Association of cumulative methylprednisolone dosages with mortality risk from pneumonia in connective tissue disease patients.

Corticosteroid is essential in the treatment regimen for connective tissue disease (CTD); however, its long-term use poses significant risks, including pulmonary infections. The relationship between cumulative corticosteroid doses and adverse pneumonia outcomes requires further investigation. This study aimed to explore the association between cumulative methylprednisolone dosages (CMD) and pneumonia mortality risks among CTD patients. We conducted a retrospective analysis of data from CTD patients treated with intravenous or oral corticosteroids across six academic hospitals over approximately five years in China. We evaluated follow-up outcomes at 30 and 90 days after the onset of pneumonia. Piecewise linear regression, Cox regression analysis, and survival analysis were employed to investigate the relationship between CMD and 30-day and 90-day mortality risks. Among 335 CTD patients with pneumonia, the mean CMD was 12 g. The 30-day and 90-day mortality rates were 25.07% and 29.55%, respectively. After adjusting for potential confounders, smooth curve fitting analysis revealed a specific nonlinear relationship between CMD and 30-day and 90-day mortality risks. Cox regression analysis indicated that the lowest pneumonia mortality risk occurred when CMD ranged from 11 to 24 g (30-day adjusted hazard ratio (aHR) 0.33, 95% CI 0.14-0.77; 90-day aHR 0.37, 95% CI 0.17-0.81). Patients in the 11-24 g CMD group demonstrated significantly lower cumulative hazard and death rates compared to both the low CMD (< 11 g) and high CMD (> 24 g) groups (P < 0.05). Furthermore, interaction testing suggested that CMD's negative impact on pneumonia mortality risks was more pronounced in community-acquired pneumonia (CAP) compared to hospital-acquired pneumonia (P for interaction < 0.05). CMD shows a distinct nonlinear relationship with 30-day and 90-day pneumonia mortality risks, with potentially lower risks observed within the 11-24 g CMD range. Moreover, the varying impact of CMD on CAP mortality risk warrants further consideration in clinical management strategies.