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Al is on the way to lead critical ED decisions on CT
Curator and Reporter: Dr. Premalata Pati, Ph.D., Postdoc
Artificial intelligence (AI) has infiltrated many organizational processes, raising concerns that robotic systems will eventually replace many humans in decision-making. The advent of AI as a tool for improving health care provides new prospects to improve patient and clinical team’s performance, reduce costs, and impact public health. Examples include, but are not limited to, automation; information synthesis for patients, “fRamily” (friends and family unpaid caregivers), and health care professionals; and suggestions and visualization of information for collaborative decision making.
In the emergency department (ED), patients with Crohn’s disease (CD) are routinely subjected to Abdomino-Pelvic Computed Tomography (APCT). It is necessary to diagnose clinically actionable findings (CAF) since they may require immediate intervention, which is typically surgical. Repeated APCTs, on the other hand, results in higher ionizing radiation exposure. The majority of APCT performance guidance is clinical and empiric. Emergency surgeons struggle to identify Crohn’s disease patients who actually require a CT scan to determine the source of acute abdominal distress.
Aid seems to be on the way. Researchers employed machine learning to accurately distinguish these sufferers from Crohn’s patients who appear with the same complaint but may safely avoid the recurrent exposure to contrast materials and ionizing radiation that CT would otherwise wreak on them.
Retrospectively, Jacob Ollech and his fellow researcher have analyzed 101 emergency treatments of patients with Crohn’s who underwent abdominopelvic CT.
They were looking for examples where a scan revealed clinically actionable results. These were classified as intestinal blockage, perforation, intra-abdominal abscess, or complex fistula by the researchers.
On CT, 44 (43.5 %) of the 101 cases reviewed had such findings.
Ollech and colleagues utilized a machine-learning technique to design a decision-support tool that required only four basic clinical factors to test an AI approach for making the call.
The approach was successful in categorizing patients into low- and high-risk groupings. The researchers were able to risk-stratify patients based on the likelihood of clinically actionable findings on abdominopelvic CT as a result of their success.
Ollech and co-authors admit that their limited sample size, retrospective strategy, and lack of external validation are shortcomings.
Moreover, several patients fell into an intermediate risk category, implying that a standard workup would have been required to guide CT decision-making in a real-world situation anyhow.
Consequently, they generate the following conclusion:
We believe this study shows that a machine learning-based tool is a sound approach for better-selecting patients with Crohn’s disease admitted to the ED with acute gastrointestinal complaints about abdominopelvic CT: reducing the number of CTs performed while ensuring that patients with high risk for clinically actionable findings undergo abdominopelvic CT appropriately.
Main Source:
Konikoff, Tom, Idan Goren, Marianna Yalon, Shlomit Tamir, Irit Avni-Biron, Henit Yanai, Iris Dotan, and Jacob E. Ollech. “Machine learning for selecting patients with Crohn’s disease for abdominopelvic computed tomography in the emergency department.” Digestive and Liver Disease (2021). https://www.sciencedirect.com/science/article/abs/pii/S1590865821003340
Other Related Articles published in this Open Access Online Scientific Journal include the following:
Every Genome to have its own Personal Antidepressant
Reporter: Aviva Lev-Ari, PhD, RN
A Personal Antidepressant for Every Genome
Monday, December 9, 2013
TAU researchers discover gene that may predict human responses to specific antidepressants
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressants, but they don’t work for everyone. What’s more, patients must often try several different SSRI medications, each with a different set of side effects, before finding one that is effective. It takes three to four weeks to see if a particular antidepressant drug works. Meanwhile, patients and their families continue to suffer.
Now researchers at Tel Aviv Universityhave discovered a gene that may reveal whether people are likely to respond well to SSRI antidepressants, both generally and in specific formulations. The new biomarker, once it is validated in clinical trials, could be used to create a genetic test, allowing doctors to provide personalized treatment for depression.
Doctoral students Keren Oved and Ayelet Morag led the research under the guidance of Dr. David Gurwitz of the Department of Molecular Genetics and Biochemistryat TAU’s Sackler Faculty of Medicine and Dr. Noam Shomron of the Department of Cell and Developmental Biologyat TAU’s Sackler Faculty of Medicine and Sagol School of Neuroscience. Sackler faculty members Prof. Moshe Rehavi of theDepartment of Physiology and Pharmacologyand Dr. Metsada Pasmnik-Chor of the Bioinformatics Unit were coauthors of the study, published in Translational Psychology.
“SSRIs only work for about 60 percent of people with depression,” said Dr. Gurwitz. “A drug from other families of antidepressants could be effective for some of the others. We are working to move the treatment of depression from a trial-and-error approach to a best-fit, personalized regimen.”
Good news for the depressed
More than 20 million Americans each year suffer from disabling depression that requires clinical intervention. SSRIs such as Prozac, Zoloft, and Celexa are the newest and the most popular medications for treatment. They are thought to work by blocking the reabsorption of the neurotransmitter serotonin in the brain, leaving more of it available to help brain cells send and receive chemical signals, thereby boosting mood. It is not currently known why some people respond to SSRIs better than others.
To find genes that may be behind the brain’s responsiveness to SSRIs, the TAU researchers first applied the SSRI Paroxetine — brand name Paxil — to 80 sets of cells, or “cell lines,” from the National Laboratory for the Genetics of Israeli Populations, a biobank of genetic information about Israeli citizens located at TAU’s Sackler Faculty of Medicine and directed by Dr. Gurwitz. The TAU researchers then analyzed and compared the RNA profiles of the most and least responsive cell lines. A gene called CHL1 was produced at lower levels in the most responsive cell lines and at higher levels in the least responsive cell lines. Using a simple genetic test, doctors could one day use CHL1as a biomarker to determine whether or not to prescribe SSRIs.
“We want to end up with a blood test that will allow us to tell a patient which drug is best for him,” said Oved. “We are at the early stages, working on the cellular level. Next comes testing on animals and people.”
Rethinking how antidepressants work
The TAU researchers also wanted to understand why CHL1 levels might predict responsiveness to SSRIs. To this end, they applied Paroxetine to human cell lines for three weeks — the time it takes for a clinical response to SSRIs. They found that Paroxetine caused increased production of the gene ITGB3 — whose protein product is thought to interact with CHL1 to promote the development of new neurons and synapses. The result is the repair of dysfunctional signaling in brain regions controlling mood, which may explain the action of SSRI antidepressants.
This explanation differs from the conventional theory that SSRIs directly relieve depression by inhibiting the reabsorption of the neurotransmitter serotonin in the brain. Dr. Shomron adds that the new explanation resolves the longstanding mystery as to why it takes at least three weeks for SSRIs to ease the symptoms of depression when they begin inhibiting reabsorption after a couple days — the development of neurons and synapses takes weeks, not days.
The TAU researchers are working to confirm their findings on the molecular level and with animal models. Adva Hadar, a master’s student in Dr. Gurwitz’s lab, is using the same approach to find biomarkers for the personalized treatment of Alzheimer’s disease.
For more psychology and psychiatry news from Tel Aviv University, click here.
9. Is it Hypertension or Physical Inactivity: Cardiovascular Risk and Mortality – New results in 3/2013.
Summary By Justin D. Pearlman MD ME PhD MA FACC
1. Physiology of Circulation and Role of Arterial Elasticity
Simplistically, high blood pressure stems from too much volume (salt water) for the vascular space, or conversely, too little space for the volume. Biological signals, such as endothelin, hypoxia, acidosis, nitric oxide, can modify vascular volume by constricting muscles in blood vessel walls. Less simplistically the physics of circulation are governed by numerous factors, with essentials detailed below.
The vascular space has two major circuits: pulmonary (lungs) and systemic (body).
Compliance (C) relates change in volume (ΔV) to change in pressure (ΔP) as a measure of the strength of elasticity, where elasticity summarizes the intrinsic forces that return to original shape after deformation: C = ΔV/ΔP . Those values can be estimated by ultrasound imaging with Doppler blood velocity estimation, by MRI, or invasively. Related properties can also be measured, such as wave propagation time or fractional flow reserve.
The vascular system is dynamic, with frequency components and reactive elements. The fundamental frequency is governed by the heart rate delivering a stroke volume forward into the vasculature; a heart rate of 60/minute corresponds to the frequency of 1 Hertz (1 cycle/second). The pressure rise due to the ejection of stroke volume is called the pulse pressure.
Numerous factors affect blood flow, including blood composition (affected by anemia or blood dilution), leakiness of vessels, elasticity, wave propagation, streamlines, viscosity, osmotic pressure (affected by protein deficiency and other factors),
In a static system, the driving force relates linearly flow by way of resistance (R in units of dyn·s·cm−5): V=IR (Ohm’s law).
Pulmonary:
Systemic:
In a dynamic, reactive system, the relation between the driving potential (pressure gradient), and current (blood flow) is governed by a differential equation. However, use of complex numbers and exponentials recovers simplicity similar to Ohm’s law:
Variables take the form , where t is time, s is a complex parameter, and A is a complex scalar. Complex values simply mean two dimensional, e.g., magnitude (as in resistance) plus phase shift (to account for reactive components).
Complex version of Ohm’s law: where V and I are the complex scalars in the voltage and current respectively and Z is the complex impedance.
Frequency dependent “resistance” is captured by the term impedance.
Breathing in increases the return of blood to the heart, adding to pulse variation.
where PPmax and PPmin are the maximum and minimum pulse pressures determined during a single respiratory cycle
SVV(%) = 100% × [(SVmax − SVmin)/SVmean]
where SVmax and SVmin are the maximum and minimum standard deviation of arterial pressure about the mean arterial pressure during a single respiratory cycle
The nervous system provides both stimulants and inhibitors (sympathetic and vagal nerves) to regulate blood vessel wall muscle tone and also heart rate. Many medications, and anesthetic agents in particular, reduce those responses to stimuli, so the vessels dilate, vascular impedance lowers, pressures drop, and autoregulation is impaired.
Diuretics aim to decrease volume of circulating fluid, vasodilators aim to increase the vascular space, and elasticity treatments will aim to preserve or improve the ability to accommodate changes in volume of fluid.
Vessel dilation near the skin promotes heat loss.
Vascular elasticity is impaired by atherosclerosis, menopause, and endothelial dysfunction (impaired nitric oxide signals response, impaired endothelin response).
Elastance in a cyclic pressure system of systole-diastole (contraction-dilation) presents impedance as a pulsatile load on the heart. Inotropy describes the generation of pressure by cardiac contraction, lusiotropy the compliance of the heart to accept filling with minimal back pressure to the lungs. Chronic exposure to elevated vascular impedance leads to impairment of lusiotropy (diastolic failure, stiff heart) and inotropy (systolic failure, weak heart).
Diuretics enhance renal excretion of sodium. Sodium is the major determinant of circulating volume. Too much blood volume for the amount of vascular space elevates blood pressure. Clinical trials show that use of diuretics to lower blood pressure can prevent strokes, non-inferior to vasodilators and recommended as first line agents.
The most common prescriptions, a mild diuretic, hydrochlorothiazide (HCTZ), is known to improve blood vessel compliance by reducing cell turgor, which explains why its full onset of benefit as well as its slow offset when stopped can take more than one month.
Chlorthalidone – Some evidence suggests that chlorthalidone may be superior to hydrochlorothiazide for the treatment of hypertension. However, a recent study concluded: chlorthalidone in older adults was not associated with fewer adverse cardiovascular events or deaths than hydrochlorothiazide. However, it was associated with a greater incidence of electrolyte abnormalities, particularly hypokalemia.
Alternatively, the pressure can be lowered by increasing the vascular space for a given vascular volume. Examples of mediators for arterial tone (degree of dilation) include nitric oxide, prostacyclin and endothelin.
These work by blocking certain nerve and hormonal signals to the heart and blood vessels, thus lowering blood pressure. Frequently prescribed beta blockers include
metoprolol (Lopressor, Toprol XL)
carvedilol (Coreg)
nadolol (Corgard)
penbutolol (Levatol).
Metabolized nebivololincreases vascular NO production, involves endothelial ß2-adrenergic receptor ligation, with a subsequent rise in endothelial free [Ca2+]i and endothelial NO synthase–dependent NO production
Angiotensin-converting enzyme (ACE) inhibitors
These allow blood vessels to widen by preventing the hormone angiotensin from affecting blood vessels. Frequently prescribed ACE inhibitors include captopril (Capoten), lisinopril (Prinivil, Zestril) and ramipril (Altace).
Angiotensin II receptor blockers
These help blood vessels relax by blocking the action of angiotensin. Frequently prescribed angiotensin II receptor blockers include losartan (Cozaar), olmesartan (Benicar) and valsartan (Diovan).
Another very commonly prescribed drug class of medication counteracts hardening of arteries.
Atheroma lipids have enzyme systems that explicitly disassemble cholesterol esters and reconstruct them inside blood vessel walls,e.g., Anacetrapib, Genetic variants that improve cholesterol levels are stimulating development of additional medications.
We can propose that atheroma build up in arterial blood vessel walls constitutes a maladaptive defense against aneurysm and risk of vessel rupture from hypertension.
Arguably, HMG-CoA reductase inhibitors, statin therapy is a second example of a medication that helps protect vascular elasticity, both by its lipid effects and its anti-inflammatory effects.
The best-selling statin is atorvastatin, marketed as Lipitor (manufactured by Pfizer) and Torvast. By 2003, atorvastatin became the best-selling pharmaceutical in history,[4] with Pfizer reporting sales of US$12.4 billion in 2008.[5] As of 2010, a number of statinsare on the market: atorvastatin (Lipitor and Torvast), fluvastatin (Lescol), lovastatin (Mevacor, Altocor, Altoprev), pitavastatin(Livalo, Pitava), pravastatin (Pravachol, Selektine, Lipostat), rosuvastatin (Crestor) and simvastatin (Zocor, Lipex).[6] Several combination preparations of a statin and another agent, such as ezetimibe/simvastatin, are also available.
Compensatory Effects in the Physiology of Circulation
Before declaring vessel elasticity a new and highly desirable treatment target, consider that it is not firmly established that hardening of arteries (loss of elasticity) is entirely maladaptive.
In parallel with any focus on increasing vascular elasticity or compliance, each of the issues discussed, below merits scrutiny and investigation.
Cardiac Circulation Dynamics
Endothelium morphology, rheological properties of intra vasculature fluid dynamics and blood viscosity provided explanation for shear stress of vessels under arterial pressure
While among other reasons for Hypertension increasing prevalence with aging, arterial stiffening is one.
Yet, stiffer vessels are more efficient at transmitting pressure to distal targets. With aging, muscle mass diminishes markedly and the contribution to circulation from skeletal muscle tissue compressions combined with competent venous valves fades.
Aging and Myocardial Diminished Contractility and Ejection Fraction
With aging heart contractility diminishes. These issues can cause under perfusion of tissues, inadequate nutrient blood delivery (ischemia), lactic acidosis, tissue dysfunction and multi-organ failure. Hardened arteries may compensate. Thus, pharmacotherapy to increase Arterial Elasticity may be counterindicated for patients with mild to progressive CHF.
Diminished contractility will increase the amount of energy needed to maintain circulation. It will change efficiency dramatically – consider the difference between periodically pushing someone sitting on a swing at the resonance frequency if the pendulum versus significantly off resonance.
Increased Arterial Elasticity – Potential Risk to Myocardium
The hypothesis that we should focus on cellular therapies to increase vascular compliance may decrease the circulation efficiency and result in worsening of cardiac right ventricular morphology and development of Dilated cardiomyopathy and hypertrophic cardiomyopathy (muscle thickening and diastolic failure), an undesirable outcome resulting from an attempt to treat the hypertension.
4. Vascular Compliance – The Potential of Noval Therapies
Novel Mechanism for Disease Etiology for the Cardiac Phenotype: Modulation of Nuclear and Cytoskeletal Actin Polymerization.
Lamin A/C and emerin regulate MKL1–SRF activity by modulating actin dynamics
Cornell University, Weill Institute for Cell and Molecular Biology/Department of Biomedical Engineering, Ithaca, New York 14853, USA
Chin Yee Ho &
Jan Lammerding
Brigham and Women’s Hospital/Harvard Medical School, Department of Medicine, Boston 02115, Massachusetts, USA
Chin Yee Ho,
Diana E. Jaalouk &
Jan Lammerding
Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
Maria K. Vartiainen
Present address: American University of Beirut, Department of Biology, Beirut 1107 2020, Lebanon.
Diana E. Jaalouk
Contributions
C.Y.H., D.E.J. and J.L. conceived and designed the overall project, with valuable help from M.K.V. C.Y.H. and D.E.J. performed the experiments. C.Y.H., D.E.J. and J.L. analysed data. C.Y.H. and J.L. wrote the paper.
Laminopathies, caused by mutations in the LMNA gene encoding the nuclear envelope proteins lamins A and C, represent a diverse group of diseases that include Emery–Dreifuss muscular dystrophy (EDMD), dilated cardiomyopathy (DCM), limb-girdle muscular dystrophy, and Hutchison–Gilford progeria syndrome1. Most LMNA mutations affect skeletal and cardiac muscle by mechanisms that remain incompletely understood. Loss of structural function and altered interaction of mutant lamins with (tissue-specific) transcription factors have been proposed to explain the tissue-specific phenotypes1. Here we report in mice that lamin-A/C-deficient (Lmna−/−) and LmnaN195K/N195K mutant cells have impaired nuclear translocation and downstream signalling of the mechanosensitive transcription factor megakaryoblastic leukaemia 1 (MKL1), a myocardin family member that is pivotal in cardiac development and function2. Altered nucleo-cytoplasmic shuttling of MKL1 was caused by altered actin dynamics in Lmna−/− and LmnaN195K/N195K mutant cells. Ectopic expression of the nuclear envelope protein emerin, which is mislocalized in Lmnamutant cells and also linked to EDMD and DCM, restored MKL1 nuclear translocation and rescued actin dynamics in mutant cells. These findings present a novel mechanism that could provide insight into the disease aetiology for the cardiac phenotype in many laminopathies, whereby lamin A/C and emerin regulate gene expression through modulation of nuclear and cytoskeletal actin polymerization.
5. Stabilizing BP Variability is the next Big Target in Hypertension Management
Hypertension caused by Arterial Stiffening is Ineffectively Treated by Diuretics and Vasodilatation Antihypertensives
Barcelona, Spain – An aging population grappling with rising rates of hypertension and other cardiometabolic risk factors should prompt an overhaul of how hypertension is diagnosed and monitored and should spur development of drugs with entirely new mechanisms of action, one expert says. Speaking here at the 2013 International Conference on Prehypertension and Cardiometabolic Syndrome, meeting cochair Dr Reuven Zimlichman (Tel Aviv University, Israel) argued that the definitions of hypertension, as well as the risk-factor tables used to guide treatment, are no longer appropriate for a growing number of patients.
Most antihypertensives today work by producing vasodilation or decreasing blood volume and so are ineffective treatments in ISH patients. In the future, he predicts, “we will have to start looking for a totally different medication that will aim to improve or at least to stabilize arterial elasticity: medication that might affect factors that determine the stiffness of the arteries, like collagen, like fibroblasts. Those are not the aim of any group of antihypertensive medications today.”
Zimlichman believes existing databases could be used to develop algorithms that take this progression of disease into account, in order to better guide hypertension management. He also points out that new ambulatory blood-pressure-monitoring devices also measure arterial elasticity. “Unquestionably, these will improve our ability to diagnose both the status of the arteries and the changes of the arteries with time as a result of our treatment. So if we treat the patient and we see no improvement in arterial elasticity, or the patient is worse, something is wrong, something is not working—either the patient is not taking the medication, or our choice of medication is not appropriate, or the dose is insufficient, etc.”
Oslo, Norway – New research that is only just starting to be digested by the hypertension community indicates that visit-to-visit variability in blood-pressure readings will likely become another way of looking for “at-risk” hypertensive patients and in fact is likely to be more reliable as an indicator of cardiovascular risk than the currently used mean BP.
Discussing the importance of this issue for guidelines and clinical practice, Dr Tony Heagerty (University of Manchester, UK) told the recent EuropeanSocietyofHypertension (ESH) EuropeanMeetingon Hypertension2010: “We are poking around in the dark, offering treatment blankly across a large community, and probably treating a lot of people who don’t need to be treated, while not necessarily treating the highest-risk patients. We should stop being reassured by ‘occasional’ normal BPs. The whole game now is, can we improve the identification of our ‘at-risk’ individuals?”
Heagerty was speaking at a special plenary session on late-breaking research discussing BP variability as a risk factor. This issue has emerged following new analyses reported at the ACC meeting and published in a number of papers in the Lancet and Lancet Neurology earlier this year, which showed that variability in blood pressure is a much stronger determinant of both stroke and coronary disease outcome than average blood pressure.
Three years later, 2/1/2013, Zimlichman also argued that definitions of essential and secondary hypertension have changed very little over the past few decades and have typically only been tweaked up or down related to other CV risk factors. Diastolic hypertension has been the primary goal of treatment, and treatment goals have not adequately taken patient age into account (in whom arterial stiffening plays a larger role), and they have typically relied too heavily on threshold cutoffs, rather than the “linear progression” of risk factors and their impact on organ damage.
(Submitted on 3 May 2013 (v1), last revised 6 May 2013 (this version, v2))
Hypertension is one of the most common age-related chronic diseases and by predisposing individuals for heart failure, stroke and kidney disease, it is a major source of morbidity and mortality. Its etiology remains enigmatic despite intense research efforts over many decades. By use of empirically well-constrained computer models describing the coupled function of the baroreceptor reflex and mechanics of the circulatory system, we demonstrate quantitatively that arterial stiffening seems sufficient to explain age-related emergence of hypertension. Specifically, the empirically observed chronic changes in pulse pressure with age, and the impaired capacity of hypertensive individuals to regulate short-term changes in blood pressure, arise as emergent properties of the integrated system. Results are consistent with available experimental data from chemical and surgical manipulation of the cardio-vascular system. In contrast to widely held opinions, the results suggest that primary hypertension can be attributed to a mechanogenic etiology without challenging current conceptions of renal and sympathetic nervous system function. The results support the view that a major target for treating chronic hypertension in the elderly is the reestablishment of a proper baroreflex response.
Klas H. Pettersen1, Scott M. Bugenhagen2, Javaid Nauman3, Daniel A. Beard2 & Stig W. Omholt3
1Department of Mathematical and Technological Sciences, Norwegian University of Life Science, Norway
2Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
3NTNU Norwegian University of Science and Technology, Department of Circulation and Medical Imaging, Cardiac Exercise Research Group, Trondheim, Norway
Correspondence should be addressed to: KHP (klas.pettersen@gmail.com)
Blood Pressure Single-Nucleotide Polymorphisms and Coronary Artery Sisease (page 995)
Blood pressure (BP) is considered a major cardiovascular risk factor that is influenced by multiple genetic and environmental factors. However, the precise genetic underpinning influencing interindividual BP variation is not well characterized; and it is unclear whether BP-associated genetic variants also predispose to clinically apparent cardiovascular disease. Such an association of BP-related variants with cardiovascular disease would strengthen the concept of BP as a causal risk factor for cardiovascular disease. In this issue of Hypertension, analyses within the Coronary ARtery DIsease Genome-Wide Replication And Meta-Analysis consortium indicate that common genetic variants associated with BP in the population, indeed, contribute to the susceptibility for coronary artery disease (CAD). Lieb et al tested 30 single-nucleotide polymorphisms—that based on prior studies were known to affect BP—for their association with CAD. In total, data from 22 233 CAD cases and 64 762 controls were analyzed. The vast majority (88%) of BP-related single-nucleotide polymorphisms were also shown to increase the risk of CAD (as defined by an odds ratio for CAD >1; Figure). On average, each of the multiple BP-raising alleles was associated with a 3% (95% confidence interval, 1.8%–4.3%) risk increase for CAD.
Masked Hypertension in Diabetes Mellitus (page 964)
The first important finding in the IDACO study of masked hypertension (MH) in the population with diabetes mellitus and non–diabetes mellitus was that antihypertensive treatment converted some sustained hypertensives into sustained normotensives; this resulted in an increased cardiovascular disease risk in the treated versus untreated normotensive comparator group (Figure). Not surprisingly, normalization of blood pressure (BP) with treatment did not eliminate the lifetime cardiovascular disease burden associated with prior elevated BP nor did it correct other cardiometabolic risk factors that clustered with the hypertensive state.
The second important IDACO finding was that treatment increased the prevalence of MH by decreasing conventional BP versus daytime ambulatory BP (ABP) by a ratio of ≈3 to 2. The clinical implication of increased prevalence of MH with therapy in the population of both diabetes mellitus and non–diabetes mellitus was that these subjects did not receive sufficient antihypertensive therapy to convert MH into normalized ABP (ie, treated, normalized ABP being the gold standard for minimizing cardiovascular disease risk). Indeed, there is a transformation-continuum from sustained hypertension to MH and finally to sustained normotension with increasing antihypertensive therapy. These IDACO findings strongly suggest that many physicians mistakenly have their primary focus on normalizing in-office rather than out-of-office home BP and/or 24-hour ABP values and this results in an increased prevalence of MH. However, what constitutes optimal normalized ABP will remain empirical until established in randomized controlled trials.
Elevated blood pressure (BP) is a strong, independent, and modifiable risk factor for stroke and heart disease. BP is a heritable trait, and genome-wide association studies have identified several genetic loci that are associated with systolic BP, diastolic BP, or both. Although the variants have modest effects on BP, typically 0.5 to 1.0 mm Hg, their presence may act over the entire life course and, therefore, lead to substantial increase in risk of cardiovascular disease (CVD). However, the independent impact of these variants on CVD risk has not been established in a prospective setting. Havulinna et al genotyped 32 common single-nucleotide polymorphisms in several Finnish cohorts, with up to 32 669 individuals after exclusion of prevalent CVD cases. The median follow-up was 9.8 years, during which 2295 incident CVD events occurred. Genetic risk scores were created for systolic BP and diastolic BP by multiplying the risk allele count of each single-nucleotide polymorphism by the effect size estimated in published genome-wide association studies on BP traits. The GRSs were strongly associated with baseline systolic BP, diastolic BP, and hypertension (all P<10–62). Hazard ratios for incident CVD increased roughly linearly by quintile of systolic BP or diastolic BP GRS (Figure). GRSs remained significant predictors of CVD risk after adjustment for traditional risk factors, even including BP and use of antihypertensive medication. These findings are consistent with a lifelong effect of these variants on BP and CVD risk.
1Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia
2Biostatistics Unit, Group Health Research Institute, Seattle, Washington, USA
3Obesity and Population Health Unit, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
Correspondence toDr Susan M Shortreed, Biostatistics Unit, Group Health Research Institute, 1730 Minor Avenue, Suite 1600, Seattle, WA 98101, USA; shortreed.s@ghc.org
Published Online First 8 March 2013
Abstract
Objective In the majority of studies, the effect of physical activity (PA) on cardiovascular disease (CVD) and mortality is estimated at a single time point. The impact of long-term PA is likely to differ. Our study objective was to estimate the effect of long-term adult-life PA compared with long-term inactivity on the risk of incident CVD, all-cause mortality and CVD-attributable mortality.
Design Observational cohort study.
Setting Framingham, MA, USA.
Patients 4729 Framingham Heart Study participants who were alive and CVD-free in 1956.
Exposures PA was measured at three visits over 30 years along with a variety of risk factors for CVD. Cumulative PA was defined as long-term active versus long-term inactive.
Main outcome measures Incident CVD, all-cause mortality and CVD-attributable mortality.
Results During 40 years of follow-up there were 2594 cases of incident CVD, 1313 CVD-attributable deaths and 3521 deaths. Compared with long-term physical inactivity, the rate ratio of long-term PA was 0.95 (95% CI 0.84 to 1.07) for CVD, 0.81 (0.71 to 0.93) for all-cause mortality and 0.83 (0.72 to 0.97) for CVD-attributable mortality. Assessment of effect modification by sex suggests greater protective effect of long-term PA on CVD incidence (p value for interaction=0.004) in men (0.79 (0.66 to 0.93)) than in women (1.15 (0.97 to 1.37)).
Conclusions
Cumulative long-term PA has a protective effect on incidence of all-cause and CVD-attributable mortality compared with long-term physical inactivity.
In men, but not women, long-term PA also appears to have a protective effect on incidence of CVD.
Summary – PENDING
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