Hypertension in East Asia

[Trends and challenges in clinical research on cerebral small vessel disease, with a particular emphasis on type-1 small vessel disease]

Cerebral small vessel disease (SVD) is defined as difficulty maintaining efficient microcirculation, metabolism, and neural networks caused by degeneration of small vessels of the brain, as well as cognitive or physical dysfunction caused by this difficulty. The most common SVD (i.e., type 1 SVD), which is driven by hypertensive arteriopathy, appears to be more prevalent in people with East Asian ethnicity than in Whites. Recent attention has been paid to a SVD scoring system using major MRI markers of SVD in an attempt to comprehensively semi-quantify the SVD burden in the brain. This concept raised a new question: "Is there a practical threshold for the comprehensive SVD score?" The development of computational methods to assess SVD imaging markers could answer this question, and may help identify the optimal intervention for patients with type 1 SVD to prevent stroke and dementia.

Distribution of cerebral microbleeds in the East and West: Individual participant meta-analysis

OBJECTIVE

We investigated differences in the anatomical distribution of cerebral microbleeds (CMBs) on MRI, hypothesized to indicate the type of underlying cerebral small vessel disease (SVD), between Eastern and Western general populations.

METHODS

We analyzed data from 11 studies identified by a PubMed search between 1996 and April 2014 according to the Preferred Reporting Items for a Systematic Review and Meta-analysis of Individual Participant Data. Study quality measures indicated low or medium risk of bias. We included stroke-free participants from populations aged between 55 and 75 years, categorized by geographic location (Eastern or Western). We categorized CMB distribution (strictly lobar, deep and/or infratentorial [D/I], or mixed [i.e., CMBs located in both lobar and D/I regions]). We tested the hypothesis that Eastern and Western populations have different anatomical distributions of CMBs using multivariable mixed effects logistic regression analyses adjusted for age, sex, and hypertension and clustering by institution.

RESULTS

Among 8,595 stroke-free individuals (mean age [SD] 66.7 [5.6] years; 48% male; 42% from a Western population), 624 (7.3%) had CMBs (strictly lobar in 3.1%; D/I or mixed in 4.2%). In multivariable mixed effects models, Eastern populations had higher odds of D/I or mixed CMBs (adjusted odds ratio 2.78, 95% confidence interval [CI] 1.77-4.35) compared to Western populations. Eastern populations had a higher number of D/I or mixed CMBs (adjusted prevalence ratio 2.83, 95% CI 1.27-6.31).

CONCLUSIONS

Eastern and Western general populations have different anatomical distributions of CMBs, suggesting differences in the spectrum of predominant underlying SVDs, with potential implications for SVD diagnosis and treatment.

Angiotensin-converting enzyme-related cough among Chinese-Americans

BACKGROUND

Few studies have examined the relationship between ethnicity and tolerance of hypertension medications. We investigated the perception that Chinese-Americans may have a higher incidence of chronic cough from angiotensin-converting enzyme inhibitors.

METHODS

We searched electronic databases to identify patients who had received a new lisinopril prescription. This cohort was separated into 295 patients of Chinese descent and 4263 patients in the general population group with an instrument that used surnames to identify Chinese ethnicity. For those who discontinued lisinopril within 1 year, we reviewed medical records to determine reasons for discontinuation. We compared rates of discontinuation overall and due to cough by ethnic group (Chinese vs general population).

RESULTS

The Chinese population was more likely to discontinue their medication (47%) than the general population (31%). When the cause for discontinuation was examined, cough was significantly higher among Chinese, with a relative risk of 2.53; 95% confidence interval (CI), 2.11-3.03. The risk for angioedema was <1%, and no difference in the risk of angioedema was found between the 2 groups. When controlled for age, sex, and smoking, the risk of cough among Chinese-Americans remained significant (relative risk 2.63; 95% CI, 2.20-3.15).

CONCLUSIONS

We observed that our Chinese group was more than twice as likely as the general population to discontinue lisinopril due to cough, controlling for the influence of sex, age, and smoking.

Randomized, controlled, parallel-group comparison of ambulatory and clinic blood pressure responses to amlodipine or enalapril during and after treatment in adult chinese patients with hypertension

BACKGROUND

Few studies have examined the relative efficacy and tolerability of antihypertensive drug classes in Chinese populations.

OBJECTIVE

This study compared the efficacy, tolerability, and duration of antihypertensive effect of amlodipine besylate and enalapril in Chinese patients with hypertension, including elderly patients with isolated systolic hypertension.

METHODS

This randomized, double-blind, double-dummy, parallel-group dose-titration study was conducted at the Department of Medicine and Therapeutics, Chinese University of Hong Kong. Chinese patients aged 18 to 80 years with primary hypertension were enrolled. After a 4-week placebo run-in period, patients were randomly assigned to receive active oral, once-daily treatment with amlodipine (5 mg) or with enalapril (5 mg) for 14 weeks. Treatment doses were titrated at weeks 4 and 8 if necessary according to blood pressure (BP) response and if the dose had been tolerated. Patients also underwent 24-hour ambulatory BP monitoring (ABPM) at the end of the placebo run-in, after the first and last doses of active treatment, and 48 hours after discontinuation of treatment to determine the duration of drug action and to mimic the effect of 2 missed doses.

RESULTS

Eighty patients were recruited for the study (26 men, 54 women; mean [SD] age, 60.5 [11.6] years) (40 patients per group). Thirty-seven patients in each group completed the active treatment phase. Baseline trough BPs were similar: 167.7 (15.0)/94.6 (9.7) mm Hg in the amlodipine group and 168.6 (11.9)/93.4 (9.5) mm Hg in the enalapril group. After 14 weeks of treatment, amlodipine (mean [SD] final dose, 6.3 [2.3] mg) produced greater reductions than enalapril (mean [SD] final dose, 13.3 [6.6] mg) in trough BP (-20.8 [13.2]/-9.2 [9.0] vs -5.5 [14.9]/-3.2 [10.6] mm Hg, respectively; P < or = 0.01). Most of the effect of amlodipine persisted for 72 hours after the last dose (-18.9 [14.6]/-11.1 [11.7] mm Hg), but enalapril had no significant antihypertensive effect at 72 hours (-1.3 [12.3]/-1.8 [9.1] mm Hg). Similar observations were found with ABPM recordings. Cough was reported in 5 patients (12.5%) and 13 patients (32.5%) in the amlodipine and enalapril groups, respectively, but was thought to be treatment related in only 6 patients (15.0%), all in the enalapril group. One of the patients in the enalapril group withdrew from the study because of cough, and 1 patient in the amlodipine group withdrew because of ankle edema.

Body mass index and obesity-related metabolic disorders in Taiwanese and US whites and blacks: implications for definitions of overweight and obesity for Asians

BACKGROUND

Recommendations based on scanty data have been made to lower the body mass index (BMI; in kg/m(2)) cutoff for obesity in Asians.

OBJECTIVE

The goal was to compare relations between BMI and metabolic comorbidity among Asians and US whites and blacks.

METHODS

We compared the prevalence rate, sensitivity, specificity, predictive values, and impact fraction of comorbidities at each BMI level and the BMI-comorbidity relations across ethnic groups by using data from the third National Health and Nutrition Examination Survey and the Nutrition and Health Survey in Taiwan (1993-1996).

RESULTS

For most BMI values, the prevalences of hypertension, diabetes, and hyperuricemia were higher for Taiwanese than for US whites. In addition, increments of BMI corresponded to higher odds ratios in Taiwanese than in US whites for hypertriglyceridemia (P = 0.01) and hypertension (P = 0.075). BMI-comorbidity relations were stronger in Taiwanese than in US blacks for all comorbidities studied. BMIs of 22.5, 26, and 27.5 were the cutoffs with the highest sum of positive and negative predictive value for Taiwanese, US white, and US black men, respectively. The same order was observed for women. For BMIs >27, >85% of Taiwanese, 66% of whites, and 55% of blacks had at least one of the studied comorbidities. However, a cutoff close to the median of the studied population was often found by maximizing sensitivity and specificity. Reducing BMI from >25 to <25 in persons in the United States could eliminate 13% of the obesity comorbidity studied. The corresponding cutoff in Taiwan is slightly <24.

CONCLUSION

These data suggest a possible need to set lower BMI cutoffs for Asians, but where to draw the line is a complex issue.

Manidipine: a review of its use in hypertension

Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40 mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in noncomparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mglday) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or moderate essential hypertension. The BP-lowering effects of the drug in patients with hypertension and type 2 diabetes mellitus or impaired glucose tolerance were not associated with any adverse metabolic effects. The effects of manidipine on UAE in this patient group remain unclear. Manidipine provides an additional treatment option for patients for whom dihydropyridine calcium antagonists are appropriate. Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in non-comparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mg/day) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or mo

Worldwide ethnic distribution of the G protein beta3 subunit 825T allele and its association with obesity in Caucasian, Chinese, and Black African individuals

Recently, it was demonstrated that one allele (825T) of the gene encoding the G protein beta3 subunit (GNB3) is associated with hypertension in Germans. This study investigates a possible association with obesity in young male Germans, Chinese, and black South Africans with low, intermediate, and high 825T allele frequencies, respectively. In each of these three distinct cohorts, the 825T allele frequency was increased significantly in overweight (body mass index [BMI] > or =25 kg/m2) and obese individuals (BMI >27 kg/m2) compared to those with normal weight. The 825T allele frequencies in these three BMI groups were, respectively, 29.5, 39.3, and 47.7% in Germans, 46.8, 53.9, and 58.6% in Chinese, and 83.1, 87.7, and 90.9% in South Africans. In each of these three distinct groups, the 825T allele was significantly associated with obesity with odds ratios between 2 and 3. More urban than rural black Africans were overweight despite similar 825T allele frequencies in both populations, which underscores the role of both genetic and environmental factors. BP values in young male whites increased significantly with increasing BMI values but were independent of the C825T polymorphism, suggesting that hypertension associated with the 825T allele could be a consequence of obesity. Genotyping of 5254 individuals from 55 native population samples from Africa, the Americas, Europe, Asia, Australia, and New Guinea demonstrated highest 825T allele frequencies in black Africans (82%) and intermediate values in east Asians (47%). It is anticipated that high frequencies of the 825T allele in Africans and Asians may contribute to an obesity and hypertension epidemic if Westernization of lifestyles continues.