Mortality prediction in systemic lupus erythematosus patients with pulmonary infection

The impact of pulmonary infection (PI) on mortality of patients with systemic lupus erythematosus (SLE) has been established. Nevertheless, the effect of risk factors in mortality remains controversial. The objective of this study is to determine the risk factors of short-term mortality among SLE patients with PI.

The clinical data of 54 SLE patients with 59 episodes of PI who were hospitalized from January 2013 to May 2018 was retrospectively analyzed. Demographic data, clinical features, and outcomes were collected. Logistic regression analysis was carried out to determine the independent predictors of 60-day mortality during hospitalization. We used receiver operating characteristics (ROC) curves to verify the indices as mortality predictors in the study patients.

There were a total of 54 patients with 59 episodes of PI. There were 12 deaths during hospitalization. In multivariate analysis, 24-hour urinary protein (24h-PRO) (odds ratio [OR]: 2.713, 95% CI: 1.234-5.965, P = 0.013), peripheral lymphocyte count (OR: 0.066, 95% CI: 0.005-0.887, P = 0.040), and serum complement 3 level (C3) (OR: 0.097, 95% CI: 0.010-0.954, P = 0.045) were associated with mortality among our cohort of SLE patients with PI. ROC curve values were 0.818 for lymphocyte count (95% CI: 0.696-0.907, P = 0.001), 0.894 for 24h-PRO (95% CI: 0.786-0.959, P < 0.001) and 0.825 for C3 (95% CI: 0.704-0.912, P = 0.001). The cut-off value of lymphocytes, 24h-PRO and C3 were 0.53 × 10⁹ /L, 0.92 g and 0.52 g/L, respectively.

The presence of albuminuria, lymphopenia and low complement C3 levels were independent prognostic predictors of short-term mortality in SLE patients with PI.