Clinical Characteristics And Related Risk Factors For Rheumatoid Arthritis-Associated Interstitial Lung Disease

Objective:This study aims to explore the clinical characteristics and risk factors of rheumatoid arthritis(RA)-associated interstitial lung disease(ILD),thereby improving the prognosis of RA-ILD patients.Methods:A prospective cohort study was conducted on patients with rheumatoid arthritis based on the China rheumatic data center.Patients with RA diagnosed and treated in our department from November 2015 to August 2021 were divided into study group(RA-ILD group)and control group(RA group)according to the presence or absence of ILD(Interstitial lung disease,ILD).The clinical data of the two groups were analyzed and compared to explore the clinical characteristics and risk factors of RA-ILD.Then the patients with RA-ILD were followed up to March 2022.According to the changes of ILD during the follow-up,the patients were divided into two groups: ILD group and ILD group,to explore the influencing factors of interstitial lung disease in RA-ILD patients.The differences in general conditions,clinical manifestations,laboratory tests,disease activity,and treatment between the two groups were compared,and the clinical characteristics and related factors of RA-ILD were explored.Results:Part I:1.A total of 1554 patients with RA were included in the study.There were 97 patients in the study group(RA-ILD group)and 1457 patients in the control group(RA group).The proportion of male(36.0%)and the proportion of smoking history(24.7%)in the study group were higher than those in the control group(24.6%,12.1%)(P < 0.05).The onset age of RA in the study group was 57.92±12.66 years,higher than that in the control group(48.70±13.61 years)(P < 0.001).2.The positive rates of RF and anti-CCP in the study group were 88.7% and 97.9%,with no significant difference compared with the control group(P > 0.05),but the quantitative detection values of RF and anti-CCP in the study group were higher than those in the control group(P < 0.05).3.93(92.8%)patients in the study group were moderately/highly active in CDAI score,which was higher than that in the control group(85.4%)(P=0.034).4.67(67%)patients in the study group had no ILD related symptoms at the time of treatment,and most of their patterns of lung involvement on HRCT were UIP(64.1%).5.Logistic multivariate analysis showed that RA patients with RA onset age > 49.82 years old,high CDAI score,tumor,diabetes,cardio-cerebrovascular disease,osteoporosis and smoking were more likely to develop ILD.Part II:1.A total of 51 RA-ILD patients were followed up from 1 month to 72 months,28 patients reached the standard of ILD,and 23 patients did not reach the standard.The number of patients complicated with osteoporosis(43.5%)in ILDunreached group was higher than that in the ILD-compliant group(14.3%)(P < 0.05).2.There was no significant difference between the two groups of the level of KL-6 in the Baseline(P > 0.05),but the serum KL-6 level in ILD non-compliant group was 567.12(327.28,925.78)U/ m L after follow-up,which was higher than that in the ILDcompliant group 279.79(236.82,530.87)U/ m L(P=0.003).3.FVC/predicted% of the patients in the ILD-compliant group at baseline(81.16%±16.28%)were higher than those in ILD non-compliant group(67.63%±11.08%),and the level of FEV1/predicted%(87.41%±17.12%)were also higher than those in ILD non-compliant group(75.67%±15.56%).4.During the follow-up,there were 12 cases of infection incident and 2 deaths in the ILD non-compliant group,while 3 cases of infection incident and 1death occurred in the ILD-compliant group.5.Logistic multivariate analysis showed that the RA-ILD patients with osteoporosis were more difficult to relieve(OR: 52.312,95%CI: 2.152-1271.836,P=0.018),and RA-ILD patients with FVC/predicted %>75.15 in baseline were more likely to reach the standard(OR: 0.047,95%CI: 0.004-0.494,P=0.011).Conclusion:The onset age of most RA-ILD patients is older and often complicated with more diseases(diabetes,cardiovascular and cerebrovascular diseases,osteoporosis,etc.).The onset of RA-ILD is insidious with high disease activity of arthritis,and UIP is the frequent radiological pattern observed in RA-ILD.In this study,Osteoporosis is an independent risk factor for patients with RA-ILD to reach the standard of ILD,and FVC/predicted%>75.15% at baseline is a protective factor for the prognosis of patients with RA-ILD.Clinicians should be vigilant in the identification and evaluation of ILD,monitor the condition during follow-up,and achieve standard treatment as far as possible.