Category Archives: cardiology

Diminishing returns in medical therapy

I’m a few months late, but I want to mention an editorial by Rodney Hayward that was published in The BMJ in December 2015. His topic is treatment of diabetes, but the principles he discusses also apply to other areas of medicine. The key concept is that even in high risk conditions such as diabetes, adding a second or third medication brings diminishing absolute returns as residual risk decreases as each additional treatment is added. He starts by describing the disturbing consequences of untreated or poorly managed diabetes, and how things have changed with modern therapies.

When I began my medical training in 1980, I commonly encountered patients whose bodies were ravaged by end stage complications of diabetes. These patients often had marked visual impairment, debilitating neuropathy, myopathies, and diabetes related renal insufficiency, well before age 65 years. I still occasionally see such individuals, but they are rare, and tend to come from the 10-15% of patients who still have poor glycemic control. Improvement in diabetes care is a medical success story, but increasing evidence suggests that overly aggressive treatment is an under-appreciated problem.

The problem is that focusing on relative treatment effects ignores the law of diminishing returns; past a certain point, additional reductions in HbA1c have limited benefit in absolute terms for most older patients with type 2 diabetes. Hayward explains:

Diminishing returns is a mathematical fact, not a theory. Try this simple experiment. Serially tear a piece of paper in half and throw one half away. You will notice that the relative effects never diminish (you reduce the piece of paper by half each time), but it doesn’t take long for the 50% you throw away to become tiny. The many patients with end stage diabetes we saw in the 1980s often spent years with poor control of both glycemia and blood pressure. They had no access to metformin, home blood glucose monitoring, angiotensin converting enzyme inhibitors, calcium channel blockers, and a host of other modern interventions. Each of these interventions substantially reduces disease progression and has an even larger effect on end stage diabetes complications. Because each intervention substantially reduces end stage complications, it should not be surprising that recent evidence has found intensive glycemic control to have a small absolute effect on end stage complications for most patients with type 2 diabetes. The law of diminishing returns predicts this result. Also, as the benefits of tighter glycemic control become smaller, the chances that treatment harms will outweigh treatment benefits become much greater.

Hayward ends by stating that the public good would best be served by focusing on the minority of diabetes patients who continue to be at substantial risk of diabetes-related morbidity and mortality and promoting more shared decision making with older diabetes patients who already have at least moderate blood glucose control.

The same principle of diminishing returns applies in other areas of medicine, such as in medications that reduce cardiovascular risk by lowering blood pressure or cholesterol. As the second and third medication is added, the patient’s risk of experiencing a cardiovascular event diminishes and in some cases a point can be reached where the absolute benefits become very small and it becomes difficult to tell whether benefits outweigh harms. When benefits become small, it can sometimes be hard to determine whether they exist at all or, perhaps, exist in only in patients with certain characteristics. See this post by Harlan Krumholz for a discussion of these issues in the area of treatment of high blood pressure.

In the area of cholesterol-lowering drugs, the new PCSK9 inhibitors have been in the news and I’ve previously discussed them on this blog (here, here and here). Two of these drugs, evolocumab and alirocumab, are approved in the U.S. and so far aren’t selling well. There are several reasons for that, including that the outcomes trials haven’t been completed yet and that the drugs are much more expensive than statins, almost all of which are available as generics. Another reason, related to the first two, is that insurance companies have imposed strict preauthorization requirements for these drugs. Another reason relates to the theme of this post, namely the diminishing returns from adding additional drugs. I’m going to take the treatment of heterozygous familial hypercholesterolemia (HeFH) as an example, specifically patients with HeFH who do not have clinical atherosclerotic cardiovascular disease and who are thus being treated to prevent a first event (i.e., “primary prevention”).

HeFH greatly increases the risk of developing premature atherosclerotic cardiovascular disease compared to individuals with normal levels of cholesterol. Before statins became available, the drugs that were available were not very effective. However, in recent decades, first moderate intensity and then high intensity statins were instituted as standard treatment of HeFH, often with additional drugs such as ezetimibe. According to UpToDate, atorvastatin can reduce LDL by up to 54% and rosuvastatin can reduce LDL by up to 63%. Ezetimibe can lower LDL by another 15% or so in patients on a statin. Given that most patients with HeFH have LDL in the 200s or below, a reduction of 50-60% achieves very reasonable LDL levels. There is evidence that even moderate doses of statins greatly reduce the risk of heart disease in HeFH patients who are being treated for primary prevention. A study published in JAMA in 2014 showed that young adults with HeFH have near-normal levels of atherosclerosis 10 years after initiation of statin therapy. The use of high intensity statins has been shown to greatly reduce the progression of atherosclerosis in adult HeFH patients (see here and here) even when compared to moderate statin therapy. Thus, HeFH patients who start treatment early and are able to reduce their LDL to normal or near-normal levels over many years with a statin or statin + ezetimibe often do not need an additional drug, as their risk is greatly reduced.

So which HeFH patients do need an additional LDL-lowering therapy, such as a PCSK9 inhibitor? To my knowledge, there are no risk calculators available to guide decisions in this area. HeFH patients who start with very high LDL, who can’t tolerate high doses of statins or can’t tolerate statins at all, who started treatment late, who have additional cardiovascular risk factors, or who have had imaging that shows significant subclinical atherosclerosis, are going to be at higher risk, on average. There is quite a bit of uncertainty involved, as with estimation of cardiovascular risk in general. In addition, there are personal preferences involved, as people vary greatly in terms of how much risk they are willing to live with.

Interestingly, a task force of the International Atherosclerosis Society just published a consensus statement in The Lancet Diabetes & Endocrinology that discusses some of the factors involved in determining cardiovascular risk in FH. Although the criteria they propose for use of additional therapies are more stringent than I foresee being adopted in the U.S., the paper contains some very useful discussion of the heterogeneity of cardiovascular risk in FH and ways of trying to predict who is at higher risk. I’m pasting in their proposed criteria below, in case anyone is interested, but I do recommend the entire paper.

proposed criteria for severe FH

More data on alirocumab and diabetes risk

I happened to see an abstract from the American Heart Association Scientific Sessions in which the authors slice and dice the alirocumab data to see if they could find effects on development of diabetes or impaired glucose control in patients without diabetes at baseline. As you can see in the table below, there are some numerical differences in (1) patients with normal blood sugar at baseline who developed impaired glucose control and (2) patients with impaired glucose control who developed diabetes. The differences were not statistically significant. No resolution of this issue is likely until the results of the outcomes trials are available. See my previous post on this here.

alirocumab abstract

2013 Gina Kolata article on PKSK9 inhibitors was inaccurate

2013 front page New York Times article by Gina Kolata on PCSK9 inhibitors was inaccurate. Here is Kolata’ lede:

She was a 32-year-old aerobics instructor from a Dallas suburb — healthy, college educated, with two young children. Nothing out of the ordinary, except one thing.    

Her cholesterol was astoundingly low. Her low-density lipoprotein, or LDL, the form that promotes heart disease, was 14, a level unheard-of in healthy adults, whose normal level is over 100.

The reason was a rare gene mutation she had inherited from both her mother and her father. Only one other person, a young, healthy Zimbabwean woman whose LDL cholesterol was 15, has ever been found with the same double dose of the mutation.           

Here is an excerpt from the FDA clinical review of Sanofi/Regeneron’s PCSK9 inhibitor alirocumab:

We are aware of three cases of individuals homozygous (or compound heterozygous) for loss-of-function PCSK9 alleles with very low LDL-C concentrations that have been reported in the literature:

1.  a 21-year-old African woman with an LDL-C of 15 mg/dL; no further information about this patient was provided, except that she was identified for genotyping at a postnatal clinic,

2.  a 32-year-old African American woman with an LDL-C of 14 mg/dL; she is an apparently healthy, normotensive, fertile, college-educated individual with normal liver and renal function tests, and

3.  a 49-year-old French white man who was found to have extremely low LDL-C (7 mg/dL) on admission for rapid-onset of an insulin-requiring diabetes mellitus of unknown etiology; LDL-C not during acute illness was reported to be 16 mg/dL. This patient was shown to have moderate liver steatosis on abdominal ultrasound with normal hepatic enzymes and liver function tests. He had no reported history of diarrhea, eye, or neurological abnormalities related to any vitamin deficiency. His mother was deceased at age 66 from dementia, whereas his father was healthy at age 79. His grandparents died at the ages of 79, 87, 91, and 94 years.

At this time there are too few cases to provide conclusive data about loss-of-function PCSK9 polymorphisms and the risk of human disease, although given the association of statins with diabetes risk, the development of diabetes in the 49-year-old man discussed above is of interest. (See Dr. Roberts’ safety review for further discussion of alirocumab and glycemic parameters).

The third case is the one missed by Kolata. It was published in Arteriosclerosis, Thrombosis, and Vascular Biology, an American Heart Association journal, in 2009, and could have been found with a PubMed search. The case is interesting in that it conflicts with one of the oft-repeated but inaccurate narratives with respect to PCSK9 inhibitors, the idea that all known persons with extremely low LDL due to having two PCSK9 loss-of-function mutations are completely healthy. I agree with the FDA reviewer that there are too few such cases to provide conclusive data about loss-of-function PCSK9 polymorphisms that result in extremely low LDL levels and the risk of disease. (The issue of whether alirocumab increases blood glucose and the risk of developing diabetes is also discussed extensively in the review, with the reviewer concluding that the evidence is inconclusive at this point.)

Do PCSK9 inhibitors affect diabetes risk?

Two PCSK9 inhibitors, evolocumab and alirocumab, are under consideration at the FDA and will be the subject of advisory committee meetings on June 9 and 10. Evolocumab and alirocumab are monoclonal antibodies that inhibit proprotein convertase subtilisin/kexin type 9 (PCSK9), an enzyme that plays a role in regulating levels of LDL cholesterol by binding to LDL receptors and promoting their degradation; the resulting reduction in LDL receptors reduces the liver’s ability to remove circulating LDL. PCSK9 inhibitors prevent PCSK9 from degrading LDL receptors; the increased LDL receptor density results in increased clearance of LDL from the bloodstream. The expectation is that lower LDL levels in patients who receive PCSK9 inhibitors will result in a reduction in cardiovascular events and this strategy is currently being tested in large outcomes trials, which will be completed in a few years. Until those trials are completed, the safety and efficacy of these drugs will not be known.

One of the unknowns with PCSK9 inhibitors is their effect (if any) on blood glucose levels and the development of new-onset diabetes. Statins are known to increase the risk of new-onset diabetes by about 9% overall, with increased risk from intensive vs. moderate intensity statin therapy. One reason to wonder whether PCSK9 inhibitors might have a similar effect is that both statins and PCSK9 inhibitors, though having different mechanisms of action, both involve the removal of LDL through upregulation of LDL receptors. The reason statins increase blood glucose is unknown, but recently it has been suggested that that the LDL receptor might be involved, with greater LDL receptor activity correlating with a higher risk of diabetes. A recent study showed that patients with familial hypercholesterolemia (FH) in the Dutch FH registry have a lower prevalence of type 2 diabetes as compared to their unaffected relatives. FH is a genetic disease in which the LDL receptor function is reduced, leading to higher serum levels of LDL cholesterol. In addition, the study found a dose-response relationship, with more severe FH mutations linked to lower risk of diabetes as compared to less severe mutations. In other words, the study showed an association between less functional LDL receptors and a lower prevalence of type 2 diabetes. In an editorial, David Preiss and Naveed Sattar note that the study suggests that “the expression and function of LDL receptors may be important for glucose homeostasis” and that the advent of PCSK9 inhibitors provides an opportunity to further examine a possible link between LDL receptor expression and glycemia and diabetes risk.

I’ve looked at some of the published data on PCSK9 inhibitors and blood glucose and diabetes risk. With respect to alirocumab, I abstracted a subset of the data in an abstract presented at the March 2015 American College of Cardiology conference.

As you can see, the data show small numerical increases in new-onset diabetes and worsening of preexisting diabetes, as well as larger increases in fasting glucose and hemoglobin A1c over the course of a year in patients on alirocumab as compared to patients on placebo (all patients were also on a statin). With respect to evolocumab, I found the following data:

1. A 52-week placebo-controlled trial of evolocumab in patients with hyperlipidemia published in the New England Journal of Medicine in 2014 found the mean change from baseline for fasting glucose at week 52 was 1.3 mg per deciliter for evolocumab and 0.4 mg per deciliter for placebo. The mean change from baseline for HbA1c at week 52 was 0.02% for evolocumab and 0.00% for placebo (table 3 and supplementary table S3).

1. The Osler trials recently published in the New England Journal of Medicine showed that 1.1% of the patients who received evolocumab developed diabetes, as compared to 0.7% of the patients in the standard of care group.

What do all these small differences add up to? It’s not possible to say yet, but I assume someone will do a meta-analysis at some point, and there may be some discussion of this issue in the FDA review of these agents, which will be posted prior to advisory committee meetings.

I should note that even if PCSK9 inhibitors do increase blood glucose and the risk of developing diabetes, they would still be very worthwhile for patients who are at significant risk of heart attack and stroke, if they are shown to be effective and have acceptable safety.

Thoughts on the recent PCSK9 inhibitor studies

Two studies on the PCSK9 inhibitors evolocumab and alirocumab were recently published in the New England Journal of Medicine (see here and here). See this story by Larry Husten for the details. Evolocumab and alirocumab are monoclonal antibodies that are in development and are seeking FDA approval based on LDL-cholesterol reduction this year.  The two studies were not designed to answer the question of whether evolocumab and alirocumab prevent cardiovascular events. Rather, the studies measured LDL reduction and tabulated adverse events over a 52- or 78-week time period. Among the adverse events being tabulated were cardiovascular events and there were fewer cardiovascular events in the patients who were in the evolocumab and alirocumab groups, as compared to patients who received placebo or usual care. One of the studies had prespecified an exploratory analysis of cardiovascular events. For the other study the investigators did a post hoc analysis of certain cardiovascular events. Neither study was powered (i.e., big and long enough) to provide a reliable estimate of the benefits of these drugs in reducing heart attacks, strokes and deaths. In other words, statistically speaking the studies were pretty thin gruel and the companies as well as the investigators acknowledge that fact. So, as of now, we really do not know that these drugs reduce the risk of cardiovascular events, let alone by how much. Nor do we really know how safe the drugs are. All these studies tell us is that as of now these drugs appear to be progressing satisfactorily along the path to approval and we just have to be patient for a couple of years until the results of the outcomes trials are available.
Fortunately, the sponsors have started large cardiovascular outcomes trials in high risk patients (e.g., the alirocumab trial will involve 18,000 patients and a minimum of 1613 primary endpoint events and a minimum two year followup — see here for a description of the trial).
I suggest taking a look at this short video of Harlan Krumholz speaking from the conference — I completely agree with his comments (website registration may be required). I also agree with the editorial by Donald Lloyd-Jones and Neil Stone, in which they state:

The ODYSSEY LONG TERM and OSLER studies whet our appetites for further results that show cardiovascular benefit and documented safety, even at substantially lower LDL cholesterol ranges than achieved before. However, it would be premature to endorse these drugs for widespread use before the ongoing randomized trials, appropriately powered for primary end-point analysis and safety assessment, are available. Reports from several lipid treatment trials provide important object lessons in this regard. Two trials of niacin revealed lower levels of LDL cholesterol and lipoprotein(a) when niacin was added to statin therapy but no net clinical benefit and very worrisome signals of harm. A randomized, controlled trial of torcetrapib reminds us that “off-target” effects can scuttle a promising drug. And the recent long-awaited presentation of results of a trial in which ezetimibe was added to moderate-intensity statin therapy in high-risk patients showed only modest benefit, though with excellent safety.

Advertising LVADs

Advanced heart failure is a debilitating and lifethreatening disease that has become increasingly common as our population ages. Patients who have reached a point where their disease threatens their survival are not always candidates for heart transplantation. Even for those that are, only a limited number of donor hearts are available. In the last two decades, implantable pumps to supplement the heart’s function have become available. A left ventricular assist device (LVAD) is a mechanical pump that is implanted in heart failure patients to help the heart’s left ventricle pump blood throughout the body. An LVAD can be used as either a “bridge-to-transplant” to help a patient survive until a donor heart becomes available, or as “destination therapy,” to provide long-term support in patients who are not candidates for a transplant. An LVAD can in some cases prolong the life of heart failure patients whose symptoms can no longer be controlled with medications.

As with any other medical intervention, there are risks and burdens associated with LVAD implantation. The medical risks of the procedure include bleeding, development of blood clots, infection, respiratory failure, kidney failure, stroke, and device failure. LVAD patients must be connected to electricity at all times and are advised not to drive. Each LVAD patient must have a dedicated caregiver to assist with batteries, changing dressings, transportation, and activities of daily living. Heart failure patients often suffer from other medical problems that are not alleviated by LVAD placement. Quite a bit of emotional stress and in some cases financial stress is involved. In addition to heart failure cardiologists and cardiac surgeons, social workers and in some cases bioethicists and palliative medicine specialists meet with the patient to ensure that he or she understands the risks, benefits and alternatives to device placement. The patient must be in a position to make a well-informed decision as to whether to have an LVAD implanted, and it is not uncommon for patients to decline the procedure.

It must be recognized that cardiac surgery, including LVAD implantation, is big business for many medical centers. I was reminded of this when I received the Fall 2014 edition of Center Scope, the newsletter sent to patients and former patients of Medstar Washington Hospital Center (WHC), Washington, DC. I have embedded the newsletter below. The cover story focuses on a 66-year-old patient named Alberto Gomez, who received an LVAD at Washington Hospital Center.  Mr. Gomez appears to be a somewhat atypical patient, in that he had enjoyed excellent health up until suddenly developing extreme fatigue and being diagnosed with advanced heart failure. In any case, Mr. Gomez seems to be a great guy, and I want to make clear that I do not intend to criticize him at all. Rather, my beef is with the way the public affairs & marketing department of WHC, which produces Center Scope, has used Mr. Gomez’s story to spin a happy tale in which “hope,” “determination,” and “faith” are the only things a person needs to manage serious illness.

Alberto’s mental strength and determination served him well. He did not need a blood transfusion during surgery, an often needed measure, and declined pain medication in recovery. And when a stroke he suffered after discharge initially left him with weakness and speech deficits, Alberto overcame them with hard work and perseverance. Currently, Alberto is on a transplant list for a new heart, which doesn’t stop him from living life. “I stay very busy,” he shares. “And I have no time for complaining.”

While Alberto’s heart now requires a LVAD to ensure proper function, his heart needs no assistance in dispensing generosity, kindness and faith. Since recovering from surgery, Alberto has made it a priority to return to the Hospital Center to visit with patients facing similar procedures. “I share my experiences,” Alberto says. “I pray with them and I cry with them. I tell them to trust in the doctors and the technology.”

I’m very glad that Mr. Gomez is doing well. However, I couldn’t help thinking that the message (from WHC, not Mr. Gomez) that a positive attitude can conquer all is a bit insulting to the many LVAD patients who don’t do well. Were their complications — or their need for pain medication — due to lack of determination?

At the end of the story is the following sentence:  “For more information on our heart failure services, visit MedStarHeartInstitute.org/Trust.” I thought to myself that even though the story consisted of one long human interest anecdote, at least at this link I can find some more objective information. On going to the indicated webpage, however, I was disappointed to find only a shortened version of Mr. Gomez’s story and a link to the full version. (The WHC website does have some information on heart failure and LVADs, but I had to click around a bit in order to find it.) I get that hospitals want to advertise their services, but my message for Washington Hospital Center is, how about a little more objective information and a little less schmaltz.

 

IMPROVE-IT trial

The long-awaited IMPROVE-IT trial was presented last month at the American Heart Association Scientific Sessions. Here are the presentation slides:

IMPROVE-IT was a trial that tested the ability of ezetimibe (Zetia) to lower the risk of heart attacks and strokes when added to simvastatin. See Larry Husten’s background post here, and if you type “ezetimibe” in the search box on this blog or on the Gooznews blog, you will find some previous posts of mine relating to ezetimibe. I admit I was a bit surprised that the trial was positive. I was expecting it to be negative, based on the negative results of the ENHANCE trial. Still, the benefit was small, a 6.4% reduction in risk of the primary endpoint (composed of cardiovascular death, heart attack, unstable angina requiring hospitalization, coronary revascularization, and stroke). In the high-risk trial participants — all patients who had been hospitalized for acute coronary syndrome within the 10 days before randomization — this translated to a 2% absolute benefit over 7 years. Of note, there was no reduction in all-cause or cardiovascular mortality.

I only want to make a few comments now, but I intend to write more when the trial is published. First, a 6.4% reduction is risk is a very small benefit, and many people would only consider that reduction in risk meaningful in a high risk population. Second, it is regrettable that we had to wait 12 years after the drug’s approval to find out whether it improves outcomes.

Here are great summaries by Larry Husten and Matt Herper. And here is a video of Harlan Krumholz giving his take on the results.

Addendum, May 5, 2015:  Unfortunately, the GoozNews blog is no longer up on the web. I asked Merrill Goozner what happened and he said he decided to stop paying the annual fee for the website. So the posts I wrote on ezetimibe for GoozNews are no longer up.

American Heart Association journal announces new Patient Viewpoints

The following is reposted from e-patients.net.

The American Heart Association journal Circulation: Cardiovascular Quality and Outcomes has announced a new Patient or Caregiver Viewpoint section in the journal. Viewpoints will be authored by patients or their caregivers and will discuss the patient’s experience of heart disease, stroke, or other cardiovascular disease and their interactions with the healthcare system.

As Harlan Krumholz and I explain in an Editor’s Note, the editors of the journal hope that Viewpoints “will contain insights from the patient’s perspective along with suggestions on how to improve clinical care and healthcare delivery.”

The first Viewpoint, by a heart disease patient, discusses how he experienced interactions with his physicians over whether he should start a blood pressure medication and his thoughts on how physicians and patients could work together in a manner consistent with the patient’s values and goals.

Viewpoints will contain a minimum of medical jargon and will be freely accessible to the public. The journal hopes to make these articles a regular feature. If you are a patient living with or at risk of cardiovascular disease, or a friend or family member of such a patient, please consider submitting a Viewpoint. Instructions for authors are posted on the journal’s website.

Input needed on stent decision aid

I have a post up on e-patients.net (the Society for Participatory Medicine blog) discussing a draft decision aid that some PCORI-funded researchers are developing to help patients choose between bare metal stents and drug-eluting stents. Here’s an excerpt:

The study is in the beginning phase, and the researchers are engaging patients in focus groups to better understand what factors are most important to them in choosing a stent. The focus groups will also involve asking patients how they prefer the information to be presented (e.g., in words, graphs, some combination of the two, and so forth). Later, the decision aid will be tested at two hospitals to see if it improves patient understanding and satisfaction, and if the use of the decision aid changes the percentages of bare metal stents and drug-eluting stents received by the patients.

Dr. Chhatriwalla is very interested in getting feedback from patients and others on the current drafts of the decision aid (two different versions) and has asked SPM to help circulate them. You do not need to be a heart disease patient to participate — the researchers are interested in a wide range of viewpoints. Please take a look at both of them (posted below) and send your comments to Dr. Chhatriwalla at achhatriwalla@saint-lukes.org.

(Click to enlarge.)

DA-option-1-thumbnailDA-option-2-thumbnail

New series of articles in Circulation: Cardiovascular Quality and Outcomes

Circulation: Cardiovascular Quality and Outcomes will be publishing a new series of articles called narratives, which will be written by patients or by their family, friends or caregivers.

Narratives: The purpose of this series is to further understanding of patients’ experience of cardiovascular disease. These articles will be written by patients, or by their family members, caregivers, or friends. The articles will explore the effects of illness and treatment on patients’ lives and on their relationships with family, friends, caregivers, and health care providers. They will often discuss aspects of a condition that are important to patients but may not be fully appreciated by clinicians. We are especially interested in publishing narratives that contain lessons on the strengths and weaknesses of our health care system. They may, for example, be designed to help health care providers become aware of problems in communication of information, decision making, care coordination, access, cost, timeliness, safety, equity, and quality of care.

More information is available here. Submit your article here.

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