Development and external validation of a model for lung transplantation-free survival prediction of primary Sjögren syndrome-associated interstitial lung disease: a prospective cohort study.

BACKGROUND

Primary Sjögren syndrome-associated interstitial lung disease (pSS-ILD) patients have a worse prognosis than pSS patients without pulmonary involvement. This study aims to establish a prediction nomogram for early prediction of lung transplantation (LTx)-free survival in pSS-ILD patients.

METHODS

The training cohort comprised 260 patients from China-Japan Friendship Hospital between 1 January 2016 and 30 June 2022, while the external validation cohort consisted of 135 patients from Beijing Chaoyang Hospital between 1 January 2007 and 31 December 2012. Univariable Cox regression analysis and least absolute shrinkage and selection operator were employed for variable selection, and a nomogram model was developed to predict the 1-, 3- and 5-year LTx-free survival. Discrimination and calibration of the nomogram were assessed using the concordance index (C-index), area under the curve, calibration curve and decision curve analysis.

RESULTS

Multivariable Cox regression demonstrated that elevated age, oxygenation index, carbohydrate antigen 125 and fibrosis score were independent risk factors for LTx-free survival in pSS-ILD patients. The C-index values for the training and validation cohorts were 0.812 and 0.809, respectively. The 1-, 3- and 5-year AUC values for the training cohort were 0.781, 0.874 and 0.909, respectively, while those for the validation cohort were 0.793, 0.826 and 0.863. The bias-corrected curve was close to the ideal curve and revealed a strong consistency between predicted and observed outcomes.

CONCLUSIONS

We developed a nomogram capable of predicting the LTx-free survival probability at 1, 3 and 5 years in pSS-ILD patients. This model has the potential to be a useful tool for prediction of death or LTx in pSS-ILD.