Decreased serum level of lipoprotein cholesterol is a poor prognostic factor for patients with severe community-acquired pneumonia that required intensive care unit admission

Prediction of pneumonia hospitalization in adults using health checkup data

Objectives

Community-acquired pneumonia is a common cause of hospitalization, and pneumococcal vaccinations are recommended for high-risk individuals. Although risk factors for pneumonia have been identified, there are currently no pneumonia hospitalization prediction models based on the risk profiles of healthy subjects. This study aimed to develop a predictive model for pneumonia hospitalization in adults to accurately identify high-risk individuals to facilitate the efficient prevention of pneumonia.

Methods

We conducted a retrospective database analysis using health checkup data and health insurance claims data for residents of Kyoto prefecture, Japan, between April 2010 and March 2015. We chose adults who had undergone health checkups in the first year of the study period, and tracked pneumonia hospitalizations over the next 5 years. Subjects were randomly divided into training and test sets. The outcome measure was pneumonia hospitalization, and candidate predictors were obtained from the health checkup data. The prediction model was developed and internally validated using a LASSO logistic regression analysis. Lastly, we compared the new model with comparative models.

Results

The study sample comprised 54,907 people who had undergone health checkups. Among these, 921 were hospitalized for pneumonia during the study period. The c-statistic for the prediction model in the test set was 0.71 (95% confidence interval: 0.69–0.73). In contrast, a comparative model with only age and comorbidities as predictors had a lower c-statistic of 0.55 (95% confidence interval: 0.54–0.56).

Conclusions

Our predictive model for pneumonia hospitalization performed better than comparative models, and may be useful for supporting the development of pneumonia prevention measures.

Can LDL cholesterol be too low? Possible risks of extremely low levels

Following the continuous accumulation of evidence supporting the beneficial role of reducing low-density lipoprotein cholesterol (LDL-C) levels in the treatment and prevention of atherosclerotic cardiovascular disease and its complications, therapeutic possibilities now exist to lower LDL-C to very low levels, similar to or even lower than those seen in newborns and nonhuman species. In addition to the important task of evaluating potential side effects of such treatments, the question arises whether extremely low LDL-C levels per se may provoke adverse effects in humans. In this review, we summarize information from studies of human cellular and organ physiology, phenotypic characterization of rare genetic diseases of lipid metabolism, and experience from clinical trials. Specifically, we emphasize the importance of the robustness of the regulatory systems that maintain balanced fluxes and levels of cholesterol at both cellular and organismal levels. Even at extremely low LDL-C levels, critical capacities of steroid hormone and bile acid production are preserved, and the presence of a cholesterol blood-brain barrier protects cells in the central nervous system. Apparent relationships sometimes reported between less pronounced low LDL-C levels and disease states such as cancer, depression, infectious disease and others can generally be explained as secondary phenomena. Drug-related side effects including an increased propensity for development of type 2 diabetes occur during statin treatment, whilst further evaluation of more potent LDL-lowering treatments such as PCSK9 inhibitors is needed. Experience from the recently reported and ongoing large event-driven trials are of great interest, and further evaluation including careful analysis of cognitive functions will be important.

Lipid testing in infectious diseases: possible role in diagnosis and prognosis

INTRODUCTION

Acute infections lead to significant alterations in metabolic regulation including lipids and lipoproteins, which play a central role in the host immune response. In this regard, several studies have investigated the role of lipid levels as a marker of infection severity and prognosis.

SCOPE OF REVIEW

We review here the role of lipids in immune response and the potential mechanisms underneath. Moreover, we summarize studies on lipid and lipoprotein alterations in acute bacterial, viral and parasitic infections as well as their diagnostic and prognostic significance. Chronic infections (HIV, HBV, HCV) are also considered.

RESULTS

All lipid parameters have been found to be significantly dearranged during acute infection. Common lipid alterations in this setting include a decrease of total cholesterol levels and an increase in the concentration of triglyceride-rich lipoproteins, mainly very low-density lipoproteins. Also, low-density lipoprotein cholesterol, apolipoprotein A1, low-density lipoprotein cholesterol and apolipoprotein-B levels decrease. These lipid alterations may have prognostic and diagnostic role in certain infections.

CONCLUSION

Lipid testing may be of help to assess response to treatment in septic patients and those with various acute infections (such as pneumonia, leptospirosis and others). Diagnostically, new onset of altered lipid levels should prompt the clinician to test for underlying infection (such as leishmaniasis).

Cholesterol levels and long-term rates of community-acquired sepsis

Background

Dyslipidemia is a risk factor for cardiovascular disease, with elevated low-density lipoprotein cholesterol (LDL-C) and decreased high-density lipoprotein cholesterol (HDL-C) recognized as risk factors for acute coronary events. Studies suggest an association between low cholesterol levels and poor outcomes in acute sepsis. We sought to determine the relationship between baseline cholesterol levels and long-term rates of sepsis.

Methods

We used data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, a population-based cohort of 30,239 community-dwelling adults. The primary outcome was first sepsis event, defined as hospitalization for an infection with the presence of ≥2 systemic inflammatory response syndrome criteria (abnormal temperature, heart rate, respiratory rate, white blood cell count) during the first 28 hours of hospitalization. Cox models assessed the association between quartiles of HDL-C or LDL-C and first sepsis event, adjusted for participant demographics, health behaviors, chronic medical conditions, and biomarkers.

Results

We included 29,690 subjects with available baseline HDL-C and LDL-C. There were 3423 hospitalizations for serious infections, with 1845 total sepsis events among 1526 individuals. Serum HDL-C quartile was not associated with long-term rates of sepsis (hazard ratio (HR) (95% CI): Q1 (HDL-C 5–40 mg/dl), 1.08 (0.91–1.28); Q2 (HDL-C 41–49 mg/dl), 1.06 (0.90–1.26); Q3 (HDL-C 50–61 mg/dl), 1.04 (0.89–1.23); Q4, reference). However, compared with the highest quartile of LDL-C, low LDL-C was associated with higher rates of sepsis (Q1 (LDL-C 3–89 mg/dl), 1.30 (1.10–1.52); Q2 (LDL-C 90–111 mg/dl), 1.24 (1.06–1.47); Q3 (LDL-C 112–135 mg/dl), 1.07 (0.91–1.26); Q4, reference).

Conclusion

Low LDL-C was associated with higher long-terms rates of community-acquired sepsis. HDL-C level was not associated with long-term sepsis rates.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1579-8) contains supplementary material, which is available to authorized users.

Nutritional parameters affecting severity of pneumonia and length of hospital stay in patients with pneumococcal pneumonia: a retrospective cross-sectional study

Background

Pneumococcal pneumonia is the most common form of community-acquired pneumonia (CAP). Although a pneumococcal conjugate vaccine has contributed to a reduction in the incidence of pneumococcal pneumonia among older children and adults, no significant decrease in the incidence has been observed among persons aged ≥65 years. A low body mass index and hypoalbuminemia are common in Japanese patients with CAP, but the association of other nutritional parameters with the severity of pneumonia or length of hospital stay in patients with pneumococcal pneumonia is unclear.

Methods

Fifty-seven previously healthy inpatients who presented with pneumococcal pneumonia were divided into two groups: those aged ≥65 years (n = 36) and those aged <65 years (n = 21). Patients’ characteristics (the Confusion, Urea, Respiratory rate, Blood pressure, age >65 years (CURB-65) score), the pneumonia severity index (PSI), and inflammatory and metabolic nutritional parameters were compared between the two groups.

Results

The older group showed significantly lower serum albumin and cholinesterase (ChE) levels. Multivariate linear regression analysis revealed that the PSI was positively correlated with age in both groups. In the younger age group, both the CURB-65 score and PSI showed significant negative correlations with the serum ChE level, and there was a significant negative correlation between the length of stay and serum total cholesterol (T-cho) level. In the older group, the fasting period, lymphocyte count, and age showed significant positive correlations with the length of stay. There was a significant negative correlation between the length of stay and serum albumin level, but no correlation with the serum ChE or T-cho levels, in the older patients.

Conclusions

Our findings suggest that in patients aged <65 years, age and serum ChE and T-cho levels were associated with both the severity of pneumococcal pneumonia and length of stay. In contrast, the length of stay in older patients was associated with multiple factors that differed from those in younger patients. These differences may reflect age-related immunosenescence in older patients and a greater effect of serum ChE and T-cho levels on immunity in younger patients.

Serum Lipoproteins Are Critical for Pulmonary Innate Defense against Staphylococcus aureus Quorum Sensing

Hyperlipidemia has been extensively studied in the context of atherosclerosis, whereas the potential health consequences of the opposite extreme, hypolipidemia, remain largely uninvestigated. Circulating lipoproteins are essential carriers of insoluble lipid molecules and are increasingly recognized as innate immune effectors. Importantly, severe hypolipidemia, which may occur with trauma or critical illness, is clinically associated with bacterial pneumonia. To test the hypothesis that circulating lipoproteins are essential for optimal host innate defense in the lung, we used lipoprotein-deficient mice and a mouse model of Staphylococcus aureus pneumonia in which invasive infection requires virulence factor expression controlled by the accessory gene regulator (agr) operon. Activation of agr and subsequent virulence factor expression is inhibited by apolipoprotein B, the structural protein of low-density lipoprotein, which binds and sequesters the secreted agr-signaling peptide (AIP). In this article, we report that lipoprotein deficiency impairs early pulmonary innate defense against S. aureus quorum-sensing-dependent pathogenesis. Specifically, apolipoprotein B levels in the lung early postinfection are significantly reduced with lipoprotein deficiency, coinciding with impaired host control of S. aureus agr-signaling and increased agr-dependent morbidity (weight loss) and inflammation. Given that lipoproteins also inhibit LTA- and LPS-mediated inflammation, these results suggest that hypolipidemia may broadly impact posttrauma pneumonia susceptibility to both Gram-positive and -negative pathogens. Together with previous reports demonstrating that hyperlipidemia also impairs lung innate defense, these results suggest that maintenance of normal serum lipoprotein levels is necessary for optimal host innate defense in the lung.