Cohort study of serum total cholesterol and in-hospital incidence of infectious diseases

Dyslipidemia in the Critically Ill

Total and HDL cholesterol levels fall at the onset of acute illness and the cholesterol levels normalize as the patient recovers. Hypocholesterolemia may predispose the critically ill patient to sepsis and adrenal failure. Early enteral nutrition and tight glycemic control accelerate the recovery of the cholesterol levels.

The Relationships of Hypocholesterolemia to Cytokine Concentrations and Mortality in Critically Ill Patients with Systemic Inflammatory Response Syndrome

BACKGROUND

Decreased concentrations of total cholesterol, lipoproteins, and lipoprotein cholesterols occur early in the course of critical illness. Low cholesterol concentrations correlate with high concentrations of cytokines such as interleukin (IL)-6 and IL-10, and may be due to decreased synthesis or increased catabolism of cholesterol. Low cholesterol concentrations have been associated clinically with several adverse outcomes, including the development of nosocomial infections. The study was performed to test the hypothesis that a low cholesterol concentration predicts mortality and secondarily predicts the development of organ dysfunction in critical surgical illness.

METHODS

A prospective study was undertaken of 215 patients admitted to a university surgical ICU with systemic inflammatory response syndrome (SIRS). Serial blood samples were collected within 24 h of admission, as well as on the morning of days 2, 4, and 7 of the ICU stay for as long as the patients were in the ICU. Demographic data and predetermined outcomes were noted.

RESULTS

One hundred nine patients had at least two samples drawn and form the population for analysis. Sixty-two of the patients had three samples obtained, whereas 42 patients had four samples obtained. By univariate analysis, non-survivors were more severely ill on admission (APACHE III), more likely to have been admitted to the ICU as an emergency, more likely to develop a nosocomial infection, and more likely to develop severe organ dysfunction (MODS) (all, p < 0.05). Death was associated on day 1 with increased concentrations of sIL2R, IL-6, IL-10, and sTNFR-p75 (all, p < 0.01), but there were initially no differences in serum lipid concentrations. However, by day 2, concentrations of IL-6, IL-10, and cholesterol had decreased significantly (all, p < 0.05) from day 1 in non-survivors but not in survivors; the difference in serum cholesterol concentration persisted to day 7 (p < 0.05). Persistently elevated concentrations of IL-6 and IL-10 were observed in patients who developed severe MODS. By logistic regression, increased APACHE III score, development of a nosocomial infection, and decreased cholesterol concentration were independently associated with mortality.

CONCLUSIONS

Decreased serum cholesterol concentration is an independent predictor of mortality in critically ill surgical patients. Repletion of serum lipids is a feasible therapeutic approach for the management of critical illness.

Following severe injury, hypocholesterolemia improves with convalescence but persists with organ failure or onset of infection

Introduction

Our primary objective was to determine the impact of traumatic injury, onset of infection, organ/metabolic dysfunction, and mortality on serum cholesterol.

Methods

During 676 surgical intensive care unit (SICU) days, 28 ventilated trauma patients underwent daily measurement of white blood cell (WBC) count and differential, cholesterol, arterial oxygen tension/fractional inspired oxygen, bilirubin, glucose, creatinine, and bicarbonate. With the onset of infection, WBC response was considered positive if the WBC count was 16.0 or greater, immature neutrophils were 10% or greater, or WBC count increased by 20%. Cholesterol response was considered positive if cholesterol decreased or failed to increase by 10%.

Results

Injury Severity Score was 30.6 ± 8.6 and there were 48 infections. Initial cholesterol was decreased (119 ± 44 mg/dl) compared with expected values from a database (201 ± 17 mg/dl; P < 0.0001). The 25 survivors had higher cholesterol at SICU discharge (143 ± 35 mg/dl) relative to admission (112 ± 37 mg/dl; P < 0.0001). In the three patients who died, the admission cholesterol was 175 ± 62 mg/dl and the cholesterol at death was 117 ± 27 mg/dl. The change in percentage of expected cholesterol (observed value divided by expected value) from admission to discharge was different for patients surviving (16 ± 19%) and dying (-29 ± 19%; P = 0.0005). With onset of infection, the WBC response was positive in 61% and cholesterol response was positive in 91% (P = 0.001). Percentage of expected cholesterol was decreased with each system dysfunction: arterial oxygen tension/fractional inspired oxygen < 350, creatinine > 2.0 mg/dl, glucose > 120 mg/dl, bilirubin > 2.5 mg/dl, and bicarbonate ≥ 28 or ≤ 23 (P < 0.01). Percentage of expected cholesterol decreased as the number of dysfunctions increased (P = 0.0001).

Conclusion

Hypocholesterolemia is seen following severe injury. Convalescing patients (ready for SICU discharge) have improved cholesterol levels, whereas dying patients appear to have progressive hypocholesterolemia. Decreasing or fixed cholesterol levels suggest the development of infection or organ/metabolic dysfunction. Cholesterol responses are more sensitive for the onset of infection than are WBC responses. Sequential cholesterol monitoring is recommended for patients with severe trauma.

Serum cholesterol levels and in-hospital mortality in the elderly

PURPOSE

Although total cholesterol levels among middle-aged persons correlate with long-term mortality from all causes, this association remains controversial in older persons. We explored whether total cholesterol levels were independently associated with in-hospital mortality among elderly patients.

METHODS

We analyzed data from a large collaborative observational study, the Italian Group of Pharmacoepidemiology in the Elderly (GIFA), which collected data on hospitalized patients. A total of 6984 patients aged 65 years or older who had been admitted to 81 participating medical centers during four survey periods (from 1993 to 1998) were enrolled. Patients were divided into four groups based on total cholesterol levels at hospital admission: <160 mg/dL (n = 2115), 160 to 199 mg/dL (n = 2210), 200 to 239 mg/dL (n = 1719), and >or=240 mg/dL (n = 940).

RESULTS

Patients (mean [+/- SD] age, 78 +/- 7 years) were hospitalized for an average of 15 +/- 10 days. The mean total cholesterol level was 186 +/- 49 mg/dL. A total of 202 patients died during hospitalization. Mortality was inversely related to cholesterol levels (<160 mg/dL: 5.2% [110/2115]; 160-199 mg/dL: 2.2% [49/2210]; 200-239 mg/dL: 1.6% [27/1719]; and >or=240 mg/dL: 1.7% [16/940]; P for linear trend <0.001). After adjustment for potential confounders (demographic characteristics, smoking, alcohol use, indicators of nutritional status, markers of frailty, and comorbid conditions), low cholesterol levels continued to be associated with in-hospital mortality. Compared with patients who had cholesterol levels <160 mg/dL, the odds ratios for in-hospital mortality were 0.49 (95% confidence interval [CI]: 0.34 to 0.70) for participants with cholesterol levels of 160 to 199 mg/dL, 0.41 (95% CI: 0.26 to 0.65) for those with cholesterol levels of 200 to 239 mg/dL, and 0.56 (95% CI: 0.32 to 0.98) for those with cholesterol levels >or=240 mg/dL. These estimates were similar after further adjustment for inflammatory markers and after excluding patients with liver disease.

CONCLUSIONS

Among older hospitalized adults, low serum cholesterol levels appear to be an independent predictor of short-term mortality.

Safety and pharmacokinetics of an endotoxin-binding phospholipid emulsion

BACKGROUND

Lipids and lipoproteins have been shown to bind and neutralize endotoxin and to improve outcomes in animal models of sepsis.

OBJECTIVE

To provide safety and pharmacokinetic data for a protein-free, phospholipid-rich emulsion developed as an agent to neutralize endotoxin, and to study the changes in lipids and lipoproteins following emulsion administration.

METHODS

Thirty healthy male volunteers (aged 18-45 y) were given an emulsion containing 92.5% soy phospholipid, 7.5% soy triglyceride, and 18 mM sodium cholate using a double-blind, placebo-controlled crossover protocol. Emulsion at 3 escalating doses (75, 150, 300 mg/kg) based on phospholipid content was administered by intravenous infusion over 2 hours in the low- and mid-dose groups and 6 hours in the high-dose group.

RESULTS

All subjects completed the protocol without significant toxicities. A slight dose-dependent increase in indirect bilirubin at the 24-hour time point was observed in the emulsion treatment period, with a maximum difference between placebo and emulsion of 0.9 mg/dL. Mean +/- SD peak phospholipid levels were 316 +/- 30, 533 +/- 53, and 709 +/- 86 mg/dL, and phospholipid half-lives were 5.4 +/- 0.6, 5.4 +/- 0.5, and 8.0 +/- 0.8 hours for the low, mid, and high doses, respectively. Increases in total cholesterol, low-density lipoprotein cholesterol and apolipoprotein A-I and B levels were observed. High-density lipoprotein cholesterol decreased immediately following emulsion infusion, but rebounded to above placebo levels by 24 hours.

CONCLUSIONS

A unique phospholipid-rich emulsion was shown to have a favorable safety profile and to expand the blood lipid and lipoprotein pool without the use of human-derived blood products. Lipid levels expected to protect against the physiologic effects of bacterial endotoxin were achieved.

Protein-free phospholipid emulsion treatment improved cardiopulmonary function and survival in porcine sepsis

Lipoprotein phospholipid (PL) plays a major role in neutralization of endotoxin. This study tested the hypothesis that prophylactic administration of a PL-enriched emulsion (PRE), which augments PL content of serum lipoproteins and neutralizes endotoxin in vitro, would preserve cardiovascular function and improve survival in porcine septic peritonitis. A control group was compared with low-, mid-, and high-dose treatment groups that received PRE by primed continuous infusion for 48 h. A fibrin clot containing live Escherichia coli 0111.B4 was implanted intraperitoneally 30 min after the priming dose. Survival increased in a dose-dependent manner and was correlated with serum PL. Infused PL was associated with high-density lipoprotein in the low-dose group and all serum lipoproteins at higher doses. Treatment significantly lowered serum endotoxin and tumor necrosis factor (TNF)-alpha, preserved cardiac output and ejection fraction, and attenuated increases in systemic and pulmonary vascular resistances. This study demonstrated that augmentation of lipoprotein PL via administration of PRE improved survival and offered a novel therapeutic approach to sepsis.

Relationship of hypolipidemia to cytokine concentrations and outcomes in critically ill surgical patients

OBJECTIVE

To determine the relationship of hypolipidemia to cytokine concentrations and clinical outcomes in critically ill surgical patients.

DESIGN

Consecutive, prospective case series.

SETTING

Surgical intensive care unit of an urban university hospital.

PATIENTS

Subjects were 111 patients with a variety of critical illnesses, for whom serum lipid, lipoprotein, and cytokine concentrations were determined within 24 hrs of admission to a surgical intensive care unit. Controls were 32 healthy men and women for whom serum lipid, lipoprotein, and cytokine concentrations were determined.

INTERVENTIONS

Blood samples were drawn on admission to the intensive care unit. Predetermined clinical outcomes including death, infection subsequent to intensive care unit admission, length of intensive care unit stay, and magnitude of organ dysfunction were monitored prospectively.

MEASUREMENTS AND MAIN RESULTS

Measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoproteins A-I and B, phospholipid, triglyceride, interleukin-6, interleukin-10, soluble interleukin-2 receptor, tumor necrosis factor-alpha, and soluble tumor necrosis factor receptors p55 and p75. Mean serum lipid concentrations were extremely low: total cholesterol, 127 +/- 52 mg/dL; low-density lipoprotein cholesterol, 75 +/- 41 mg/dL; high-density lipoprotein cholesterol, 29 +/- 15 mg/dL. Total, low-density lipoprotein, and high-density lipoprotein cholesterol concentrations and apolipoprotein concentrations inversely correlated with interleukin-6, soluble interleukin-2 receptor, and interleukin-10 concentrations, whereas the triglyceride concentration correlated positively with tumor necrosis factor soluble receptors p55 and p75. Clinical outcomes were related to whether the admission cholesterol concentration was above (n = 56) or below (n = 55) the median concentration of 120 mg/dL. Each of the clinical end points occurred between 1.9- and 3.5-fold more frequently in the very low cholesterol (<120 mg/dL) group. Nine patients (8%) died during the hospitalization. Seven of the nine patients who died had total cholesterol concentrations below the median concentration of 120 mg/dL.

CONCLUSIONS

Low cholesterol and lipoprotein concentrations found in critically ill surgical patients correlate with interleukin-6, soluble interleukin-2 receptor, and interleukin-10 concentrations and predict clinical outcomes.

The inverse association between age and cholesterol level among older patients: the role of poor health status

BACKGROUND

The total cholesterol concentration decreases with age in older people. The reasons for this phenomenon are controversial. This study investigated the hypothesis that poor health status is a determinant of the inverse association between age and cholesterol in older persons.

METHODS

Cross-sectional study of 2,486 (53% women) older medical patients (> or =65 years) admitted at 35 centers of the Gruppo Italiano di Farmacovigilanza nell'Anziano (GIFA) study in Italy. Total cholesterol was measured on the first day after admission to the hospital. Disease burden and comorbidity were assessed by the Charlson index; low serum albumin and iron were considered markers of frailty and poor health.

RESULTS

In men there was a significant, inverse age-cholesterol relationship (-0.97 mg/dl per year, p<0.001). In women the association was nonlinear and cholesterol significantly decreased after the age of 75 (-0.95 mg/dl per year, p<0.005). In multiple linear regression analysis, indicators of poor health accounted for almost two thirds of the crude effect of age on the cholesterol level in both men and women (adjusted coefficients for age were: for men, -0.38 mg/dl per year, p = 0.044; for women after the age of 75, -0.37 mg/dl per year, p = 0.205). The unadjusted probability of having low cholesterol significantly increased with age among men (p for trend <0.005). In multiple logistic regression, indicators of poor health were strongly associated with low cholesterol in both men and women. After adjusting for indicators of poor health, the association between age and low cholesterol in men was no longer present.

CONCLUSION

These findings suggest that the age-dependent reduction of cholesterol often observed in clinical and epidemiologic studies is substantially explained by the effect of poor health status. Low cholesterol in older persons may be a marker of poor health.