# Pre-treatment serum albumin predicts relapse in idiopathic inflammatory myopathies: a retrospective cohort study with cytokine profiling

## TL;DR

Low pre-treatment serum albumin levels predict relapse in inflammatory muscle diseases and reflect ongoing inflammation.

## Contribution

Identifies serum albumin as an independent predictor of relapse and links it to elevated inflammatory cytokines.

## Key findings

- Low pre-treatment albumin levels independently predict overall and ILD relapse in IIM patients.
- 14 cytokines, including IL-6 and MCP-1, are significantly elevated in patients with low albumin levels.
- The V-neck sign strongly predicts ILD relapse in anti-ARS-positive patients.

## Abstract

To identify predictors of relapse in patients with idiopathic inflammatory myopathies (IIMs) and investigate the biological mechanisms underlying these associations using cytokine profiling.

We conducted a retrospective study of 99 patients who achieved remission after initial treatment for IIMs or myositis-specific antibody-positive interstitial lung disease at Nagasaki University Hospital. Among 197 diagnosed patients, we included those who achieved clinical improvement and were followed up for ≥3 months, excluding early deaths and those with insufficient follow-up. Relapse was defined as disease worsening requiring treatment intensification. Risk factors were analyzed using the Cox regression analysis. Serum cytokine profiles were compared between patients with low and high pre-treatment albumin levels.

Forty-one patients (41%) relapsed. Multivariate analysis revealed that pretreatment albumin level remained the only independent predictor of overall relapse (HR, 0.60; 95% CI: 0.40–0.92, P = 0.019). For ILD relapse, both albumin (HR: 0.51, 95% CI: 0.30–0.88, P = 0.015) and female sex (HR: 0.70, 95% CI: 0.52–0.95, P = 0.022) remained independent predictors. In antibody-specific analyses, the V-neck sign strongly predicted ILD relapse in anti-ARS-positive patients (HR, 5.07; 95% CI: 1.64–15.75, P = 0.006). After false discovery rate correction, 14 cytokines remained significantly elevated in patients with low albumin levels, including IL-6 (7.5-fold, q < 0.001), IP-10 (5.3-fold, q < 0.001) and MCP-1 (2.5-fold, q < 0.001).

Pretreatment albumin levels independently predict relapse in IIMs, and cytokine profiling demonstrates that low albumin levels reflect active systemic inflammation. These findings support the use of albumin as a practical biomarker for risk stratification in clinical practice.