Blood Cholesterol Level and Risk of Stroke in Community-based or Worksite Cohort Studies: A Review of Japanese Cohort Studies in the Past 20 years

Associations between low-density lipoprotein cholesterol and haemorrhagic stroke

OBJECTIVE

To investigate the associations between the blood concentrations of low-density lipoprotein cholesterol (LDL-C) and the clinical features of haemorrhagic stroke.

METHODS

This study analysed the data from patients with acute haemorrhagic stroke at a comprehensive stroke centre from 2013 to 2018. Patients were stratified into three groups according to their baseline LDL-C levels: < 70, 70 to < 100 and ≥ 100 mg/dL. We used multivariate logistic regression models to analyse the associations between LDL-C and the risks of having severe neurological deficits (National Institute Health Stroke Scale [NIHSS] scores ≥ 15) and unfavourable outcomes (modified Rankin Scale [mRS] scores>2) at discharge.

RESULTS

Six-hundred and six patients were analysed. Their median age was 58 years. Among the patients, 75 (12%) patients had LDL-C levels < 70 mg/dL, 194 (32%) patients had LDL-C levels between 70 to < 100 mg/dL and the other 337 (56%) patients had LDL-C levels ≥ 100 mg/dL. Patients with higher LDL-C levels were less likely to suffer severe neurological deficits (LDL-C: 70 to < 100 vs. < 70 mg/dL, adjusted odds ratio [OR]: 0.29, 95% CI: 0.15-0.57; LDL-C: ≥ 100 vs. < 70 mg/dL, adjusted OR = 0.27, 95% CI: 0.15-0.51) and to have unfavourable outcomes at discharge (LDL-C: 70 to < 100 vs. < 70 mg/dL, adjusted OR = 0.50, 95% CI: 0.29-0.87 and LDL-C: ≥ 100 vs. < 70 mg/dL, adjusted OR = 0.46, 95% CI: 0.28-0.78).

CONCLUSIONS

An LDL-C level < 70 mg/dL was independently associated with severe neurological deficits of haemorrhagic stroke and may increase the risks of unfavourable outcomes at discharge.

The Association Between Low Serum Cholesterol and Non-Cardiovascular Mortality among Italian Males and Females: A Nine- Year Prospective Cohort Ctudy

Background: No study to date provides evidence suggesting that lower cholesterol is associated with excess death in non-cardiovascular disease (NCVD). This study aimed to determine the association between low cholesterol level and NCVD mortality. Methods: A nine-year cohort study was conducted on 3,079 male and 26,005 female Italians aged 20-69 years old. The Cox proportional hazard models implied a hazard ratio with 95% confidence interval for association. Results: Among males, there were significant inverse associations between the lowest cholesterol decile (< 160mg/dl) hazard ratio and all-cause deaths and non-cardiovascular deaths, 1.50 (1.19-1.89) and 2.06 (1.54-2.74), respectively. Among females, there was a significant inverse association of lowest and fourth cholesterol deciles, 1.53 (1.01-2.34); 1.52 (1.06-2.18) hazard ratio for all-cause deaths and risk for non-cardiovascular deaths in the same deciles 1.52 (0.91-2.50); 1.78 (1.16-2.71), respectively. Remarkably, in depth analysis for NCVD, found significant inverse associations hazard of cholesterol <160 mg/dl for cancer, non-cancer liver dysfunction (NCLD), other non-cancer-non- CVD in males and only NCLD death was significant in females. Conclusion: Among males, there were significant inverse hazard associations between the lowest cholesterol decile and all-cause and non-CVD deaths . Among females, there were significant inverse hazard associations of lowest and fourth cholesterol decile for all-cause and also risk first and fourth deciles for non-CVD mortality.

Is low cholesterol a risk factor for cancer mortality?

Although a large number of studies have shown the associations of high plasma lipid profile levels with cancer, few studies demonstrate the association between low serum cholesterol (<160 mg/dl) and risk for cancer mortality. The aim of this study was to determine the association of low serum cholesterol level as a risk factor for mortality in cancer. The prospective cohort studies were conducted on 19 of 52 cohort studies including 30 179 male and 26 005 female participants who were followed up for 9 years. Cox proportion hazard model was applied to analyze these data. The associations are presented as hazard ratios (HRs) with 95% confidence intervals (CI). The statistical package for the social sciences software was used for analysis. The multivariate analysis results showed risk associations with low serum cholesterol for the first decile among male participants (cancer: HR=1.52, 95% CI: 1.06-2.18; noncancer liver dysfunction: HR=10.73, 95% CI: 3.74-30.18) and female participants (cancer: HR=1.03, 95% CI: 0.52-2.05; noncancer liver dysfunction: HR=25.8, 95% CI: 3.09-217.70). Furthermore, in the second decile, this association among male patients (noncancer liver dysfunction: HR=3.73, 95% CI: 1.16-11.95) had a statistically significant result. For the remaining deciles in both sexes, cancer and noncancer liver dysfunction has some risk or protective association, although not significant. Findings of this study indicated an inverse association between low serum cholesterol and cancer and noncancer liver dysfunction mortality.

Simvastatin pretreatment ameliorates t-PA-induced hemorrhage transformation and MMP-9/TIMP-1 imbalance in thromboembolic cerebral ischemic rats

Background: The use of thrombolysis with tissue-plasminogen activator (t-PA) in patients with acute ischemic stroke (AIS) is limited by increased levels of matrix metalloproteinase-9 (MMP-9) and by the increased risk of hemorrhagic transformation (HT). In this study, we investigated the effects of simvastatin pretreatment on t-PA-induced MMP-9/tissue inhibitor of metalloproteinase-1 (TIMP-1) imbalance and HT aggravation in a rat AIS model. Methods: The rat AIS model was established by autologous blood emboli. Two weeks before surgery, rats were pretreated with simvastatin (60 mg/kg/d), and three hours after surgery, t-PA (10 mg/kg) was administered. MMP-9 and TIMP-1 levels in the infarcted zone and plasma were evaluated by Western blot analysis and ELISA; the level of HT was quantified by determining the hemoglobin content. RhoA activation was determined to clarify the potential effect. Results: The results suggested that pretreatment with simvastatin suppressed the increase in t-PA-induced MMP-9 levels and neutralized the elevated MMP-9/TIMP-1 ratio, but had no effect on TIMP-1 levels. Thrombolysis with t-PA after ischemia improved neurological outcome, but increased intracranial hemorrhage. Moreover, t-PA-induced HT aggravation was reduced by simvastatin pretreatment. In addition, we showed that t-PA-induced activation of RhoA was suppressed by simvastatin, and that t-PA-induced MMP-9/TIMP-1 imbalance and hemorrhage was reduced by Rho kinases (ROCK) inhibitor Y-27632. Conclusion: In this study, we showed that simvastatin pretreatment ameliorated t-PA-induced HT and MMP-9/TIMP-1 imbalance, and demonstrated that the RhoA/ROCK pathway was implicated.

Association between polymorphisms in the APOB gene and hyperlipidemia in the Chinese Yugur population

We investigated the influence of apolipoprotein B gene (APOB) variants on the risk of hyperlipidemia (HL) in 631 middle-aged and elderly members of the Chinese Yugur population (HL, n=336; normolipidemia, n=295). APOB polymorphisms were identified using mass spectrometry, and five single nucleotide polymorphisms (rs1042034, rs2163204, rs512535, rs676210, and rs679899) and serum lipids were further analyzed. rs1042034 and rs676210 were significantly associated with HL (P<0.05). Compared with the GG or AA genotype, individuals with AG and AG+AA in rs1042034 and with AG and AG+GG in rs676210 had a 1.67-fold (95%CI=1.20-2.33),1.63-fold (95%CI=1.19-2.24), 1.72-fold (95%CI=1.24-2.40), and 1.67-fold (95%CI=1.21-2.291) increased risk of high HL, respectively. rs2163204 was in strong linkage disequilibrium with rs1042034, rs676210, and rs679899, and strong disequilibrium was observed between rs1042034 and rs676210 (D'>0.9). Compared with the GTGAA haplotype, haplotypes ATGGA and ATAGG were more strongly associated with HL [odds ratio (OR)=1.46, 95%CI=0.02-2.11; OR=1.63, 95%CI=1.03-2.60, respectively]. The risk factors age (P=0.008), body mass index (P<0.0001), GA+GG genotype in rs676210 (P=0.009), and alcohol consumption (P=0.056) contributed strongly to HL development. The A allele of rs1042034 and the G allele of rs676210 may thus predispose middle-aged and elderly members of the Chinese Yugur population to HL in combination with other genetic or nutritional factors, and could be used as new genetic markers for HL screening.

Improvement of Triglyceride Levels through the Intake of Enriched-β-Conglycinin Soybean (Nanahomare) Revealed in a Randomized, Double-Blind, Placebo-Controlled Study

Soybean is recognized as a beneficial food with various functional components, such as β-conglycinin, which improves lipid metabolism. We evaluated the effects of the β-conglycinin-rich soybean Nanahomare on triglyceride (TG) levels. In this randomized, double-blind, placebo-controlled study, we divided 134 adult subjects into test and placebo groups that consumed processed food containing enriched-β-conglycinin soybean or low-β-conglycinin soybean. Hematological tests and body composition measurements were performed at weeks 0 (baseline), 4, 8, and 12 of the study period. TG levels significantly decreased in the test group compared with the placebo group at weeks 4 (change from baseline to week 4, placebo: 0.27 ± 44.13 mg/dL, test: -20.31 ± 43.74 mg/dL, p = 0.035) and 12 (change from baseline to week 12, placebo: -0.14 ± 65.83 mg/dL, test: -21.30 ± 46.21 mg/dL, p = 0.041). In addition, among subjects whose baseline TG levels were ≥100 mg/dL, the levels significantly improved in the test group at weeks 4 (p = 0.010) and 12 (p = 0.030), whereas the levels were not different between the test and placebo groups among those whose baseline levels were <100 mg/dL. These results suggest that the ingestion of enriched-β-conglycinin soybean improves serum TG levels.

Evidence-based assessment of lipoprotein(a) as a risk biomarker for cardiovascular diseases - Some answers and still many questions

The present article is aimed at outlining the current state of knowledge regarding the clinical value of lipoprotein(a) (Lp(a)) as a marker of cardiovascular disease (CVD) risk by summarizing the results of recent clinical studies, meta-analyses and systematic reviews. The literature supports the predictive value of Lp(a) on CVD outcomes, although the effect size is modest. Lp(a) would also appear to have an effect on cerebrovascular outcomes, however the effect appears even smaller than that for CVD outcomes. Consideration of apolipoprotein(a) (apo(a)) isoforms and LPA genetics in relation to the simple assessment of Lp(a) concentration may enhance clinical practice in vascular medicine. We also describe recent advances in Lp(a) research (including therapies) and highlight areas where further research is needed such as the measurement of Lp(a) and its involvement in additional pathophysiological processes.

The Relationship between Very High Levels of Serum High-Density Lipoprotein Cholesterol and Cause-Specific Mortality in a 20-Year Follow-Up Study of Japanese General Population

AIMS

There is no community-based cohort study to examine the effect of very high level of high-density lipoprotein cholesterol (HDL-C) on coronary heart disease (CHD) and other cause-specific mortality. Therefore, we investigated the relationship between HDL-C including very high level and cause-specific mortality in a 20-year cohort study of the representative sample of Japanese.

METHODS

We followed 7,019 individuals from the Japanese general population (2,946 men and 4,073 women). We defined HDL-C levels as follow: low (HDL-C ＜1.04 mmol/L), reference (1.04-1.55 mmol/L), high (1.56-2.06 mmol/L), very high (≥2.07 mmol/L). The multivariate adjusted hazard ratio (HR) for all-cause or cause-specific mortality was calculated using a Cox proportional hazards model adjusted for other traditional risk factors.

RESULTS

During follow-up, we observed 1,598 deaths. No significant association was observed between HDL-C and all-cause mortality. Serum HDL-C also showed no association with stroke. In contrast, the risk for CHD among high HDL-C was lower than reference, HRs were 0.51 [95% confidence interval (CI): 0.21-1.23] in men, 0.33 (95% CI: 0.11-0.95) in women, and 0.41 (95% CI: 0.21-0.81) when men and women were combined. However, very high HDL-C did not show significant association with CHD and other cause-specific mortality.

CONCLUSIONS

HDL-C was not associated with all-cause and stroke mortality. In contrast, high serum HDL-C levels, at least up to 2.06 mmol/L, were protective against CHD, although further high levels were not. However, sample size of cause-specific death in very high HDL-C group was not enough even in this 20-year follow-up of 7,019 Japanese; larger cohort studies should be warranted.

Blood pressure, low-density lipoprotein cholesterol, and incidences of coronary artery disease and ischemic stroke in Japanese: the Suita study

BACKGROUND

Blood pressure (BP) and low-density lipoprotein cholesterol (LDL-C) are risk factors for coronary artery disease (CAD) and ischemic stroke. However, the hazards of their coexistence are not fully understood in Asian populations. We investigated whether the relationship between BP and cardiovascular disease (CVD) outcomes are modified by LDL-C level in a Japanese population.

METHODS

Individuals aged 30-79 years (n = 5,151) were classified into 6 groups according to LDL-C levels (<140 and ≥140mg/dL or lipid medication) and BP levels (optimal BP, prehypertension, and hypertension; reference: low LDL-C and optimal BP). Hazard ratios (HRs) were calculated after adjusting for age, high-density lipoprotein cholesterol, diabetes, smoking status, and alcohol consumption. The effect modification of LDL-C on BP-CVD association was assessed using likelihood ratio tests.

RESULTS

There were 264 CAD and 215 ischemic stroke events during 13 years of follow-up. With low LDL-C, the HRs of prehypertension and hypertension for CAD were 2.01 and 4.71, respectively. Similar trends of HRs were observed with high LDL-C (optimal BP = 2.09, prehypertension = 3.45, hypertension = 5.94). However, the HRs for ischemic stroke did not differ between normal and high LDL-C levels at the same BP level. The apparent effect modification of LDL-C was not observed in the BP-CVD association in either CAD (P = 0.48) or ischemic stroke (P = 0.39).

CONCLUSIONS

The HRs for CAD in prehypertensive and hypertensive groups were higher than those in the optimal BP group at the same LDL-C levels in a Japanese population; however, there was no statistical effect modification of LDL-C on the BP-CAD association.