Abstract:Objective To explore the influencing factors of poor prognosis in patients with primary Sj?gren's syndrome (pSS) complicated with interstitial lung disease (ILD), and to construct and validate an early warning model.Methods A total of 243 patients with pSS complicated with ILD admitted to Kailuan General Hospital from March 2019 to March 2024 were retrospectively selected. According to the 8:2 allocation rule based on the randomization principle, they were divided into the training set (194 cases) and the validation set (49 cases). All patients were followed up for at least 1 year, and the prognosis was observed based on the occurrence of disease progression or death. Relevant clinical data of patients were collected for univariate analysis. Multivariate stepwise Logistic regression model was used to analyze the influencing factors of poor prognosis in patients with pSS complicated with ILD, based on which a nomogram early warning model was constructed. Receiver operating characteristic (ROC) curve was plotted to validate the early warning model.Results Among the 243 patients, 22 cases died and 62 cases had disease progression, with a total incidence of poor prognosis of 34.57% (84/243), including 66 cases of poor prognosis in the training set and 18 cases in the validation set. Compared with the good prognosis group, the poor prognosis group had significantly higher age, carbohydrate antigen 19-9 (CA19-9) level, Krebs von den Lungen-6 (KL-6) level, lactate dehydrogenase (LDH) level, ferritin level, hypoproteinemia rate and high-resolution computed tomography (HRCT) honeycomb shadow rate, while significantly lower forced vital capacity as a percentage of predicted value (FVC%pred) level, carbon monoxide diffusion capacity as a percentage of predicted value (DLCO%pred) level and 25-hydroxyvitamin D [25(OH)D] level (all P < 0.05). The results of multivariate stepwise Logistic regression analysis showed that advanced age [O^R = 1.184 (95% CI: 1.073, 1.306) ], low DLCO%pred level [O^R = 0.901 (95% CI: 0.856, 0.950) ], high KL-6 level [O^R = 1.009 (95% CI: 1.004, 1.015) ], low 25(OH)D level [O^R = 0.795 (95% CI: 0.710, 0.890) ], hypoproteinemia [O^R = 4.751 (95% CI: 1.451, 15.555) ] and HRCT honeycomb shadow [O^R = 23.963 (95% CI: 5.714, 100.494) ] were all risk factors for poor prognosis in these patients (all P < 0.05). The C-index of the nomogram constructed based on the results of multivariate stepwise Logistic regression analysis was 0.842, and the calibration curve was close to the ideal curve (P < 0.05). The area under the ROC curve (AUC) of the training set was 0.876, with a specificity of 0.836 and a sensitivity of 0.803; the AUC of the validation set was 0.865, with a specificity of 0.811 and a sensitivity of 0.759.Conclusion The early warning model constructed based on advanced age, low DLCO%pred level, high KL-6 level, low 25(OH)D level, hypoproteinemia and HRCT honeycomb shadow can effectively predict the prognosis of patients with pSS complicated with ILD.