A Case-control Study On Serological Risk Factors Of Rheumatoid Arthritis Complicated With Interstitial Lung Disease

Objection: The purpose of this study is to explore the correlation between clinical serological indicators and the risk of rheumatoid arthritis complicated with interstitial lung disease.Methods: This study was a retrospective case-control study.From January 2010 to December 2019,the Department of Rheumatology and Immunology of the First Affiliated Hospital of China Medical University was collected from the Medical data intelligent platform with ICD-10v6.01 disease code.After screening by inclusion and exclusion criteria,387 patients in RA group were matched with RA-according to the principle of 1:1.The electronic medical records of RA patients with ILD and RA patients were screened,and the basic information,past history and serological indexes of clinical examination were extracted and the database was established.Excel 2016 software is used for data entry.When comparing two groups of data,independent sample T test or rank sum test is used for measurement data,and Chi-square test is used for counting data.Logistic regression was used to explore the risk factors of RA-ILD,and restricted cubic spline function(RCS)combined with Logistic regression was used to establish a model to explore the dose-response association between different serological indicators and RA-ILD.SPSS 23.0 and SAS 9.4 were used for statistical analysis,and the significance level was P<0.05(bilateral).Results: A total of 774 cases were included in this study,including 387 cases in case group(RA-ILD)and 387 cases in control group(RA).By comparing the abnormal rate of serological indexes between case group and control group,the indexes with significant difference were screened,and the multi-factor analysis was further carried out to explore the relationship between the biochemical indexes such as inflammation and immune factors and the risk of RA-ILD:(1)The level of ESR,CRP,Ig A,Ig G and IgM in RA-ILD group was significantly higher than that in RA group.(2)Multivariate analysis showed that the independent risk factors of ILD in RA patients were anti-CCP positive(OR=1.48,95%CI: 1.05-2.07,P<0.001),CRP>8mg/L(OR=1.51,95% CI:1.06-2.15,P=0.024)and IgM>2.50g/L(OR=3.94,95%CI: 2.19-7.10,P<0.001),smoking was also an independent risk factor of RA-ILD(OR=5.18,95% CI: 2.87-9.34,P=0.024).(3)The analysis of dose-response association showed that there was a significant nonlinear dose-response association between serum CRP,IgM levels and the risk of RA-ILD(CRP: Pnon-Lin-association < 0.001,IgM: Pnon-Lin-association = 0.0097).Conclusion: Our study found that CRP and IgM levels in RA patients are related to the risk of RA-ILD.In addition,anti-CCP antibody positive and smoking are risk factors of RA-ILD.Based on the research conclusion,it is suggested to pay close attention to RA patients with high CRP and IgM levels or positive anti-CCP antibodies while actively diagnosing and treating RA,and to monitor them with HRCT to assess the risk of ILD and give appropriate treatment measures as soon as possible.