The effect of long-term traditional Chinese medicine treatment on extra-articular lesions of rheumatoid arthritis patients based on propensity score matching: A retrospective cohort studyKey messages

Objective: To explore the efficacy of long-term traditional Chinese medicine (TCM) treatment on the occurrence of extra-articular lesions in rheumatoid arthritis (RA) patients. Methods: Our retrospective cohort study included patients diagnosed with RA between January 2018 to December 2019. Patients were divided into TCM treatment group and control group according to whether they received TCM treatment for more than three months. Propensity score matching (PSM) was used to balance covariates between groups. The occurrence time of extra-articular lesions, including interstitial lung disease, Sjögren's syndrome, and anemia, was calculated for both groups after PSM. Additionally, clinical indicators that may affect the occurrence of extra-articular lesions in RA were included in Cox multivariate regression analysis to explore prognostic factors related to RA. Results: A total of 883 RA patients were initially included in our study, with 481 in the TCM treatment group and 279 in the control group. TCM treatment improved all clinical indicators of RA patients, and there was a higher degree of support, confidence, and lift between TCM treatment and the improvement of clinical indicators. There was no significant difference in the rate of extra-articular lesions occurrence between the two groups. After PSM, the median occurrence time of interstitial lung disease, Sjögren's syndrome and anemia in the TCM treatment group were 30.767, 21.370 and 31.970 months, respectively. While in the control group, it was 15.911, 14.667 and 11.825 months, respectively. Cox multivariate regression analysis indicated that TCM treatment was a protective factor for the occurrence of extra-articular lesions in RA, while abnormally high level of IgG was an independent factor for interstitial lung disease and C4 was an independent factor for Sjögren's syndrome. Moreover, a longer duration of TCM usage was associated with a later occurrence of extra-articular lesions. Conclusion: Long-term TCM treatment not only positively affects the occurrence time of extra-articular lesions in RA patients, but also helps reduce the risk of extra-articular lesions occurrence. TCM can be applied flexibly throughout the treatment process for RA patients.