Analysis The Clinical Features And Prediction Model Of Primary Sjogren’s Syndrome With Interstitial Lung Disease

Research backgroundSjgren’s syndrome(SS)is a progressive systemic inflammatory autoimmune disease characterized by involvement of exocrine glands and extraglandular viscera with unknown causes.It is characterized by progressive infiltration of lymphocytes and plasma cells into target organs,which can involve all organs of the body and present symptoms of various systems.Primary Sjogren’s syndrome was first described by gougerot in 1926.The incidence rate is estimated to be 0.5%.Primary Sjgren’s Syndrome(pSS)is more common in clinic,and the incidence of female is higher.At present,in addition to lung biopsy,high resolution computed tomography(HRCT)and pulmonary function test(PFT)are the most commonly used noninvasive examinations in the diagnosis and evaluation of connective tissue disease-related lung disease(CTD-ILD).However,due to the radiation of HRCT,or due to the condition of hospital equipment,some patients can not be examined by HRCT.When pSS patients complicated with emphysema or pulmonary hypertension,the results of PFT will be confused,and it is impossible to accurately identify whether pSS patients complicated with ILD.In recent years,many experts and scholars have devoted themselves to the study of biomarkers for monitoring CTD-ILD.Many studies at home and abroad have shown that KL-6 can be used as a biomarker for early detection of connective tissue disease with interstitial lung disease.At present,KL-6 has been written into the guidelines for the diagnosis and treatment of drug-induced pneumonia and idiopathic interstitial pneumonia by Japanese health plan.Other studies have shown that KL-6 is more likely to be associated with ILD when the level of KL-6 in pSS patients increases,which can be used as a serological indicator to predict pSS patients with ILD.However,in clinical work,due to the limited laboratory equipment and high cost,it is difficult to detect KL-6,which seriously limits its clinical use.ObjectiveAnalyze the clinical characteristics and risk factors of primary Sjogren’s syndrome complicated with interstitial lung disease,construct the prediction model of pSS complicated with ILD,and evaluate the advantages and disadvantages of the model and KL-6 in predicting pSS complicated with ILD,so as to provide a reliable evaluation tool for clinicians to evaluate whether pSS patients complicated with ILD.MethodPatients with pSS admitted to the Department of Rheumatology and immunology and Department of respiratory medicine of the First Affliated Hospital of Zhengzhou University from January 2016 to December 2019 were collected.After strict inclusion and exclusion criteria,207 patients with pSS were included.Among them,120 patients complicated with interstitial lung disease were selected as the observation group,and 87 patients without interstitial lung disease were selected as the control group.The basic information,general laboratory results,autoantibody results,clinical symptoms and influencing factors were collected.SPSS 25.0 was used for statistical analysis.The S-W normal test was used to test whether the measurement data was in accordance with the normal state,and the mean± standard deviation(x±s)was used to describe the measurement data conforming to the normal distribution.The difference between the two groups was compared with the variance,and the variance was tested by t-test,and the variance was not all corrected t-test.The measurement data that do not conform to the normal distribution are represented by median(quartile)[M(P25,p75)],and the comparison of the differences between the two groups is tested by Mann Whitney U.The statistical data were expressed by composition ratio,and chi square test(χ2)was used to compare the differences between groups.The risk factors of pSS combined with ILD were analyzed by multivariate logistic regression,and the Odds ratio(OR)and 95%confidence interval(CI)were calculated.Then,the statistical variables in the comparison between the groups were corrected by bonferoni method.The correlation between the variables which still had statistical significance was evaluated by the point biserial correlation coefficient.The correlation coefficient was visualized by the R software corrplot package.The correlation coefficient was more than 0.5,and the correlation coefficient was considered to be medium or above correlation among variables.The logistic regression model was established by R software RMS package:the weight of the independent variables on the influence of the variables on the combination of ILD was calculated by the multivariate regression model,and the value was assigned to evaluate the possibility of the patients with pSS combined with ILD.The model was verified by 1000 random sampling calibration curves and the evaluation of consistency index(C-index).The model constructed by drawing receiver operator characteristic curve and KL-6 were used to evaluate the value of predicting the combined ILD in patients with pSS.The difference was statistically significant in P<0.05.Result1.There were 73 female cases(83.91%)and 14 male cases(16.09%)in pSS group,and 91 female cases(75.83%)and 29 male cases(24.17%)in pSS patients complicated with ILD group.There was no significant difference in gender composition between the two groups(P>0.05).The onset age of pSS patients complicated with ILD group was higher than that of PSS group(P<0.05).There was no significant difference in the course of disease between the two groups(P>0.05).2.The levels of complement C3、CRP、D-D and KL-6 in the patients with pSS patients complicated with ILD group was higher than that of the patients in the pSS group,and the albumin level was lower than that of the patients in the pSS group,the difference was statistically significant(all P<0.05).There was no significant difference in the levels of C4、ESR、PCT、IgG、IgA、IgM and globulin between the two groups(all P>0.05).The positive rates of anti SSA antibody and anti SSB antibody in the patients of pSS patients complicated with ILD group were lower than those in the pSS group(all P<0.05),but the differences of the other antibodies between the two groups were not statistically significant(all P>0.05)3.The incidence of cough and dyspnea in pSS patients complicated with ILD group was higher than that in pSS group(all P<0.05),but there was no significant difference in the incidence of fever,Raynaud phenomenon,morning stiffness,dry mouth and dry eyes between the two groups(all P>0.05).4.The levels of TLC%,FEV1%,MMEF75/25%,DLCOSB%in pSS patients with ILD were significantly lower than those in pSS patients(all P<0.05),but there was no significant difference in FVC%between the two groups(P>0.05).5.The most common HRCT sign of pSS with ILD was ground glass change in 68 cases(56.67%).6.In this study,the sensitivity of pSS combined with ILD was 77.2%,specificity 97.3%,area under curve was 0.936,95%confidence interval(CI)was(0.875-0.973)by combining age,complement C3,cough,D-dimer,anti SSA antibody and albumin index.The sensitivity,specificity,area under the curve and 95%confidence interval(CI)of KL-6 were 67.5%,96.7%,0.859 and(0.808-0.910)respectively.ConclusionCombined with age,complement C3,cough,D-dimer,anti SSA antibody and albumin,the predictive model was better than KL-6 in assessing the risk of PSS with ILD.