After adjusted for the effect of baseline MCE risk and reduction in SBP, the multivariate meta-regression showed baseline SBP was not significantly related to the RD for all the relevant outcomes examined (p>0.22) except MCE (p=0.0226). However, the baseline MCE risk remained significantly related to the RD for all the outcomes (p<0.01) except CHD (p=0.1011). The reduction in SBP remained significantly related to the RD for deaths due to CVD, MCE, CHF and stroke (p<0.01) but not to the RD for all-cause death (p=0.3788) and CHD (p=0.8755). / Conclusions. This study showed that baseline CVD risk and reduction in blood pressure were strongly and consistently related to the absolute effect of treatment and surprisingly the baseline blood pressure was not. The findings lend direct support to the overall risk approach to primary prevention and suggest that contrary to conventional wisdom and current practice, the overall CVD risk rather than blood pressure alone should be used to identify and treat people to prevent major CVD events through anti-hypertensive drugs. These findings suggest that anti-hypertensive drugs should be given to those who have a high future CVD risk rather than high blood pressure alone so as to achieve better cost-effectiveness of anti-hypertensive drugs for primary prevention. / Data extraction and analyses: Two reviewers independently abstracted data on baseline variables, variables that determine methodological quality, and outcomes. The following main outcomes were assessed: all-cause deaths, deaths due to cardiovascular disease, death due to causes other than CVD, major cardiovascular events (MCE), congestive heart failure (CHF), stroke, and coronary heart disease (CHD). / Key words. hypertension, antihypertensive drugs, cardiovascular disease, meta-analysis, systematic review, randomized controlled trial, primary prevention, baseline risk, evidence based medicine / Meta-analysis was used to obtain the overall odds ratio (OR) and risk difference (RD). Forest plots, bubble plots and funnel plots were used to show the results visually or to check biases. Meta-regression was used to identify factors that may independently determine the effect of antihypertensive drugs. The control CVD risk, initial mean blood pressure and reduction in blood pressure were examined. / Method. Identification of studies: The databases searched included ACP Journal Club, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Cumulative Index to Nursing & Allied Health Literature, Chinese Medical Current Contents to identify relevant studies between 1966 and 2005. We also examined references from relevant trials, reviews and meta-analyses. For trials to be included in this review, they have to have the following characteristics: (1) essential hypertension in patients of any age, sex and race; (2) treatment intervention is antihypertensive drugs; (3) control intervention is a placebo or no treatment; (4) endpoint outcomes are all-cause death and major cardiovascular events; and (5) randomized controlled trials. / Objective. Although the overall risk approach to cardiovascular disease (CVD) primary prevention has been widely adopted, direct evidence that supports this policy is however weak and in some aspects lacking. Importantly, there is no direct evidence to show, between blood pressure and CVD risk, which is a better predictor of the absolute benefit from anti-hypertensive drugs. The evidence that the absolute benefit increases as the future CVD risk increases does not necessarily mean that treating high risk people will be more cost-effective than treating hypertensive people as blood pressure may also be positively related to treatment benefit. The high risk approach would be preferable only when we can show with strong evidence that blood pressure is not related to the absolute benefit of treatment or the CVD risk is much more strongly related to the benefit than blood pressure. We thus conducted this systematic review to examine the evidence from randomized controlled trials to directly show how blood pressure and CVD risk are related to the absolute benefit from anti-hypertensive drugs and compare the capability of the two factors in predicting the benefit. The stronger predictor should be a better indicator for identifying those who should be treated with anti-hypertensive drugs. / Results. Twenty-two eligible randomized controlled trials with a total of 55,448 participants were identified from 1967 to 2004. The average follow-up was 45.6 months ranging from 13 to 84 months. The combined RD and OR for all-cause deaths, deaths due to CVD, MCE, CHF, Stroke and CHD were all statistically significant, showing a consistent and considerable reduction in the risk of these outcomes due to the treatment of anti-hypertensive drugs (p<0.01). / Jiang, Yu. / "September 2007." / Adviser: Jin Ling Tang. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4657. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 107-115). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344098 |
| Date | January 2007 |
| Contributors | Jiang, Yu, Chinese University of Hong Kong Graduate School. Division of Public Health. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (x, iv, 130 p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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