Tag Archives: stroke

Understanding Sodium Intake and Cardiovascular Risk

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A recent review (ME Cogswell et al. NEJM 2016; 375: 580-5) helps sort out some of the confusion regarding sodium intake and cardiovascular disease. In brief, the authors point out the excessive sodium intake is clearly linked to heart disease, stroke and death.  The importance has been questioned by some due to a few studies suggesting that low sodium intake could also increase the risk of cardiovascular disease.

The authors note that these studies have shown only weak associations & were likely a matter of reverse causation due to the low sodium group having increased numbers of participants with numerous health issues (eg diabetes, hypertension, chronic illness and cardiovascular disease).

By looking at these results based on “Hill’s Criteria” to assess whether an association is causal, the authors show that the association of low sodium intake and cardiovascular disease indicates that this association is NOT causal.

Hill’s criteria:

  • Strength -degree which the exposure is associated with the outcome
  • Consistency -is this finding observed by different persons, in different places/times
  • Specificity -is observation limited to the exposure and the outcome
  • Temporality -did observation cause the outcome or did the outcome affect changes that lead to observation
  • Biologic gradient -?dose-response noted
  • Plausibility -is there a physiologic basis
  • Coherence -does this association conflict with other known facts
  • Experiment -is the finding affected by actions to prevent the exposure
  • Analogy -does an exposure with a similar physiologic action cause the outcome

The authors note that population exposure to sodium correlates better than individual exposure, perhaps due to measurement issues. Key points:

  • “There is strong evidence of a linear, dose-response effect of sodium reduction on blood pressure.  In addition, the evidence shows that sodium reduction prevents cardiovascular disease.”
  • “Reducing the average sodium intake by just 400 mg per day could potentially avert as many as 28,000 deaths and save $7 billion in health care costs annually in the United States.”
  • “Yet sodium levels are high before food reaches the kitchen or table, and the sodium density of the U.S. diet has changed little despite consumer education encouraging individual behavior change.”

My take: If we are to take advantage of the science to reduce cardiovascular deaths, we need to convince manufacturers and restaurants to reduce sodium.

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Highline Trail, Glacier Nat'l park

Highline Trail, Glacier Nat’l park

Crisis or Not -Tough to Change Bad Habits

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For those of you with new resolutions, a sobering study from JAMA shows how difficult it is to change bad habits, even after a heart attack or a stroke.

From Sanjay Gupta’s twitter feed, link and excerpt: Video (1:48) http://ow.ly/sdS7R 

Even a brush with death is often not enough to get us to make better choices. Researchers studied more than 150,000 people from all around the world, rich and poor, urban and rural. Participants answered questions about exercise, diet, and smoking.

Because the group was so large, there were almost 8,000 participants who had survived either a heart attack or a stroke. The health habits of this group were startling. Only 39 percent reported improving their diet, and just 35 percent increased their physical activity. Of those who were smokers, only 52 percent quit. Just 4 percent of those 8,000 people improved their habits in all three areas: smoking, diet, and exercise.

Global Disease Burden

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In 1991, the World Bank and the World Health Organization launched the Global Burden of Disease Study.  A recent article reviews the key findings (NEJM 2013; 369: 448-57).

The goals of the study are to compare the burden of one disease with others; as such, it is “necessary to consider the age at death and life expectancy of persons affected by each disease and to take account of the degree of disability (eg. discomfort, pain, or functional limitations.”  A comprehensive measure of disability, disability-adjusted life-years or DALYs, was used for comparisons.

The study examined 291 types of diseases and injuries as well as 67 risk factors in 187 countries, looking at the years 1990, 2005, and 2010.

Findings:

  • In 2010, there were 2482 million DALYs which is a decrease of 0.6% from 1990.  On the basis of population growth, DALYs would have increased by 37.9% without improvements in disease burden.
  • Major causes of death in 2010: Ischemic heart disease-far ahead #1 (21.1% of deaths, 7850 thousand DALYs), Stroke (6.5% of deaths, 2574 thousand DALYs), Lung/airway cancer (6.1% of deaths, 3033 thousand DALYs), Alzheimer’s (5.9% of deaths, 2022 thousand DALYs), COPD (5.8% of deaths, 3659 thousand DALYs).
  • Global DALYs in 2010 (top ten -starting with #1): Ischemic heart disease, Lower respiratory tract infections, stroke, diarrhea, HIV-AIDs, Malaria, Low Back pain, Preterm birth complications, COPD, and road-traffic injury.
  • Top risk factors (starting with #1): High blood pressure, tobacco smoking (including 2nd-hand smoke), household air pollution, diet low in fruit, alcohol use, high body-mass index, high fasting plasma glucose level, childhood underweight, exposure to outside pollution, physical inactivity, diet high in sodium

Since 1990, there has been a shift.  “In general, communicable, maternal, neonatal, and nutritional conditions decreased in absolute terms.”  The main exceptions were HIV and malaria. Noncommunicable diseases, especially diabetes, have been increasing in terms of percentage and absolute numbers.

Another important change has been a relative increase in disability compared with premature death.  In addition, of the “top 25 causes of years lived with disability, only COPD, diabetes, road-traffic injury, ischemic heart disease, and diarrhea are also among the tope 25 causes of years of life lost.”  “What ails most persons is not necessarily what kills them.”

Bottom-line: While collecting this type of data has many potential limitations, the broad picture it provides should help inform policymakers with priorities for research and intervention.  This data also allows the US to benchmark its efforts compared to other countries.  For example, according to the authors, currently the US has the best global performance with respect to stroke and the worst with respect to lung cancer and Alzheimer’s disease; however, “data and analyses are lacking to elucidate the drivers of these changes in relative performance.”

Neurological Complications Associated with Inflammatory Bowel Disease

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Though I have not seen much in the way of neurological complications in our pediatric inflammatory bowel disease (IBD) population, nevertheless I worry about them.  A recent article provides some insight into the incidence, the pathophysiology and approach to these complications (Inflamm Bowel Dis 2013; 19: 864-72).

Types of neurologic complications: The most common neurologic complication is peripheral neuropathy.  The frequency is quite variable based on data collection method.  In large administrative healthcare data, the prevalence has been reported around 2% whereas in cohort studies the range has been 8-15%. Other complications include meylopathy, cerbrovascular disease, cranial nerve palsy (eg. Melkersson-Rosenthal syndrome), seizures, and demyelinating diseases.

With regard to demyelinating diseases, this has gained additional attention in the setting of biologic agents which have been associated with this complication.  However, the authors note that a pre-biologic treatment study from Olmstead County, observed a prevalence of multiple sclerosis of 1% which was 3.7 times higher than expected.  In addition, similar studies have confirmed this finding.

Potential mechanisms vary greatly depending on the neurologic complication. With regard to cerebrovascular disorders, “venous thromboembolism (VTE) has been shown to occur 3 times more frequently in patients with IBD (the risk increases to 8-10-fold in patients with active colitis) than the general population.”  Hence, VTE prophylaxis is recommended by the authors in hospitalized IBD patients, especially if they are experiencing a disease exacerbation.

In addition to the underlying disease, vitamin deficiencies (eg. Vitamin B12) and medications can trigger neurologic complications.

  • Natalizumab: progress multifocal leukoencephalopathy (PML)
  • Metronidazole: peripheral neuropathy (typically reversible with drug discontinuation)
  • Anti-TNF-α agents (infliximab, adalimumab, certolizumab): demyelination, rarely seizures, and rarely PML
  • Cyclosporine: various neurotoxicity in ~25%

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Heart-healthy Mediterranean Diet

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From AJC (see link below): “The study lasted five years and involved about 7,500 people in Spain. Those who ate Mediterranean-style with lots of olive oil or nuts had a 30 percent lower risk of major cardiovascular problems compared to those who were told to follow a low-fat diet but who in reality, didn’t cut fat very much. Mediterranean meant lots of fruit, fish, chicken, beans, tomato sauce, salads, and wine and little baked goods and pastries.” Methods (at NEJM.org) “In a multicenter trial in Spain, we randomly assigned participants who were at high cardiovascular risk, but with no cardiovascular disease at enrollment, to one of three diets: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat). Participants received quarterly individual and group educational sessions and, depending on group assignment, free provision of extra-virgin olive oil, mixed nuts, or small nonfood gifts. The primary end point was the rate of major cardiovascular events (myocardial infarction, stroke, or death from cardiovascular causes). On the basis of the results of an interim analysis, the trial was stopped after a median follow-up of 4.8 years.”

Related blog entry: Six years later-Mediterranean diet comes out on top | gutsandgrowth

Who needs aspirin?

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Despite a lot of good press for aspirin with regards to prevention of cardiovascular events and cancer prevention, determining who should take aspirin is quite tricky.  This blog entry will discuss the vascular rationale and a subsequent post will tackle the potential of aspirin for colorectal cancer prevention.

At this time, the cardiovascular disease (CVD) rationale includes preventing myocardial infarction [MI] and stroke.  These are the main determinants of risk/benefit for taking aspirin.  In 2009, guidelines from US Preventive Services Task Force (USPSTF) for taking aspirin were published (Ann Intern Med 2009; 150: 396-404).  The following link can be used to access this article:

http://www.uspreventiveservicestaskforce.org/uspstf09/aspirincvd/aspcvdrs.pdf

The recommendations include the following:

Men <45:  Not encourage aspirin for MI prevention

Women <55: Not encourage aspirin for stroke prevention

Men 45-79:  Encourage aspirin when CVD benefit.  Benefit likely if:

  • 45-59 years, 10 -year CVD risk ≥4%
  • 60-69 years, 10-year CVD risk ≥9%
  • 70-79 years, 10-year CVD risk ≥12%
To calculate 10-year CVD risk: http://www.mcw.edu/calculators.htm
Risk factors: age, high blood pressure, diabetes, smoking, history of CVD, total cholesterol level, and HDL cholesterol level

Women 55-79:  Encourage aspirin when stroke benefit.  Benefit likely if:

  • 55-59 years, 10 -year stroke risk ≥3%
  • 60-69 years, 10 -year stroke risk ≥8%
  • 70-59 years, 10 -year stroke risk ≥11%

To calculate 10 -year stroke risk: http://my.clevelandclinic.org/p2/stroke-risk-calculator.aspx

Risk factors: age, high blood pressure, diabetes, smoking, history of CVD, atrial fibrillation, and left ventricular hypertrophy

In addition, it is noted that aspirin is NOT recommended when other NSAIDs are being administered or if history of GI ulcers/risk of serious GI bleeding.

While these recommendations are a useful starting point and the risk calculators are fascinating, the absolute benefit of aspirin remains unclear.  A recent article on this subject indicates that aspirin may not improve mortality (Arch Intern Med. 2012;172(3):209-216. doi:10.1001/archinternmed.2011.628).  This article reviewed nine large randomized placebo-controlled studies, each with at least 1000 participants.  In total, more than 100,000 patients were described in these studies.  While CVD events were reduced by 10%, there was no reduction in mortality for cardiovascular disease (OR 0.99) or for cancer (OR 0.93) among aspirin takers over a mean of 6 years.  Most of the reduction in CVD events were due to a lower rate of non-fatal MI (OR 0.80).  In addition, there was an increase in significant GI bleeding among patients taking aspirin (OR 1.31)

Due to these results, the authors conclude that routine use as primary prevention is not warranted; “treatment decisions need to be considered on a case-by-case basis.”

Additional reference:

  • –Arch Intern Med 2012;172:217-218.  Aspirin Therapy in Primary Prevention: Comment on “Effect of Aspirin on Vascular and Nonvascular Outcomes”