Elevated serum gamma-glutamyl transferase level as a predictor of mortality in patients with anti-MDA5 antibody-positive dermatomyositis

Background Gamma-glutamyl transferase (GGT) has been identified to correlate with systemic inflammation in autoimmune diseases, while the role of GGT in anti-melanoma differentiation-associated protein 5 antibody-positive dermatomyositis (MDA5 + DM) remains unknown. This study aimed to investigate the clinical and prognostic significance of serum GGT in MDA5 + DM patients. Methods Patients with MDA5 + DM admitted to the First Affiliated Hospital of Zhengzhou University between February 2019 and May 2023 were retrospectively analyzed. We compared the clinical features and prognosis between MDA5 + DM patients with elevated serum GGT levels and those with normal serum GGT levels. Cox regression analysis was performed to identify independent factors associated with mortality. Results A total of 299 MDA5 + DM patients were enrolled in this study. During the median follow-up time of 13.1(4.4–28.1) months, 153(51.2%) patients developed rapidly progressive interstitial lung disease (RP-ILD) and 75(25.1%) patients died within 6 months after disease onset. Serum GGT levels were significantly higher in the death group compared to the survival group [95(56–165) vs 45(26–90) U/L, p <0.001]. Based on the serum GGT levels at the time of diagnosis, we divided all the patients into two groups: normal GGT group (GGT ≤ 58U/L, n = 155) and elevated GGT group (GGT>58U/L, n = 144). Compared with the normal GGT group, patients in the elevated GGT group had increased incidences of skin ulcer and RP-ILD, higher levels of lactate dehydrogenase (LDH), Krebs Von den Lungen-6 (KL-6), ferritin and C-reactive protein (CRP), while lower levels of albumin and lymphocyte counts. Moreover, the Kaplan–Meier survival analysis demonstrated that the cumulative survival rate was significantly lower in the elevated GGT group than that in the normal GGT group (log-rank p  < 0.001). Multivariate Cox regression analysis revealed that RP-ILD, GGT>58U/L, LDH>345U/L, CRP>5mg/L and anti-Ro52 antibody positivity were independent risk factors of mortality in MDA5 + DM patients. Conclusions Elevated serum GGT level was an independent risk factor for mortality in MDA5 + DM patients. As a novel and readily available predictor, serum GGT level may help clinicians in guiding prognostic stratification and personalized treatment.