Association of early dietary fiber intake and mortality in septic patients with mechanical ventilation based on MIMIC IV 2.1 database: a cohort study

Abstract Background Whether early dietary fiber intake in septic patients is associated with a better clinical prognosis remains unclear, especially the time and the amount. Therefore, we assessed the association between early dietary fiber intake and clinical outcomes in septic patients by examining an extensive database. Methods We conducted a retrospective cohort study using data from the MIMIC IV 2.1 database, focusing on consecutive septic patients requiring mechanical ventilation in medical or mixed medical-surgical ICUs. We collected patient demographics and nutritional data. Dietary fiber amounts were calculated according to enteral nutrition instructions from manufacturers within the first 72 h after admission. After adjusting for covariates, we employed restricted cubic spline (RCS) regression to investigate the relationship between fiber intake (FI) and 28-day mortality. Patients were categorized into three groups based on their fiber index (FI) within 72 h of admission: low fiber index (LFI) group when FI was < 3 g/(%), medium fiber index (MFI) group when FI ranged from 3 to 35 g(%), and high fiber index (HFI) group when FI ≥ 35 g(%). Univariate and multivariate Cox proportional hazards regression models were utilized to assess the association between early FI and 28-day mortality. We ultimately employed Kaplan–Meier (KM) curves and log-rank test visually represent the association between FI and 90-day mortality. The second outcomes include ICU-acquired infections and the hospital and ICU death, length of hospital and ICU stay, and length of mechanical ventilation. Results Among 1057 subjects, 562 (53.2%) were male, with a median age of 64.8 years (IQR 53.4–75.2). We observed a J-shaped relationship between FI and 28-day mortality. The MFI group exhibited the lowest 28-day mortality [adjusted HR 0.64 (0.45–0.91), p = 0.013] and the lowest rate of hospital mortality [adjusted OR 0.60 (0.39–0.93), p = 0.022], with no statistically significant differences noted in the HFI group when compared to the LFI group. Similar patterns were observed for 60-day and 90-day mortality. However, no statistically significant differences were observed in other secondary outcomes after adjusting for covariates. Conclusion Early medium fiber index intake improved 28-day mortality and lower hospital mortality in septic M/SICU patients on mechanical ventilation.