The associations of diastolic blood pressure with the risk of stroke in Western and Eastern populations

Are fixed-dose combination antihypertensives suitable as first-line therapy?

OBJECTIVE

To contemplate how initial antihypertensive therapy with fixed-dose combinations (FDC) might be incorporated into clinical practice, based on a compilation of evidence comparing FDCs with monotherapy and loose-dose combinations in varying patient populations.

METHODS

A non-systematic search of PubMed (from 2007 to 2012) was performed for randomized, controlled trials in order to capture the evidence on FDC versus monotherapy and loose-dose combinations as first-line therapy. The literature search focused on calcium channel blocker (CCB)-renin angiotensin system (RAS) blocker combinations. Additionally, any relevant papers known to the authors were included. International recommendations from published hypertension treatment guidelines were also consulted.

RESULTS

The results of this literature review identified two emergent issues. Firstly, there is a discord between antihypertensive use and actual blood pressure (BP) control achieved - despite an increase in the use of antihypertensives over the last 10 years, BP control rates remain low. Secondly, a greater association between BP and cardiovascular risk in Asians may magnify this discrepancy. A number of international guidelines are recommending early combination therapy, such as CCB-RAS blocker combinations in the majority of patients based on the available evidence, with such combinations showing benefits in terms of compliance, BP lowering and control, and safety. Additionally, recent studies have indicated that improved BP control may be achieved with simplified guidelines and the use of FDCs. Overall, these findings indicate that FDC could be used as first-line.

CONCLUSIONS

The findings from this literature review suggest that physicians may need to readdress their approach to antihypertensive treatment. Earlier use of antihypertensive FDC (including first-line) may help to shrink the current gap between antihypertensive use and BP target control achieved. Most guidelines acknowledge that combination therapy is required in the majority of patients, and FDC are regarded as a suitable alternative, having demonstrated better compliance compared with loose-dose combinations.

Results of the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial by geographical region

OBJECTIVE

To examine regional differences in the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial.

DESIGN

Double-blind, randomized, international clinical trial.

SETTING

Six hundred and sixty-one clinical centers in 15 countries.

PATIENTS

Hypertensive volunteers (n = 16,602) with > or =1 additional cardiovascular risk factor, grouped into four regions: USA (n = 8144), Canada (n = 3405), Western Europe (Spain, UK, Italy, Sweden, Germany; n = 2048) or 'other' (Bulgaria, Israel, Mexico, Czech Republic, Hungary, Poland, Slovakia, Brazil; n = 2879); subgroupings included country and state/province within the USA and Canada.

INTERVENTIONS

Randomized to COER-verapamil or the investigator's choice of either atenolol or hydrochlorothiazide, titrated and additional drugs added as required.

MAIN OUTCOME MEASURES

Baseline characteristics; blood pressure control, medication adherence and lost-to-follow-up at 2 years; and composite primary endpoint (stroke, myocardial infarction, cardiovascular death) by regional groupings.

RESULTS

Regional differences were found at baseline for age, gender, blood pressure, percentage receiving antihypertensive drug therapy, initial choice of atenolol or hydrochlorothiazide, and risk factor profile. Blood pressure control rates increased markedly during follow-up in all regions, but varied significantly by region. Blood pressure control, medication adherence and lost-to-follow-up rates were poorest in the USA. After adjustment for baseline differences, the primary-event rate for each region was significantly lower than for the USA. Although baseline factors, blood pressure control and event rates varied by region, treatment differences did not.

CONCLUSION

Despite differences in baseline and follow-up measures across geographical regions, the absence of treatment differences by region suggests that the overall findings of CONVINCE are robust.

Tooth loss is associated with an increased risk of hypertension in postmenopausal women

Tooth loss has been associated with an increased risk of vascular diseases such as coronary heart disease and cerebrovascular disease. Little is known whether hypertension is an important factor linking 2 phenomena in postmenopausal women. We compared an incidence of hypertension and traditional risk factors for vascular diseases between 2 age-matched groups: 67 postmenopausal women with missing teeth and 31 without missing teeth. In addition to blood pressure, serum concentration of total cholesterol, high- and low-density lipoprotein cholesterol and triglycerides, plasma angiotensin-converting enzyme activity, plasma angiotensin II concentration, plasma renin activity, and resting heart rate were measured as traditional risk factors for vascular diseases. Subjects without missing teeth had significantly lower diastolic blood pressure than did subjects with missing teeth (P=0.021). The former tended to have lower systolic blood pressure than did the latter (P=0.058). There were no significant differences in other variables between subjects with and without missing teeth. The odds ratio of having hypertension in subjects with missing teeth was 3.59 (95% confidence interval, 1.10 to 11.7) after adjustment of obesity, hypercholesterolemia, and hypertriglyceridemia. Our results suggest that hypertension may be an important factor linking tooth loss and an increased risk of vascular diseases in postmenopausal women.

Blood pressure and cardiovascular disease in the Asia Pacific region

OBJECTIVES

To estimate age-, sex- and region-specific associations of blood pressure with cardiovascular diseases.

DESIGN

Relative risk estimates and 95% confidence intervals were calculated from Cox models, stratified by sex and cohort, and adjusted for age at risk on individual participant data from 37 cohort studies. Repeat measurements of blood pressure were used to adjust for regression dilution bias.

SETTING

Studies included in the Asia Pacific Cohort Studies Collaboration from Australia, mainland China, Hong Kong, Japan, New Zealand, Singapore, South Korea, and Taiwan.

PARTICIPANTS

A total of 425 325 study participants.

MAIN OUTCOMES MEASURES

Stroke, ischaemic heart disease, total cardiovascular death.

RESULTS

During over 3 million person-years of follow-up, 5178 strokes, 3047 ischaemic heart disease events and 6899 cardiovascular deaths were observed. Continuous log-linear associations were seen between systolic blood pressure and the risks of all three endpoints down to at least 115 mmHg. In the age groups < 60, 60-69, and > or = 70 years, a 10 mmHg lower usual systolic blood pressure was associated with 54% (95% CI 53-56%), 36% (34-38%) and 25% (22-28%) lower stroke risk, and 46% (43-49%), 24% (21-28%) and 16% (13-20%) lower ischaemic heart disease risk, respectively. All associations were similar in men and women. Blood pressure was at least as strongly associated with cardiovascular events in Asian populations compared to Australasian populations.

CONCLUSIONS

About half of the world's cardiovascular burden is predicted to occur in the Asia Pacific region. Blood pressure is an important determinant of this burden, with considerable potential benefit of blood pressure lowering down to levels of at least 115 mmHg systolic blood pressure.

The emergence of coronary heart disease in populations of Chinese descent

Most countries in oriental Asia have not yet experienced the 'western' coronary heart disease (CHD) epidemic despite substantial economic development. An exception has been Singapore. We compared mortality and CHD risk factors in Singapore with two Oriental locations, Hong Kong and mainland China, which have not experienced the CHD epidemic. Mortality data from World Health Statistics Annuals age standardised for each location and were supplemented by local data. Risk factor data was obtained from population-based surveys using similar protocols in each location. Measures included diet, blood lipids, blood pressure, height and weight. CHD mortality in the year chosen for comparison, 1994, was significantly higher for Singapore Chinese males [108 (95.2-119.1)] than Chinese males in Hong Kong [44.3 (40.2-48.2)] or China [45.5 (44.2-46.8)]. Female CHD mortality was also relatively higher in Singapore Chinese. The only CHD risk factor markedly higher in Singapore Chinese was serum cholesterol; Singapore males [5.65 (5.55-5.75)], females [5.60 (5.50-5.70)], Hong Kong males [5.21 (5.11-5.31)], females [5.20 (5.10-5.29)] and China males [4.54 (4.46-4.62)], females [4.49 (4.42-4.55)]. Dietary differences in saturated fat consumption were consistent with this. Although there was little difference in total fat intake, a higher consumption of dietary saturated fat and lower consumption of polyunsaturated fat, accompanied by higher serum cholesterol, appear to explain the relatively high CHD mortality in Singapore compared with Hong Kong and mainland China. Differences in body mass index, blood pressure and smoking between locations did not explain the differences in CHD mortality.

Hypertension in patients presenting with stroke

Hypertension is a major risk factor for stroke disease. There is now some international agreement on what constitutes hypertension, and at what level of blood pressure treatment is required. Large randomised controlled trials demonstrate the benefit of reducing blood pressure for the primary and secondary prevention of stroke disease. Studies have also demonstrated the benefit of particular classes of antihypertensive agents in certain patient groups. Research is beginning to elucidate the problems of hypertension in the acute phase of ischaemic stroke and the therapeutic strategies that may be helpful. Given the significant impact of stroke disease on all health services, it remains an important priority to determine the best management of hypertension in stroke.