Dynamic Association Between Mean Arterial Pressure and 28-Day Mortality in Critically Ill Patients with Systemic Lupus Erythematosus: A Multicenter Retrospective Cohort Study

Objectives Most studies on blood pressure management in critically ill patients focus solely on static thresholds and neglect temporal exposure patterns. We systematically investigated the associations between mean arterial pressure exposure and 28-day mortality from both intensity and temporal dimensions in critically ill patients with systemic lupus erythematosus. Methods In this retrospective cohort study, 1,362 critically ill SLE patients were analyzed from two databases: MIMIC-III-CareVue V1.4 (n = 195) and MIMIC-IV V3.1 (n = 1,167). Hourly MAP measurements were collected for 24 hours post-ICU admission. Generalized additive models with tensor product smooths were used for continuous MAP-time-mortality surface analysis. Time-trend analysis using GAM-smoothed odds ratio trajectories examined the temporal evolution of MAP-associated mortality risk across different MAP categories. Results Both cohorts revealed a U-shaped relationship between MAP and mortality. Three-dimensional surface analysis identified an optimal MAP range of 75–85 mmHg, with the lowest predicted mortality at 77.88 mmHg (5.21%) in MIMIC-III and 80.30 mmHg (4.13%) in MIMIC-IV. Prolonged exposure to MAP below 50 mmHg significantly increased mortality (OR 5.06–14.13, P < 0.001), with risk escalating by 8.39% per hour in the MIMIC-IV cohort (24-hour OR increase: 6.92-fold, P < 0.001). Similarly, sustained MAP above 110 mmHg conferred elevated risk (OR 2.43–6.32, P < 0.001). Within the protective range, patients maintaining MAP at 75–80 mmHg demonstrated the strongest protection (OR 0.32–0.37, P < 0.001). Conclusions Our study confirms a U-shaped relationship between MAP and outcomes in critically ill SLE patients, emphasizing that hemodynamic management should consider both intensity and duration. Prolonged MAP below 65 mmHg or above 95 mmHg should be avoided, with an optimal target of 75–85 mmHg during the first 24 hours of ICU admission.