Association of serum phosphate and changes in serum phosphate with 28-day mortality in septic shock from MIMIC-IV database

Predicting 72-Hour Fatality in Severe Hyperphosphatemia: A Comparative Analysis of Multivariate Logistic Regression and Machine Learning Models in a Single-Center Study

BACKGROUND

Hyperphosphatemia is associated with several serious diseases, including chronic kidney disease, tumor lysis syndrome (TLS), rhabdomyolysis, sepsis, and acute respiratory distress syndrome. This study investigates the critical issue of predicting 72-hour fatality in patients with severe hyperphosphatemia (≥ 10 mg/dL).

METHODS

We analyzed data from 530 patients treated at the Saitama Medical Center, Japan, from 2004 to 2019, including 153 72-hour fatalities. Multivariate logistic regression analysis (MLRA), Prediction One™ (Sony Network Communications Inc., Tokyo, Japan, https://predictionone.sony.biz/), and Light Gradient Boosting Machine (LightGBM) were used to predict fatalities. These methods were evaluated on a validation set of 331 patients from 2020 to 2023, including 104 fatalities. Calibration plots for training and validation data were used for comparison.

RESULTS

The fatality rate was 28.9% in the training data and 31.4% in the validation data. MLRA identified five fatality factors: age, low albumin, high aspartate aminotransferase, and elevated potassium and magnesium levels, with an area under the curve (AUC) of 0.848 (95% CI: 0.801, 0.890), sensitivity of 0.862, and specificity of 0.704. Prediction One™ achieved an AUC of 0.770 (95% CI: 0.722, 0.818), sensitivity of 0.654, and specificity of 0.769. LightGBM achieved an AUC of 0.948 (95% CI: 0.923, 0.973), sensitivity of 0.863, and specificity of 0.889. The validation calibration plot showed that MLRA had the closest regression coefficient to 1.0 at 0.903.

CONCLUSION

Although MLRA was the most accurate in predicting 72-hour fatalities, machine learning methods provided valuable insights into the importance of variables. Considering the high mortality rates associated with severe hyperphosphatemia, timely and accurate prognostication is essential in guiding immediate interventions and improving outcomes in emergency settings.

Change trends in serum phosphate levels predict in-hospital mortality in critically ill septic patients

Serum phosphate levels are strongly correlated with the prognosis of septic patients. However, previous studies have concentrated on individual phosphate levels, and the relationship between change trends in serum phosphate levels and in-hospital mortality has seldom been reported. We aimed to investigate whether the level and change trends of serum phosphate were associated with in-hospital mortality. We classified patients using k-means clustering analysis into clusters with changes in serum phosphate levels and used logistic regressions to explore the relationships between different clusters and in-hospital mortality, taking the cluster with the smallest change as a reference. Restricted cubic spline regression was used to examine the shape of the correlation between changes in serum phosphate levels and in-hospital mortality. Subgroup analyses and interaction analyses were performed to discover potential impact factors. A total of 1810 (21.1%) of 8586 participants died during their hospital stay. After adjustment for baseline variables, cluster 2 (OR 1.303, 95% CI 1.101-1.542, p = 0.002), cluster 3 (OR 1.348, 95% CI 1.158-1.57, p < 0.001), cluster 4 (OR 1.652, 95% CI 1.225-2.222, p = 0.001) and cluster 5 (OR 2.745, 95% CI 2.212-3.407, p < 0.001) remained associated with significantly increased mortality. The changes in serum phosphate levels and in-hospital mortality were linear according to restricted cubic spline regression. According to the subgroup analyses, the ORs of the female subgroup and mechanical ventilation subgroup were lower than those of their counterparts across all clusters. Multiplicative and additive interactions were detected between phosphate clusters and mechanical ventilation. First, a high and unstable serum phosphate level is associated with increased mortality in septic patients. Second, for those with elevated phosphate levels, treatments to lower serum phosphate may reduce mortality in septic patients. Third, an increasing trend in phosphate levels may be more important than a high level in predicting poor prognosis in septic patients.

Context-dependent change in the fitness effect of (in)organic phosphate antiporter glpT during Salmonella Typhimurium infection

Salmonella enterica is a frequent cause of foodborne diseases, which is attributed to its adaptability. Even within a single host, expressing a gene can be beneficial in certain infection stages but neutral or even detrimental in others as previously shown for flagellins. Mutants deficient for the conserved glycerol-3-phosphate and phosphate antiporter glpT have been shown to be positively selected in nature, clinical, and laboratory settings. This suggests that different selective pressures select for the presence or absence of GlpT in a context dependent fashion, a phenomenon known as antagonistic pleiotropy. Using mutant libraries and reporters, we investigated the fitness of glpT-deficient mutants during murine orogastric infection. While glpT-deficient mutants thrive during initial growth in the gut lumen, where GlpT's capacity to import phosphate is disadvantageous, they are counter-selected by macrophages. The dichotomy showcases the need to study the spatial and temporal heterogeneity of enteric pathogens' fitness across distinct lifestyles and niches. Insights into the differential adaptation during infection may reveal opportunities for therapeutic interventions.

Effect of changes trajectory of serum phosphate levels on the 28-day mortality risk in patients with sepsis: a retrospective cohort study from the MIMIC-IV database

BACKGROUND

Serum phosphate levels have been reported to be linked to the prognosis in critically ill patients. The purpose of this study was to analyze the impact of the trajectory of changes in serum phosphate levels on the short-term mortality risk in patients with sepsis.

METHODS

This retrospective cohort study used data on patients with sepsis from the 2008-2019 Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Serum phosphate level trajectories were constructed using a latent growth mixture modeling (LGMM) based on four measurements of serum phosphate at six-hour intervals within 24 h of admission to the intensive care unit (ICU). The relationship between serum phosphate levels at ICU admission and serum phosphate level trajectories and the risk of 28-day mortality in patients with sepsis was analyzed using Cox regression models, and hazard ratio (HR) and 95% confidence interval (CI) were calculated.

RESULTS

Of these 1,703 patients with sepsis included, 566 (33.24%) died within 28 days. The median serum phosphate levels of the patients were 4.10 (3.00, 5.50) mg/dL. Four serum phosphate level trajectories were classified: normal-level-steady trend (trajectory 1), high-level-steady trend (trajectory 2), high-level-decreasing trend (trajectory 3), and high-level-increasing trend (trajectory 4). High serum phosphate levels at admission were associated with a higher risk of 28-day mortality (HR = 1.05, 95%CI: 1.01-1.09) in patients with sepsis. For trajectories, trajectory 2 (HR = 1.27, 95%CI: 1.05-1.54) related to an increased risk of 28-day mortality compared with trajectory 1, whereas trajectory 4 (HR = 1.69, 95%CI: 0.99-2.91, P = 0.056) may be related. There was no significant difference in 28-day mortality between patients on trajectory 3 and trajectory 1 (P = 0.280). Subgroup analyses demonstrated that patients with trajectory 2 were linked to a higher risk of 28-day mortality in different population subgroups (P < 0.05).

CONCLUSION

Stable trajectories of high serum phosphate levels are an important risk factor for short-term mortality in patients with sepsis.

Effect of early serum phosphate disorder on in-hospital and 28-day mortality in sepsis patients: a retrospective study based on MIMIC-IV database

BACKGROUND

This study aims to assess the influence of early serum phosphate fluctuation on the short-term prognosis of sepsis patients.

METHODS

This retrospective study used the Medical Information Mart for Intensive Care IV database to analyze serum phosphate levels in sepsis patients within 3 days of ICU admission. According to the absolute value of delta serum phosphate (the maximum value minus the minimum value of serum phosphorus measured within three days), the patients were divided into four groups, 0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl. Meanwhile, the direction of delta serum phosphate was compared. With the serum phosphate change group of 0-1.3 mg/dl as the reference group, the relationship between delta serum phosphate and in-hospital mortality and 28-day mortality was analyzed by multivariate Logistics regression analysis.

RESULTS

The study involved 1375 sepsis patients. Serum phosphate changes (0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl) correlated with in-hospital and 28-day mortality variations (p = 0.005, p = 0.008). Much higher serum phosphate fluctuation elevated in-hospital and 28-day mortality. Compared to the 0-1.3 mg/dl change group, adjusted odds ratios (OR) in other groups for in-hospital mortality were 1.25 (0.86-1.81), 1.28 (0.88-1.86), and 1.63 (1.10-2.43), and for 28-day mortality were 1.21 (0.86-1.72), 1.10 (0.77-1.57), and 1.49 (1.03-2.19). Under the trend of increasing serum phosphate, the ORs of in-hospital mortality and 28-day mortality in ≥ 3.2 mg/dl group were 2.52 and 2.01, respectively.

CONCLUSION

In conclude, the delta serum phosphate ≥ 3.2 mg/dl was associated with in-hospital mortality and 28-day mortality in patients with sepsis.