Landmark studies / epidemiology MCQ KFSH board review course

[Mohammed]

The Heart Outcomes Prevention Evaluation (HOPE)

 study found that the ACE inhibitor ramipril can lower the risk of atherosclerotic disease events and death in patients without heart failure but with known atherosclerosis or with diabetes plus at least one cardiovascular risk factor. This benefit was independent of ramipril's effect on blood pressure. Additional benefits were a reduced risk of diabetic nephropathy in diabetic patients, and a lower likelihood of newly diagnosed diabetes. On the other hand, vitamin E in the doses and duration studied (400 IU/day for 4.5 years) did not lower risk significantly.

The Diabetes Control and Complications Trial (DCCT) 

demonstrated that strict glycemic control targeting lower HbA1c goals among patients with T1DM can both delay the onset of retinopathy, nephropathy, and neuropathy and slow the progression of existing microvascular complications. This came at the expense of a threefold higher risk of hypoglycemia, underlying the fact that HbA1c goals should be tailored to the individual.

United Kingdom Prospective Diabetes Study (UKPDS)

showed that long-term complications of type 2 diabetes can be prevented through intensive blood glucose and blood pressure management: The UKPDS included almost 4,000 people with newly diagnosed type 2 diabetes.

ACCORD (Action to Control Cardiovascular Risk in Diabetes) 

Intensively targeting blood sugar to near-normal levels in adults with type 2 diabetes at especially high risk for heart attack and stroke does not significantly reduce the risk of major cardiovascular events, such as fatal or nonfatal heart attacks or stroke, but increases risk of death, compared to standard treatment. 

 Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)

ALLHAT, a randomized, double-blind, multi-center, clinical trial sponsored by the National Heart Lung and Blood Institute, was designed to determine whether the occurrence of CHD is lower for high-risk hypertensive patients treated with a CCB (amlodipine), an ACEI (lisinopril), or an alpha blocker (doxazosin), each compared with diuretic treatment (chlorthalidone). A lipid-lowering subtrial was designed to determine whether lowering cholesterol with an HMG Co-A reductase inhibitor (pravastatin) compared with usual care reduced mortality in a moderately hypercholesterolemic subset of participants. 

Antihypertensive Trial – 42,418 participants

♥ Because of the superiority of thiazide-type diuretics in preventing one or more major forms of CVD and their lower cost, they should be the drugs of choice for first-step antihypertensive therapy.

♥ For the patient who cannot take a diuretic (which should be an unusual circumstance), CCB’s and ACEI’s may be considered.

♥ Most hypertensive patients require more than one drug. Diuretics should generally be part of the antihypertensive regimen. Lifestyle advice should also be provided.

Lipid Trial – 10,355 participants

♥ ALLHAT pravastatin and usual care groups both attained substantial cholesterol reductions, resulting in a relatively modest cholesterol difference between them.

♥ Accordingly, ALLHAT found only a small decrease in CVD event rates (nonsignificant) for pravastatin compared with usual care and no difference in mortality.

♥ The study results do not alter current cholesterol treatment guidelines, which are based on a series of clinical trials with larger cholesterol reductions than that observed in ALLHAT. Thus, cholesterol lowering by lifestyle changes and drug treatment is recommended to reduce CVD morbidity and mortality.

Anglo-Scandinavian Cardiac Outcomes Trial

ASCOT

•Newer antihypertensive drug regimens should be considered 

in preference to older beta-blocker ± diuretic therapies

•Amlodipine-based regimen was beneficial in lowering BP and prevention of CV events compared to beta-blocker ± diuretic-based regimen

•Amlodipine ± perindopril showed reductions in:

–Major CV events 16%

–New-onset diabetes 30%

–Stroke 23%

–Mortality 11%

•Improved BP control* with amlodipine ± perindopril may explain some, but not all, of the benefit

 

MADIT

The MADIT-I study was a proof-of-principle study, and this randomized trial showed that the implantable cardioverter defibrillator (ICD) saves lives in high-risk patients with coronary heart disease. 

The MADIT-II study showed that prophylactic ICD therapy was associated with significantly improved survival in patients with ischemic cardiomyopathy, as defined by documented coronary heart disease and advanced left ventricular dysfunction, without requiring screening for ventricular arrhythmias or inducibility by electrophysiologic testing. 

Epidemiology 

True positive: Sick people correctly diagnosed as sick ,TP

False positive: Healthy people incorrectly identified as sick ,FP

True negative: Healthy people correctly identified as healthy TN

False negative: Sick people incorrectly identified as healthy.FN

Sensitivity

Sensitivity relates to the test's ability to identify positive results.

TP/TP+FN

A test with a high sensitivity has a low type II error rate.

Specificity

Specificity relates to the ability of the test to identify negative results.

TN/TN+FP

A test with a high specificity has a low type I error rate.

Type I error  and Type II error are precise technical terms used in statistics to describe particular flaws in a testing process, 

where a true null hypothesis was incorrectly rejected (Type I error) 

or where one fails to reject a false null hypothesis (Type II error).

positive predictive value, or precision rate is the proportion of positive test results that are true positives  TP/TP+FP
negative predictive value (NPV)  is defined as the proportion of subjects with a negative test result who are correctly diagnosed healthy TN/TN+FN

absolute risk reduction ARR

is the difference between the control group’s event rate (CER) and the experimental group’s event rate (EER). For example: the appearance of lung cancer in a 5 year period. If the probabilities pA and pB of this endpoint under treatments A and B, respectively, are known, then the absolute risk reduction is computed as (pB - pA).

The inverse of the absolute risk reduction, NNT, is an important measure in pharmacoeconomics.  NNT = 1/ARR

‏من جهاز الـ iPad الخاص بي

[Hassan, Imad]

Thanks a lot Mohamed,

very useful information.

 

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From: morning...@googlegroups.com [morning...@googlegroups.com] On Behalf Of Mohammed [msa...@gmail.com]
Sent: Tuesday, July 17, 2012 2:09 PM
To: nooralhedayah; Dr. IbrahimAl-Kadhim; drabd...@yahoo.com; dr_em...@yahoo.com; zaam...@yahoo.com; Ali Al-Janoubi; alsaif_narjis; شقاق; reem....@hotmail.com; TurkeyahAl-Backer; fga11982; garn...@gmail.com; alras...@hotmail.com; abdulrahman rabea; Manar Baqi; mara...@hotmail.com; morning...@googlegroups.com
Cc: morning...@googlegroups.com
Subject: Landmark studies / epidemiology MCQ KFSH board review course

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