Mildly elevated serum bilirubin levels are negatively associated with carotid atherosclerosis among elderly persons

High-normal serum bilirubin decreased the risk of lower limb atherosclerosis in type 2 diabetes: a real-world study

BACKGROUND

Bilirubin has been found to protect against overt atherosclerotic diseases, but to date, few studies have investigated the effects of bilirubin especially within the normal range on lower limb atherosclerosis. Therefore, we aimed to assess the associations of bilirubin within normal limits including total bilirubin (TB), conjugated bilirubin (CB) and unconjugated bilirubin (UCB) with lower limb atherosclerosis in Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

7284 T2DM patients with normal levels of serum bilirubin were included in this cross-sectional, real-world study. Patients were divided into quintiles by TB levels (< 8.7, 8.7-10.19, 10.20-11.99, 12-13.99, > 13.99 µmol/L). Lower limb ultrasonography was conducted to detect lower limb plaque and stenosis. The association between serum bilirubin and lower limb atherosclerosis was explored by multiple logistic regression.

RESULTS

A remarkable decrease in the prevalence of lower limb plaque (77.5, 75.3, 70.7, 71.7 and 67.9%) and stenosis (21.1, 17.2, 13.3, 13.0 and 12.0%) was observed across the TB quintiles. Multivariable regression analysis showed that serum TB levels were negatively correlated with higher risks of lower limb plaque and stenosis, both as a continuous variable [OR (95%CI): 0.870 (0.784-0.964), p = 0.008 for plaque; and 0.835 (0.737-0.946), p = 0.005 for stenosis] and as categorized in quintiles (p = 0.015 and 0.016 for plaque and stenosis). Interestingly, serum CB levels were only negatively correlated with lower limb stenosis [OR (95%CI): 0.767 (0.685-0.858), p < 0.001], whereas serum UCB levels were only negatively associated with lower limb plaque [ OR (95%CI): 0.864 (0.784-0.952), p = 0.003] after a fully-adjusted analysis. Furthermore, serum CRP was significantly decreased across the TB quintiles and negatively associated with serum TB (r = -0.107, p < 0.001), CB (r = -0.054, p < 0.001), and UCB (r = -0.103, p < 0.001).

CONCLUSIONS

High-normal serum bilirubin levels were independently and significantly related to reduced risks of lower limb atherosclerosis in T2DM patients. Furthermore, serum bilirubin levels including TB, CB and UCB were inversely correlated with CRP. These results suggested that higher-normal serum bilirubin may exhibit an anti-inflammatory and protective effect against lower limb atherosclerotic progression in T2DM subjects.

Low-normal serum unconjugated bilirubin levels are associated with late but not early carotid atherosclerotic lesions in T2DM subjects

AIMS

We aimed to examine the association of serum unconjugated bilirubin (UCB) within normal limits with carotid atherosclerosis in Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional, real-world study was performed in 8,006 hospitalized T2DM patients including 4,153 men and 3,853 women with normal UCB. The subjects were stratified into quintiles based on serum UCB levels (<6.2, 6.2-7.9, 8.0-8.9, 9.0-10.9, and >10.9 μmol/l, respectively). Carotid atherosclerotic lesions detected by ultrasonography, including carotid intima-media thickness (CIMT), carotid plaque, and stenosis, were compared among the five groups. The associations of serum UCB levels and quintiles with carotid atherosclerotic lesions were also determined by multiple logistic regression.

RESULTS

The prevalence of carotid plaque (55.3%, 49.5%, 47.4%, 43.8%, and 37.5%, respectively; p < 0.001 for trend) and stenosis (15.2%, 12.2%, 9.1%, 7.7%, and 5.4%, respectively; p < 0.001 for trend) was progressively lower across the UCB quintiles even after adjusting for age, sex, and duration of diabetes. Results of a fully adjusted multiple logistic regression analysis revealed that serum UCB levels and quintiles were significantly associated with carotid plaque and stenosis. Compared with the subjects in the lowest UCB quintile, the risk of carotid plaque decreased by 25.5%, 28.7%, 33.5%, and 42.8%, and that of carotid stenosis by 24.6%, 37.4%, 44.9%, and 47.3%, respectively, in those from the second to highest UCB quintiles. High serum UCB within the normal range was a protective factor against carotid plaque [odds ratio (OR) 0.810, 95% confidence interval (CI) 0.747-0.878; p < 0.001] and stenosis [OR 0.722, 95% CI 0.647-0.805; p < 0.001]. However, no significant association was observed between serum UCB and CIMT in T2DM patients. Furthermore, C-reactive protein (CRP) levels were significantly higher in the subjects with carotid atherosclerosis than in those without carotid atherosclerosis and clearly decreased across the UCB quintiles.

CONCLUSIONS

Serum UCB within normal limits is inversely associated with late carotid atherosclerotic lesions including carotid plaque and stenosis but not CIMT, an early carotid atherosclerotic lesion in T2DM patients. High-normal UCB may be protective against carotid atherosclerosis by its anti-inflammation effect, which was indicated by significantly decreased CRP levels from the lowest to highest UCB quintiles.

Mildly decreased preoperative bilirubin levels are associated with infections after shoulder and knee arthroplasty

Increasing numbers of arthroplasties are also accompanied by postoperative infections. The main purpose was to evaluate preoperative serum bilirubin levels between patients with and without infections after shoulder and knee arthroplasties. For this retrospective case-control single-center study, a total of 108 patients were extracted from a prospectively collected database. Eighteen patients with infections after shoulder (n = 8) and knee (n = 10) arthroplasty were matched by age, gender, and implant type in a 1:5-scenario to 90 patients (40 shoulders and 50 knees) without postoperative infection. Demographic data, preoperative blood parameters, and postoperative infection-related outcomes were evaluated. Total bilirubin was the only preoperative parameter significantly different between the infection (8.21 ± 3.25 μmol/L or 0.48 ± 0.19 mg/dL) and noninfection (10.78 ± 4.62 μmol/L or 0.63 ± 0.27 mg/dL; P = .014) group, while C-reactive protein and other liver parameters were similar between the groups. Significantly more controls (92.1%) had preoperative bilirubin levels above 8.72 μmol/L or 0.51 mg/dL than cases (7.9%; P = .007). The 5-year infection survival-rate was 65.6% for patients with preoperative bilirubin levels < 8.72 μmol/L or < 0.51 mg/dL and 91.2% with ≥ 8.72 μmol/L or ≥ 0.51 mg/dL. Mildly decreased preoperative bilirubin levels with a cutoff at 8.72 μmol/L or 0.51 mg/dL were significantly associated to patients with infections after shoulder and knee arthroplasty. There were no differences in other blood parameters or comorbidities between patients with infections and their matched-controls.

Atherosclerosis prediction by microarray-based DNA methylation analysis

Using a series of DNA methylation analysis, pathogenesis was investigated to identify the specific DNA methylation markers for diagnosing atherosclerosis. Firstly, with the chip platform of Illumina Human Methylation 450 BeadChip, a total of 1,458 CpGs, covering 971 differential methylated genes were extracted with stringent filtering criteria. Secondly, hierarchical clustering as a heat map was used to check on the dependability of differential methylated genes. Thirdly, the related GO terms and pathways were enriched by up- and down-methylated genes, respectively, after verifying the capacity of these differential methylated genes to distinguish between atherosclerosis and healthy controls. In total, 971 differential DNA methylated genes were identified (1,458 CpGs). Several important function regions were also identified, including cell adhesion, PI3K-Akt signaling pathway and transcription from RNA polymerase II promoter. This study indicates that patients with atherosclerosis have high levels of DNA methylation, which is promising for early diagnosis and treatment of atherosclerosis.

Association between serum bilirubin and asymptomatic intracranial atherosclerosis: results from a population-based study

INTRODUCTION

The effects of bilirubin on asymptomatic intracranial atherosclerosis (aICAS) remain uncertain.

OBJECTIVES

To investigate the association between bilirubin and aICAS in rural-dwelling Chinese people.

METHODS

This population-based study included 2013 participants from the Kongcun Town Study, which aimed to investigate the prevalence of aICAS in people aged ≥ 40 years who were free of stroke and hepatic and gall disease history. Baseline data were collected via interviews, clinical examinations, and laboratory tests. Total bilirubin (Tbil), direct bilirubin (Dbil), and indirect bilirubin (Ibil) levels were divided into high-concentration group and low-concentration group, respectively. We diagnosed aICAS and moderate-to-severe aICAS (m-saICAS) (≥ 50% stenosis) by integrating transcranial Doppler ultrasound with magnetic resonance angiography. The association between bilirubin and aICAS, as well as m-saICAS, was analyzed using logistic regression.

RESULTS

Of the 2013 participants, those in the high-concentration group of Tbil (odds ratio (OR), 0.50; 95% confidence interval (CI), 0.42-0.87), Dbil (OR 0.60, 95%CI 0.41-0.87), and Ibil (OR 0.67; 95%CI 0.47-0.97) had a lower risk of aICAS than those in the low-concentration group after adjusting all confounders. The high concentrations of Tbil, Dbil, and Ibil were also negatively associated with m-saICAS. After stratification according to age, Tbil, Dbil, and Ibil were significantly negatively associated with aICAS among participants aged ≥ 60 years.

CONCLUSION

Tbil, Dbil, and Ibil might be independent protective factors for aICAS and moderate-to-severe aICAS in rural-dwelling Chinese people, especially among older participants aged ≥ 60 years.

Brief Report: Hyperbilirubinemia Is Associated With a Decreased Risk of Carotid Atherosclerosis in HIV-Infected Patients on Virological Suppression

OBJECTIVE

To investigate the association between total, direct, and indirect bilirubin and the presence of carotid lesions in a large sample of HIV-1-infected patients on virological suppression.

DESIGN

Retrospective study on adult HIV-1-infected patients, with a carotid ultrasound (CUS) examination performed between January 2008 and August 2016, with HIV-RNA <50 copies per milliliter at CUS and without previous cardiovascular events.

METHODS

Intima media thickness was measured in 4 segments: carotid common artery and bifurcation on the left and right sides. Carotid lesion was defined as an intima media thickness ≥1.5 mm in ≥1 region at CUS. Patients were classified as: normal if all bilirubin values before CUS were below the upper normal limit and with hyperbilirubinemia if ≥1 bilirubin value above upper normal limit before CUS was recorded. Multivariate logistic regression was used to determine whether hyperbilirubinemia showed association with the presence of ≥1 carotid lesion, after adjusting for confounding factors.

RESULTS

Overall, 903 patients were evaluated, 511 with ≥1 and 392 without carotid lesions. At multivariate analysis, total [adjusted odds ratio (95% confidence interval) 0.57 (0.36 to 0.90), P = 0.016] and indirect hyperbilirubinemia before CUS [adjusted odds ratio (95% confidence interval) 0.62 (0.40 to 0.97), P = 0.036] were associated with a lower risk of carotid lesions in addition to younger age, negative hepatitis C virus antibodies, higher nadir CD4, lower low-density lipoprotein cholesterol, higher high-density lipoprotein cholesterol, lower triglycerides, and no use of statin; no effect of atazanavir treatment on carotid lesions was detected.

CONCLUSIONS

In HIV-1-treated patients, total or indirect hyperbilirubinemia was likely associated with the absence of carotid lesions.

Relationship Between Total Serum Bilirubin Levels and Carotid and Femoral Atherosclerosis in Familial Dyslipidemia

Objective—

Bilirubin is a potent antioxidant that has been inversely related to cardiovascular disease. There is little information on serum total bilirubin (TB) in relation to atherosclerosis in familial dyslipidemia. We assessed the association between TB and carotid and femoral atherosclerosis in this high-risk group.

Approach and Results—

We evaluated 464 individuals with familial dyslipidemia (56% men; median age, 48 years), 322 with familial hypercholesterolemia, and 142 with familial combined hyperlipidemia. Carotid and femoral arteries were imaged bilaterally with a standardized ultrasonographic protocol. Mean and maximum intima-media thickness and plaque presence (≥1.2 mm) and height were recorded. Cross-sectional associations between TB and atherosclerosis variables were investigated in multivariable-adjusted models, including lipid values and hypolipidemic drug use. Inflammatory markers (C-reactive protein, total leukocyte count, and lipoprotein[a]) were also determined. Increasing TB levels were associated with decreasing intima-media thickness of all carotid segments ( P <0.05, all). TB also related to carotid plaque, present in 78% of individuals, and to plaque burden (≥3 plaques), with odds ratios (95% confidence interval) 0.59 (0.36–0.98) and 0.57 (0.34–0.96) for each increase of 0.5 mg in TB, respectively. Findings were confirmed in a validation cohort of 177 subjects with nonfamilial dyslipidemia. Only the familial combined hyperlipidemia group, with higher inflammation-related markers, showed an inverse association between TB and femoral plaque height (β=−0.183; P =0.030).

Conclusions—

TB was inversely and independently associated with carotid plaque burden in familial and nonfamilial dyslipidemia. These findings support the use of TB as a biomarker of atherosclerosis in this high-risk group.

Associations between serum bilirubin levels and essential trace elements status in an adult population

OBJECTIVE

This paper aims to evaluate the relations between serum bilirubin and essential trace elements in an adult population.

RESULTS

Demographic and clinical data were stratified according to the median of serum bilirubin concentrations (50th percentiles). There were statistical differences in regarding with age, body mass index, white blood count, hemoglobin, mean corpuscular hemoglobin, alanine aminotransferase, creatinine, high-sensitivity C-reactive protein, iron, zinc and copper. Studying the correlation of serum bilirubin levels with iron, zinc, copper and high-sensitivity C-reactive protein, we found positive correlations for iron and zinc, and negative correlations for high-sensitivity C-reactive protein and copper in whole participants. Similar results of correlation analysis were repeated when the further analyses were performed separately for subjects with high and low serum bilirubin concentrations. Similar results were also observed in gender-based stratified analysis. Multiple linear regression analysis revealed that serum bilirubin levels were independently correlated with serum iron, zinc and copper.

MATERIALS AND METHODS

The cross-sectional study involved 264 healthy subjects.

CONCLUSIONS

The current study demonstrated that serum bilirubin within the reference range is correlated with iron, zinc and copper in an adult population, regardless of potential confounders.

Handgrip Strength Is Positively Associated with Mildly Elevated Serum Bilirubin Levels among Community-Dwelling Adults

Handgrip strength (HGS) is a useful measure of health-related quality of life and general muscle strength. Serum total bilirubin (T-B) may present potential beneficial effects in preventing oxidative changes which are associated with a risk of metabolic syndrome and the development of cardiovascular disease. Limited information is available regarding whether HGS is an independent confounding factor for serum T-B. The study participants were 214 men aged 71 ± 8 (mean ± standard deviation) years and 302 women aged 71 ± 7 years that were enrolled consecutively from among paticipants aged ≥ 50 years through an annual check-up process. We evaluated the relationship between serum T-B and confounding factors within each sex. HGS related significantly with serum T-B in both men (r = 0.156, p = 0.023) and women (r = 0.173, p = 0.003). Multiple linear regression analysis showed that in men, HGS (β = 0.173) as well as smoking status (β = -0.147), exercise habit (β = 0.138), low-density lipoprotein cholesterol (β = 0.146), and hemoglobin A1c (HbA1c) (β = -0.198) were significantly and independently associated with serum T-B. In women, HGS (β = 0.159) as well as smoking status (β = -0.116), high-density lipoprotein cholesterol (β = 0.159), and HbA1c (β = -0.161) were significantly and independently associated with serum T-B. Multivariate-adjusted serum T-B levels were significantly lower in subjects with the lowest HGS level in both sexes. Increased HGS is strongly associated with increased serum T-B, independent of confounding factors in both sexes.

Differential impact of serum total bilirubin level on cerebral atherosclerosis and cerebral small vessel disease

BACKGROUND

A low serum total bilirubin (T-bil) level is associated with an increased risk of atherosclerosis. However, the differential impact of the serum T-bil level on cerebral atherosclerosis and cerebral small vessel disease (SVD) is still unclear.

METHODS

We evaluated serum T-bil levels from 1,128 neurologically healthy subjects. Indices of cerebral atherosclerosis (extracranial arterial stenosis [ECAS] and intracranial arterial stenosis [ICAS]), and indices of SVD (silent lacunar infarct [SLI], and moderate-to-severe white matter hyperintensities [msWMH]) were evaluated by the use of brain magnetic resonance imaging (MRI) and MR angiography.

RESULTS

In logistic regression analysis after adjusting for confounding variables, subjects within middle T-bil (odds ratio [OR]: 0.63; 95% CI: 0.41-0.97) and high T-bil tertiles (OR: 0.54; 95% CI: 0.33-0.86) showed a lower prevalence of ECAS than those in a low T-bil tertile. Although subjects with a high T-bil tertile had a lower prevalence of ICAS than those with a low T-bil tertile, the statistical significance was marginal after adjusting for confounding variables. There were no significant differences in the proportions of subjects with SLI and msWMH across serum T-bil tertile groups.

CONCLUSIONS

The serum T-bil level is negatively associated with cerebral atherosclerosis, especially extracranial atherosclerosis, but not with SVD.

Higher direct bilirubin levels during mid-pregnancy are associated with lower risk of gestational diabetes mellitus

Bilirubin concentrations have been recently reported to be negatively associated with type 2 diabetes mellitus. We examined the association between bilirubin concentrations and gestational diabetes mellitus. In a prospective cohort study, 2969 pregnant women were recruited prior to 16 weeks of gestation and were followed up until delivery. The value of bilirubin was tested and oral glucose tolerance test was conducted to screen gestational diabetes mellitus. The relationship between serum bilirubin concentration and gestational weeks was studied by two-piecewise linear regression. A subsample of 1135 participants with serum bilirubin test during 16-18 weeks gestation was conducted to research the association between serum bilirubin levels and risk of gestational diabetes mellitus by logistic regression. Gestational diabetes mellitus developed in 8.5 % of the participants (223 of 2969). Two-piecewise linear regression analyses demonstrated that the levels of bilirubin decreased with gestational week up to the turning point 23 and after that point, levels of bilirubin were increased slightly. In multiple logistic regression analysis, the relative risk of developing gestational diabetes mellitus was lower in the highest tertile of direct bilirubin than that in the lowest tertile (RR 0.60; 95 % CI, 0.35-0.89). The results suggested that women with higher serum direct bilirubin levels during the second trimester of pregnancy have lower risk for development of gestational diabetes mellitus.

Mildly elevated serum total bilirubin is negatively associated with hemoglobin A1c independently of confounding factors among community-dwelling middle-aged and elderly persons

Abnormally high glycated hemoglobin (Hb) (HbA1c) is significantly associated with oxidative stress and an increased risk of cardiovascular disease (CVD). Serum total bilirubin (T-B) may have a beneficial role in preventing oxidative changes and be a negative risk factor of CVD. Limited information is available on whether serum T-B is an independent confounding factor of HbA1c. The study subjects were 633 men aged 70 ± 9 (mean ± standard deviation (SD)) years and 878 women aged 70 ± 8 years who were enrolled consecutively from among patients aged ≥40 years through a community-based annual check-up process. We evaluated the relationship between various confounding factors including serum T-B and HbA1c in each gender. Multiple linear regression analysis pertaining to HbA1c showed that in men, serum T-B (β = -0.139) as well as waist circumference (β = 0.099), exercise habit (β = 0.137), systolic blood pressure (SBP) (β = 0.076), triglycerides (β = 0.087), and uric acid (β = -0.123) were significantly and independently associated with HbA1c, and in women, serum T-B (β = -0.084) as well as body mass index (β = 0.090), smoking status (β = -0.077), SBP (β = 0.117), diastolic blood pressure (DBP) (β = -0.155), low-density lipoprotein cholesterol (β = 0.074), prevalence of antidyslipidemic medication (β = 0.174), and uric acid (β = 0.090) were also significantly and independently associated with HbA1c. Multivariate-adjusted serum HbA1c levels were significantly high in subjects with the lowest serum T-B levels in both genders. Serum T-B is an independent confounding factor for HbA1c among community-dwelling middle-aged and elderly persons.

Relationship between Serum Bilirubin and Left Ventricular Hypertrophy in Patients with Essential Hypertension

BACKGROUND

Prospective studies have found low bilirubin levels were an important predictive factor of cardiovascular events. However, few have yet investigated possible association between serum bilirubin level and LVH in essential hypertension. The aim of the present study was to evaluate the relationship between serum bilirubin levels with LVH in newly diagnosed hypertension patients.

METHODS

The present study evaluated the relationship between serum total bilirubin level and left ventricle hypertrophy (LVH) in newly diagnosed hypertensive patients with a sample size of 344. We divided subjects into LVH group (n=138) and non-LVH group (n=206). Physical examination, laboratory tests and echocardiography were conducted. The multivariate logistic regression model was used to verify the independent association between RDW and LVH.

RESULTS

Our results found that patients with LVH had lower bilirubin levels than non-LVH ones. Stepwise multiple linear regression analysis showed total bilirubin level (B=-0.017, P=0.008) was negatively associated with left ventricle mass index (LVMI) even adjusting for some confounders. The multiples logistic regression found total bilirubin level was independently related with of LVH, as a protective factors (OR=0.91, P=0.010).

CONCLUSION

As a routine and quick laboratory examination index, serum bilirubin may be treated as novel marker for evaluating LVH risk in hypertensive patients. Cohort study with larger sample size are needed.

Association between serum bilirubin and estimated glomerular filtration rate among elderly persons

Chronic kidney disease (CKD) is a major public health problem. However, few studies have examined the significance of serum bilirubin as a risk factor for the development of CKD in the general Japanese population. The subjects comprised 413 men (mean age: 79±9 years; (range, 60-100 years) and 637 women (mean age: 81±8 years; range, 60-106 years) who visited the medical department of Seiyo Municipal Nomura Hospital. We examined the relationship between increased serum bilirubin and renal function that was evaluated by estimated glomerular filtration rate (eGFR) using CKD-EPI equations modified by a Japanese coefficient. Stepwise multiple regression analysis with eGFR as the objective variable, and adjusted risk factors as the explanatory variables, showed that serum bilirubin (β = 0.11, P<0.001) was significantly and independently associated with eGFR, in addition to gender, age, prevalence of antihypertensive medication, triglycerides, prevalence of antidiabetic medication, and serum uric acid. Compared with stages 1+2 (eGFR ≥60.0 ml/min/1.73 m2), mean multivariate-adjusted odds ratio {95% (confidence interval (CI)} for hypobilirubinemia (first quartile, <0.52 mg/dL) was 3.52 (range: 1.88-6.59). Next, to control potential confounding factors, data were further stratified by gender, age, medication (antihypertensive, antidyslipidemic, and antidiabetic agents), and prevalence of cardiovascular disease. The standardized coefficient for eGFR was significant in both groups, and there was no interaction between the groups. Our data demonstrated an independent positive association between serum bilirubin and eGFR in both genders. Low serum bilirubin level would be useful as a potential risk factor for renal function.