Hyperphosphatemia is associated with high mortality in severe burns

Serum phosphate levels and the development of sepsis associated acute kidney injury: evidence from two independent databases

Objective

We aimed to investigate the association between serum phosphate levels and the risk for developing sepsis associated acute kidney injury (SAKI).

Methods

Septic patients from the Medical Information Mart for Intensive Care IV (MIMIC IV) and the eICU Collaborative Research Database (eICU-CRD) were enrolled. Restricted cubic spline (RCS) was used to visualize the relationship between phosphate levels and the risk of SAKI. Patients were divided into four categories based on their serum phosphate levels. Logistic regression analysis, receiver operating characteristic (ROC) curve and subgroup analysis were performed to evaluate the predictive value of serum phosphate for SAKI.

Results

A total of 9,244 and 2,124 patients from the MIMIC IV and eICU-CRD database were included in the final analysis. RCS curve revealed a non-linear correlation between phosphate levels and the risk of SAKI (p for non-linearity <0.05). Each 1 mg/dL increase in phosphate levels was associated with a 1.51 to 1.64-fold increased risk of SAKI (OR 2.51-2.64, p < 0.001) in the MIMIC IV cohort and a 0.29 to 0.38-fold increased risk (OR 1.29-1.38, p < 0.001) in the eICU-CRD cohort. Compared to the normal-low category, hyperphosphatemia and normal-high category were independently associated with an increased risk of SAKI, while hypophosphatemia was independently associated with a decreased risk in the MIMIC IV cohort. A similar trend was observed in the eICU-CRD cohort, but statistical significance disappeared in the hypophosphatemia category and the adjusted model of normal high category. These finding was consistent in subgroup analysis.

Conclusion

Elevated serum phosphate, even within the normal range, is an independent risk factor for developing SAKI in septic patients. Abnormal change in serum phosphate levels may be a novel biomarker for early prediction of SAKI occurrence.

Initial Laboratory Values Can Predict Mortality in Burn Patients

BACKGROUND

There are several burn scores used to predict mortality in burn patients. However, minimal data exists on the role of laboratory values in risk stratification. We hypothesized that laboratory derangements seen on admission can predict mortality in burn patients.

MATERIALS AND METHODS

A retrospective chart review was conducted on burn patients admitted to a busy Level 1 Trauma and Burn Center from 2013 to 2019. Data analysis included patients with partial or full thickness burns and a total body surface area (TBSA) burn greater than 15%. Exclusion criteria included patients presenting with electrical burns, non-thermal conditions (Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis, or soft tissue infections) or patients with significant polytrauma.

RESULTS

112 patients were included in the analysis. Admission phosphate, creatinine, albumin, and glucose levels were associated with mortality. There was a difference in serum phosphate (3.48 and 6.04 mg/dL), creatinine (0.85 and 1.13 mg/dL), albumin (3.26 and 2.3 mg/dL), and glucose (138 and 233 mmol/L) levels for survivors and non-survivors; respectively. There were increased mortality rates seen in patients presenting with abnormal serum levels compared to normal serum levels (Phosphate: 7.5% vs. 53.3%, creatinine: 13.5% vs. 38.9%, albumin: 38.5% vs. 8.10% and glucose: 10.1% vs. 31.6% (normal vs. abnormal; respectively)). Serum sodium, potassium, and hemoglobin levels had no association with mortality.

DISCUSSION

Specific laboratory derangements seen on admission are associated with an increased risk for mortality. This can be used as a framework for future studies in risk stratification of burn victims.

ANALYSIS OF THE RELATIONSHIP BETWEEN EARLY SERUM PHOSPHATE LEVELS AND SHORT-TERM MORTALITY IN SEPTIC PATIENTS: A RETROSPECTIVE STUDY BASED ON MIMIC-IV

ABSTRACT

Objective: The aim of the study is to explore the impact of early serum phosphate levels on the prognosis of critically ill patients with sepsis. Methods: In this retrospective large cohort study, data of patients with sepsis were obtained from the Medical Information Mart for Intensive Care IV database. Patients were retrospectively divided into a control group and three study groups according to their daily serum phosphate levels within 2 days of intensive care unit (ICU) admission. A Cox regression model was used to evaluate the association between serum phosphate levels and 28-day morbidity. Results: This study included 9,691 patients diagnosed with sepsis. During the first 2 days of ICU admission, patients with hyperphosphatemia in either of the 2 days had higher 28-day mortality, while patients in the hypophosphatemia group had lower 28-day mortality (first day, 32.9% vs. 16.3%; second day, 36.3% vs. 14.7%). After adjusting for potential confounders, hyperphosphatemia was significantly associated with 28-day mortality; however, only hypophosphatemia on the second day was independently associated with reduced 28-day mortality. After stratification in the hypophosphatemia group, subgroup analysis showed that only the association between the mild hypophosphatemia group and 28-day mortality reached statistical significance (hazard ratio = 0.76, 95% CI = 0.65-0.89, P = 0.001). Conclusions: Mild hypophosphatemia might improve the short-term prognosis of patients with sepsis, and hyperphosphatemia is an independent risk factor for the outcomes of septic patients. After ICU admission, the serum phosphate levels on the second day had a better independent correlation with 28-day mortality, which prompted us to reconsider the optimal timing of phosphate evaluation.

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

Hypo- and Hyperphosphatemia at Admission as Independent Factors of Mortality of COVID-19 Patients: Findings from a Retrospective Cohort Study

BACKGROUND

Electrolyte imbalances are common in COVID-19 infection and are associated with poor outcomes in hospitalized patients.

OBJECTIVES

This study examined whether serum phosphate imbalances at admission are associated with mortality in hospitalized COVID-19 patients.

METHODS

In this registry-based single-center retrospective cohort study, 1349 inpatients with COVID-19 were included from March 2020 to March 2021 in an academic hospital in Ilam (southwest Iran). The Cox proportional hazard (PH) regression model was applied to the data set of COVID-19.

RESULTS

The in-hospital median survival time for patients with low, normal, and high serum phosphate levels was 14, 25, and 8 days, respectively. In a multivariate model, adjusted for the other variables, patients with hypophosphatemia (adjusted hazard ratio [HR], 2.53; 95% CI, 1.15 - 5.58; P = 0.02) and hyperphosphatemia (adjusted HR, 1.77; 95% CI, 1.00 - 3.14; P = 0.05) had an increased mortality hazard compared with those who had normal levels of serum phosphate.

CONCLUSIONS

Our results demonstrate associations of hypophosphatemia and hyperphosphatemia with increased in-hospital mortality in COVID-19 patients. Intensive medical care and more attention must be paid to COVID-19 patients with serum phosphate imbalances at admission.

Hyperphosphatemia and Outcomes in Critically Ill Patients: A Systematic Review and Meta-Analysis

Introduction

Serum phosphate level is often deranged during critical illness. Hyperphosphatemia, as a marker of disease severity, attracts more and more attention. This study aimed to evaluate the impact of hyperphosphatemia on clinical outcomes in critically ill patients.

Methods

We searched for relevant studies in PubMed, EMBASE, and the Cochrane database up to Jan 10, 2022. Two authors independently screened studies, extracted data, and assessed the study quality. Meta-analyses were performed to determine hyperphosphatemia prevalence and evaluate its relationship with prognosis and important clinical outcomes. We also conducted subgroup analysis and sensitivity analyses to explore the sources of heterogeneity.

Results

Ten studies with 60,358 patients met the inclusion criteria. These studies were moderate to high quality. The median prevalence of hyperphosphatemia was 30% (range from 5.6 to 45%). Patients with hyperphosphatemia had a significantly higher risk of all-cause mortality than those without (OR 2.85; 95% CI, 2.35 to 3.38, P < 0.0001). Subgroup analyses, sensitivity analyses, and regression analyses further confirmed these results. In addition, patients with hyperphosphatemia required more CRRT (OR 4.96; 95% CI, 2.43 to 10.2, P < 0.0001) but not significantly increased duration of mechanical ventilation (mean difference, MD 0.13, 95% CI −0.04 to 0.30; P = 0.138), length of stay in intensive care unit (ICU) (SMD 0.164 day, 95% CI −0.007 to 0.335; P = 0.06), and length of stay in hospital (SMD 0.005 day, 95% CI −0.74 to 0.75; P = 0.99).

Conclusions

Our results indicated that hyperphosphatemia was associated with all-cause mortality in critically ill patients. However, due to the retrospective design of the included studies, more prospective, well-designed research is required in the future.

Systematic Review Registration

[https://doi.org/10.37766/inplasy2021.12.0130], identifier [INPLASY2021120130].

Effect of Serum Phosphate on the Prognosis of Septic Patients: A Retrospective Study Based on MIMIC-IV Database

Objective

To assess the effect of serum inorganic phosphate (Pi) on the prognosis of patients with sepsis.

Methods

A retrospective analysis of patients with sepsis selected from the Medical Information Mart for Intensive Care (MIMIC)-IV database was performed. Sepsis was diagnosed according to the Third International Consensus Definition for sepsis and septic shock (Sepsis-3). The time-weighted values of the serum Pi measurements within the first 24 h of sepsis were analyzed. The association between serum Pi and in-hospital mortality was evaluated with a generalized linear model (log-binomial model).

Results

The analysis of 11,658 patients from six intensive care units (ICUs) showed a nearly linear correlation between serum Pi and in-hospital mortality in all patients with sepsis, especially in those with acute kidney injury (AKI). The increase of serum Pi was related to a higher risk of AKI, higher norepinephrine doses, ICU mortality, and in-hospital mortality. The generalized linear model showed that serum Pi was an independent predictor for in-hospital mortality in all patients with sepsis even within the normal range. The adjusted risk ratios (RRs) were also significant in subgroup analyses according to kidney function, gender, respiratory infection, vasopressor use, and Sequential Organ Failure Assessment (SOFA) score.

Conclusion

Higher levels of serum Pi, even within the normal range, were significantly associated with a higher risk of in-hospital mortality in patients with sepsis regardless of kidney function, gender, respiratory infection, vasopressor use, and SOFA score.

Association between early elevated phosphate and mortality among critically ill elderly patients: a retrospective cohort study

Background

Phosphate disturbances are relatively common in hospitalized patients, especially in critically ill patients. The abnormal phosphate levels may indicate an abnormal body condition. However, little is known about the association between elevated serum phosphate and outcome in critically ill elderly patients. Therefore, the purpose of the present study was to investigate the association between early elevated phosphate and mortality in critically ill elderly patients.

Methods

The present study was a retrospective cohort study based on the medical information mart for intensive care IV (MIMIC-IV) database. Patients with age ≥60 years old were enrolled in the present study. The primary outcome in the present study was ICU mortality. Univariate and multivariate Cox proportional hazard regression analyses were used to evaluate the association between early elevated phosphate and ICU mortality in critically ill elderly patients.

Results

Twenty-four thousand two hundred eighty-nine patients were involved in this analysis and 2,417 patients died in ICU. The median age of involved patients was 78.4 (67.5, 82.9) years old. The median level of serum phosphate in the survivor group was 3.6 (3.0, 4.3) mg/dL, and the median level of serum phosphate in the non-survivor group was 4.4 (3.4, 5.8) mg/dL. The level of serum phosphate in the non-survivor group was significantly higher than the survivor group (4.4 vs. 3.6, P<0.001). The multivariate Cox proportional hazard regression demonstrated that elevated phosphate was an independent risk factor for ICU mortality, after adjustment for other covariates (HR=1.056, 95%CI: 1.028-1.085, P<0.001).

Conclusions

In critically ill elderly patients, early elevated phosphate was significantly associated with increased ICU mortality.

Association of Serum Phosphate Derangement With Mortality in Patients on Continuous Renal Replacement Therapy

Background:

There is limited evidence on the association of serum phosphate with mortality in patients receiving continuous renal replacement therapy (CRRT).

Objective:

To assess the association of serum phosphate with mortality in critically ill patients requiring CRRT for acute kidney injury (AKI).

Design:

A cohort study.

Setting:

A tertiary referral hospital in the United States.

Patients:

Acute kidney injury patients receiving CRRT from 2006 through 2015 in intensive care units.

Measurements:

(1) Serum phosphate before CRRT and (2) mean serum phosphate during CRRT were categorized into 3 groups; ≤2.4 (hypophosphatemia), 2.5 to 4.5 (normal serum phosphate group), and ≥4.6 (hyperphosphatemia) mg/dL.

Methods:

Multivariable logistic regression was used to assess the association between serum phosphate and 90-day mortality.

Results:

A total of 1108 patients were included in this study. Of these, 55% died within 90 days after CRRT initiation. Before CRRT, 3%, 30%, and 66% had hypophosphatemia, normophosphatemia, and hyperphosphatemia, respectively. Before CRRT, both hypophosphatemia and hyperphosphatemia were significantly associated with higher 90-day mortality with the adjusted odds ratio (OR) of 2.22 (95% confidence interval [CI]: [1.03, 4.78]) and 1.62 (95% CI: [1.21, 2.18]), respectively. During CRRT, 3%, 85%, and 12% had mean serum phosphate in hypophosphatemia, normophosphatemia, and hyperphosphatemia range. During CRRT, hyperphosphatemia was significantly associated with higher 90-day mortality with adjusted OR of 2.22 (95% CI: [1.45, 3.38]).

Limitations:

Single center, observational design, lack of information regarding causes of serum phosphate derangement.

Conclusion:

Most CRRT patients had hyperphosphatemia before CRRT initiation but maintain normal serum phosphate during CRRT. Before CRRT, hypo- and hyperphosphatemia, and during CRRT, hyperphosphatemia predicted higher mortality.

Trial registration:

Not registered.

Association between serum phosphate and mortality in critically ill patients: a large retrospective cohort study

OBJECTIVES

This research aims to explore the impact of serum phosphate on the mortality of critically ill patients.

DESIGN

A retrospective large cohort study.

SETTING

Our data were extracted from a publicly accessible database named 'Multiparameter Intelligent Monitoring in Intensive Care Database III'.

PARTICIPANTS

27 131 patients were included by clear definitions of selection and exclusion criteria.

INTERVENTIONS

We used initial phosphate at admission as a design variable. Patients were divided into six groups with different serum phosphate levels and five groups at different intensive care unit (ICU) departments.

PRIMARY AND SECONDARY OUTCOMES

28-day and 90-day mortality were primary outcomes. All-cause mortality and length of stay ICU were secondary outcomes.

RESULTS

Patients with very-high-normal serum phosphate, hypophosphataemia and hyperphosphataemia had worse outcomes. And the relationship between serum phosphate and the probability of 28-day or 90-day mortality had a linear relationship. After adjustment for potential confounders, hypophosphataemia and hyperphosphataemia were not significantly associated with 28-day or 90-day mortality. Nevertheless, at the medical ICU, hyperphosphataemia was associated with increased 28-day or 90-day mortality (HR=0.64, 95% CI 0.48 to 0.84, p=0.0017; HR=0.72, 95% CI 0.57 to 0.91, p=0.0067, respectively), using group 2 (≥2.5 mg/dL and <3.0 mg/dL) as the reference group.

CONCLUSIONS

Patients with very-high-normal serum phosphate also had worse outcomes, it might be necessary to re-evaluate the definitions of the normal reference range for serum phosphate. Hypophosphataemia and hyperphosphataemia are not the independent risk factors of 28-day or 90-day ICU mortality, which leads us to consider whether phosphate monitoring is not a necessary measure in critically ill patients. But hyperphosphataemia was associated with increased 28-day or 90-day mortality at the medical ICU, which emphasises the potential importance of early diagnosis and treatment of hyperphosphataemia for the patients who were admitted to the medical ICU.

Association between the initial serum phosphate level and 30-day mortality in blunt trauma patients

BACKGROUND

Studies on patients with cardiac arrest or sepsis have reported that high initial phosphate levels are associated with poor outcomes. However, no previous study has investigated the association between initial phosphate levels and outcomes in blunt trauma patients.

METHODS

This study was a retrospective observational study conducted on blunt trauma patients who had been treated at the single regional trauma center between January 2016 and December 2017. Patients' demographic data, initial vital signs, trauma scores, and laboratory parameters including phosphate levels were collected from the trauma registry. The primary outcome was set to 30-day mortality. The secondary outcomes were the total volume of blood transfused, 30-day hospital-free days, and 30-day intensive care unit-free days.

RESULTS

Of the 1,907 included patients, 1,836 were in the survival group, and 71 were in the nonsurvival group. The nonsurvival group had a significantly higher phosphate level than the survival group. Patients in the hyperphosphatemia group had a higher 30-day mortality, fewer 30-day intensive care unit-free days, and higher transfusion volume than those in the other groups. In multivariable logistic regression analysis, hyperphosphatemia was independently associated with 30-day mortality. The receiver operating characteristic curve analysis showed that the area under the curve with the inclusion of phosphate in addition to Injury Severity Score, Revised Trauma Score, and age was 0.911. Area under the curve was also increased when phosphate was simply added to Injury Severity Score and Revised Trauma Score.

CONCLUSION

In blunt trauma patients, hyperphosphatemia was associated with an increased 30-day mortality.

LEVEL OF EVIDENCE

Prognostic, level III.

Meta-Analysis of Renal Replacement Therapy for Burn Patients: Incidence Rate, Mortality, and Renal Outcome

Background: Renal replacement therapy (RRT) was often needed by some severe burn patients with acute kidney injury (AKI). The primary aim of this study was to review incidence rate and mortality of RRT in severe burn patients. Second aims were to review RRT complications and renal outcome.

Methods: We searched multiple databases for studies published between 1 January 1960 and 31 December 2019. Studies about adult populations with burn injury, providing epidemiologic data on prevalence or mortality of RRT, were included.

Results: A total of selected 57 studies, including 27,437 patients were enrolled in our analysis. The prevalence rates of RRT were 8.34% (95% CI 7.18–9.5%) in all burn patients and 37.05% (95% CI 29.85–44.24%) in AKI patients. The mortality of all burn patients with RRT was 65.52% (95% CI 58.41–72.64%). The prevalence rates of RRT in sample size≥100 group were 6.86% (95% CI 5.70–8.03%), which was lower than that of <100 group (17.61%, 95% CI 13.39–21.82%). With the increase of TBSA, the prevalence of RRT may have the increasing trend. The prevalence rates of RRT in Asian group was 12.75% (95% CI 9.50–16.00%), which was higher than that of European (10.45%, 95% CI 7.30–13.61%) and North America group (5.61%, 95% CI 4.27–6.95%). The prevalence rates of RRT in 2010–2019 group was 12.22% (95% CI 10.09–14.35%), which was higher than that of 2009–2000 group (5.17%, 95% CI 2.88–7.46%). The prevalence rates of RRT in 1989 and before group was the lowest, which was 1.56% (95% CI 0–3.68%). However, there was no significant correlation between the year of publication and the mortality of burn patients with RRT. Dialysis-requiring AKI in burn patients could increases the risk of chronic kidney disease progression and end-stage renal disease. About 35% of RRT patients need to maintain haemodialysis temporarily, even if they survive and leave hospital.

Conclusions: The prevalence rate of RRT is about 6–8%; approximately, one-third of burn patients with AKI need RRT. The prevalence rate of RRT increased over time, but the mortality did not change. The prevalence rates of RRT in Asian group was higher than that of European and North America group.

ICU-Admission Hyperphosphataemia Is Related to Shock and Tissue Damage, Indicating Injury Severity and Mortality in Polytrauma Patients

Hyperphosphataemia can originate from tissue ischaemia and damage and may be associated with injury severity in polytrauma patients. In this retrospective, single-centre study, 166 polytrauma patients (injury severity score (ISS) ≥ 16) primarily requiring intensive care unit (ICU) treatment were analysed within a five-year timeframe. ICU-admission phosphate levels defined a hyperphosphataemic (>1.45 mmol/L; n = 56) opposed to a non-hyperphosphataemic group (n = 110). In the hyperphosphataemic group, injury severity was increased (ISS median and IQR: 38 (30–44) vs. 26 (22–34); p < 0.001), as were signs of shock (lactate, resuscitation requirements), tissue damage (ASAT, ALAT, creatinine) and lastly in-hospital mortality (35.7% vs. 5.5%; p < 0.001). Hyperphosphataemia at ICU admission was shown to be a risk factor for mortality (1.46–2.10 mmol/L: odds ratio (OR) 3.96 (95% confidence interval (CI) 1.03–15.16); p = 0.045; >2.10 mmol/L: OR 12.81 (CI 3.45–47.48); p < 0.001) and admission phosphate levels alone performed as good as injury severity score (ISS) in predicting in-hospital mortality (area under the ROC curve: 0.811 vs. 0.770; p = 0.389). Hyperphosphataemia at ICU admission is related to tissue damage and shock and indicates injury severity and subsequent mortality in polytrauma patients. Admission phosphate levels represent an easily feasible yet strong predictor for in-hospital mortality.

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis

BACKGROUND

Sepsis is the leading cause of hospitalization and death in the intensive care unit. It is vital to identify high-risk patients with poor prognosis in the early stages of sepsis. We aimed to investigate the prognostic value of serum phosphorus levels for sepsis.

METHODS

The data of 4767 patients with sepsis were collected from the Multiparameter Intelligent Monitoring in Intensive Care III database. The Locally Weighted Scatterplot Smoothing technique and Kaplan-Meier analysis were used to test the crude relationship between serum phosphorus levels and mortality or overall survival. The multivariable logistic regression was used to further analyze the relationship between serum phosphorus levels and in-hospital mortality. The subgroup analysis was performed according to renal failure, use of vasopressin and the Sequential Organ Failure Assessment (SOFA) score.

RESULTS

Only hyperphosphatemia significantly correlated with in-hospital mortality [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.19-1.85], while the correlation between hypophosphatemia and in-hospital mortality was not significant (OR 0.91; 95% CI 0.70-1.19). The interactions between serum phosphorus and renal failure, use of vasopressin or the SOFA score were not significant.

CONCLUSIONS

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis.

Impact of Admission Calcium-phosphate Product on 1-year Mortality among Hospitalized Patients

Background

Calcium-phosphate product is associated with mortality among patients with end-stage kidney disease on dialysis. However, clinical evidence among hospitalized patients is limited. The objective of this study was to investigate the relationship between admission calcium-phosphate product and 1-year mortality in hospitalized patients.

Materials and Methods

All adult patients admitted to a tertiary referral hospital in 2009-2013 were studied. Patients who had both available serum calcium and phosphate measurement within 24 h of hospital admission were included. Admission calcium-phosphate product (calcium × phosphate) was stratified based on its distribution into six groups: <21, 21-<27, 27-<33, 33-<39, 39-<45, and ≥45 mg²/dL². Multivariate cox proportional hazard analysis was performed to evaluate the association between admission calcium-phosphate product and 1-year mortality, using the calcium-phosphate product of 33-<39 mg²/dL² as the reference group.

Results

A total of 14,772 patients were included in this study. The mean admission calcium-phosphate product was 34.4 ± 11.3 mg²/dL². Of these patients, 3194 (22%) died within 1 year of hospital admission. In adjusted analysis, admission calcium-phosphate product of ≥45 mg²/dL² was significantly associated with increased 1-year mortality with hazard ratio of 1.41 (95% 95% confidence interval 1.25-1.67), whereas lower admission calcium-phosphate product was not significantly associated with 1-year mortality.

Conclusion

Elevated calcium-phosphate product was significantly associated with increased 1-year mortality in hospitalized patients.

Prevalence and prognostic impact of inhalation injury among burn patients: A systematic review and meta-analysis

BACKGROUND

The objective of our study was to perform a systematic review and meta-analysis aimed at assessing the prevalence of inhalation injury in burn patients and its prognostic value in relation to in-hospital mortality.

METHODS

We searched the PubMed and EMBASE databases for noninterventional studies published between 1990 and 2018 investigating in-hospital mortality predictors among burn patients.The primary meta-analysis evaluated the association between inhalation injury and mortality. A secondary meta-analysis determined the global estimate of the prevalence of inhalation injury and the rate of mortality. Random effects models were used, and univariate meta-regressions were used to assess sources of heterogeneity. This study is registered in the PROSPERO database with code CRD42019127356.

FINDINGS

Fifty-four studies including a total of 408,157 patients were selected for the analysis. A pooled inhalation prevalence of 15.7% (95% confidence interval, 13.4%-18.3%) was calculated.The summarized odds ratio of in-hospital mortality secondary to an inhalation injury was 3.2 (95% confidence interval, 2.5-4.3). A significantly higher odd of mortality was found among the studies that included all hospitalized burn patients, those that included a lower proportion of male patients, those with a lower mean total body surface area, and those with a lower prevalence of inhalation injury.

CONCLUSION

Despite our study's limitations due to the high risk of bias and the interstudy heterogeneity of some of our analyses, our results revealed a wide range of prevalence rates of inhalation injury and a significant association between this entity and in-hospital mortality in burn patients. However, this association is not significant if adjusted for disease severity.

LEVEL OF EVIDENCE

Systematic review/meta-analysis, level III.

Changes in serum phosphorus level in patients with severe burns: A prospective study

BACKGROUND

The second most abundant mineral in the body, phosphorus (P), is absorbed in the small intestine after ingestion enhanced by 1,25-dihydroxy vitamin D, and its excretion is exclusively regulated by the kidney. It is clinically significant, aside from its disturbance in burn ICU patient's P mechanism. The increasing rate of morbidity and mortality among the patients can be associated with severe hypophosphatemia. The current study aimed at investigating the changes in serum P levels in the early period after burns, the relationship between serum P level and TBSA (total body surface area) of burn, and the impact of hypophosphatemia on patients' clinical outcomes.

MATERIAL AND METHODS

The current prospective, observational study was conducted on 137 patients hospitalized in the burn intensive unit (BICU) of Velayat Sub-specialty Burn and Plastic Surgery Center from December 2015 to May 2017. According to the TBSA percentage, the patients were divided into three groups. The level of serum P was determined in the 1st, 3rd, 5th, 7th, and 9th days of hospital stay and before discharge. To evaluate the trend of P changes in the sixtime-points, the average changes along with 95% confidence intervals (CI) were used for multivariate analysis of variance with repeated measures (repeated measures ANOVA). A P-value of 0.05 or less was considered statistically significant. The analyses were performed using SPSS software, version 19 (SPSS Inc.).

RESULTS

Totally, 137 patients (70% male, mean age 32 ± 21years, and TBSA 32.6 ± 14%) were included in the study. The overall incidence of hypophosphatemia was 75.1%. Hypophosphatemia developed as early as 1.66 ± 0.136 (95%CI: 1.4-1.9) days after injury. The highest decrease in the serum P level was observed on the 3rd and 5th days after burn as 2.78 mg/dL and 2.85 mg/dL, respectively (P-value = 0.001). A correlation was observed between TBSA and serum P level. The mean serum P level decreased with increasing the percentage of burns. There was a correlation between serum P level and mortality; therefore, a decrease in serum P level increased the patient's mortality rate (P < 0.05).

CONCLUSION

The current study highlighted that hypophosphatemia is often observed in patients with burn injuries during their hospitalization. It is potentially beneficial to identify patients at risk of hypophosphatemia. Therefore, it is suggested that P level be assessed regularly in patients with burn injuries for the timely initiation of P replacement therapy.