Disease-related readmission in anti-SRP-positive immune-mediated necrotizing myopathy: Incidence and exploratory associated factors in a retrospective cohort study
Beibei Cui, Hongjiang Liu, Ruiting Liu, Ziqi Li, Huijiao Chen, Geng Yin, Qibing XieBackground
Anti-signal recognition particle (anti-SRP)-positive immune-mediated necrotizing myopathy (IMNM) is a severe subtype of idiopathic inflammatory myopathy, but its long-term prognosis and determinants of adverse outcomes remain insufficiently defined. Because relapse is difficult to ascertain consistently in retrospective studies, IMNM-related readmission may serve as a pragmatic outcome for evaluating subsequent disease course.
Objectives
To estimate the incidence rate of IMNM-related readmission after first discharge and to explore factors associated with readmission in patients with anti-SRP-positive IMNM.
Design
A single-center retrospective cohort study.
Methods
We included consecutively hospitalized adults with anti-SRP-positive IMNM at West China Hospital between January 2010 and June 2025. Follow-up began at first discharge. The outcome was readmission attributed to IMNM disease activity. The overall incidence rate was calculated per 100 person-years. Stratified incidence analyses were performed according to baseline variables, and factors associated with readmission were explored using LASSO-penalized Cox regression and univariable Cox regression.
Results
Among 131 included patients, 27 experienced IMNM-related readmission during follow-up. The median follow-up was 2.64 years, with a total of 398.53 person-years. The overall incidence rate of IMNM-related readmission was 6.77 per 100 person-years (95% CI, 4.46–9.86). Patients with higher De Ritis ratio (DRR, AST/ALT) had a higher readmission incidence rate than those with lower DRR [9.75 vs 3.28 per 100 person-years; incidence rate ratio (IRR) 2.98, 95% CI 1.24–7.16]. In exploratory univariable Cox regression, DRR was associated with increased readmission risk (HR 3.26, 95% CI 1.49–7.13; P = 0.003).
Conclusion
IMNM-related readmission occurred in approximately one-fifth of patients with anti-SRP-positive IMNM during follow-up. Higher DRR was associated with a higher rate of IMNM-related readmission in exploratory analyses. Further prospective studies are needed to clarify the prognostic relevance of DRR and to better characterize the long-term disease course of anti-SRP-positive IMNM.