similar to idiopathic pulmonary fibrosis in disease progression and risk of death,and the prognosis is very poor.Therefore,early identification of risk factors for the progression of pulmonary fibrosis and intervention to delay the progression of pulmonary fibrosis is of great significance to improve the prognosis of patients.The main purpose of this study was to study the risk factors of developing PPF within 1 year in patients diagnosed with RA-ILD and to develop a nomogram.Methods: A retrospective study was conducted in 145 RA-ILD patients diagnosed in the Affiliated Hospital of Qingdao University between January 2010 and October 2022 who met the inclusion criteria.Among them,106 patients and 39 patients were randomly assigned to the training group and the validation group respectively,and the inclusion indicators were statistically described.The included indicators were comprised of routine blood test,blood gas analysis,pulmonary function,imaging manifestations,and therapeutic drugs.The independent predictors of PPF in patients with RA-ILD within one year were determined by univariate and multivariate logistic regression analysis.Then a nomogram was established through these independent predictive variables.Calibration curve,Hosmer-Lemeshow test,receiver operating characteristic(ROC)curve and area under curve(AUC)and clinical decision curve were used to evaluate the predictive efficiency of the nomogram model for PPF in RA-ILD patients within one year.Finally,the stability of the constructed model was tested by internal validation using the patient data of the validation group.Results: The average age of 145 patients with RA-ILD who met the inclusion criteria was68.08±9.65 years.There were 62 male patients(42.76%)and 83 female patients(57.24%),and there were more female patients.High-resolution computed tomography(HRCT)showed reticular shadow,interlobular septal thickening,pleural thickening,ground glass shadow,nodules,honeycombing,bronchiectasis and other manifestations.The HRCT phenotypes of the lungs were mostly usual interstitial pneumonia(UIP)and nonspecific interstitial pneumonia(NSIP).A few cases presented with organizing pneumoni(OP).Among them,62(42.76%)patients with RA-ILD developed PPF within 1 year,including40(37.7%)in the training group and 22(56.41%)in the validation group.The PPF group had a higher proportion of patients with subpleural abnormalities(75% vs.48.48% in the training group,P<0.05),a higher visual fibrosis score(24.5 vs.15 in the training group,P<0.05),and a shorter duration of RA(P<0.05),and there was no significant difference in other included indicators.Logistic regression analysis showed that the duration of rheumatoid arthritis(RA),visual score of fibrosis and subpleural abnormality were independent risk factors for the occurrence of PPF within 1 year after diagnosis in patients with RA-ILD.A nomogram was constructed based on these independent risk factors.The AUC values of the training group and the verification group were 0.798 [95%confidence interval(CI): 0.713,0.882] and 0.822(95% CI: 0.678,0.967)respectively,indicating that the model had a good ability to distinguish.The clinical decision curve showed that the clinical benefit of PPF risk prediction model was greater when the risk threshold was between 0.06 and 0.71.Conclusion: According to the duration of RA,the visual score of fibrosis and the presence of subpleural abnormalities,the predictive model of PPF was drawn to provide reference for the clinical prediction of PPF in patients with RA-ILD within 1 year after diagnosis.