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Posts Tagged FDA

## It’s time for true transparency of clinical trials data

What makes a health professional science-based? We advocate for evaluations of treatments, and treatment decisions, based on the best research methods. We compile evidence based on fair trials that minimize the risks of bias. And, importantly, we consider this evidence in the context of the plausibility of the treatment. The fact is, it’s actually not that hard to get a positive result in a trial, especially when it’s sloppily done or biased.  And there are many ways to design a trial to demonstrate positive results in some subgroup, as Kimball Atwood pointed out earlier this week. And even when a trial is well done, there remains the risk of error simply due to chance alone. So to sort out true treatment effects, from fake effects, two key steps are helpful in reviewing the evidence.

1. Take prior probability into account when assessing data. While a detailed explanation of Bayes Theorem could take several posts, consider prior probability this way: Any test has flaws and limitations. Tests give probabilities based on the test method itself, not on what is being tested. Consequently, in order to evaluate the probability of “x” given a test result, we must incorporate the pre-test probability of “x”. Bayesian analysis uses any existing data, plus the data collected in the test, to give a prediction that factors in prior probabilities. It’s part of the reason why most published research findings are false.

2. Use systematic reviews to evaluate all the evidence. The best way to answer a specific clinical question is to collect all the potentially relevant information in a structured way, consider its quality, analyze it according to predetermined criteria, and then draw conclusions. A systematic review reduces the risk of cherry picking and author bias, compared to non-systematic data-collection or general literature reviews of evidence. A well-conducted systematic review will give us an answer based on the totality of evidence available, and is the best possible answer for a given question.

These two steps are critically important, and so have been discussed repeatedly by the contributors to this blog. What is obvious, but perhaps not as well understood, is how our reviews can still be significantly flawed, despite best efforts. In order for our evaluation to accurately consider prior probability, and to be systematic, we need all the evidence. Unfortunately, that’s not always possible if clinical trials remains unpublished or are otherwise inaccessible. There is good evidence to show that negative studies are less likely to be published than positive studies. Sometimes called the “file drawer” effect, it’s not solely the fault of investigators, as journals seeking positive results may decline to publish negative studies. But unless these studies are found, systematic reviews are more likely to miss negative data, which means there’s the risk of bias in favor of an intervention. How bad is the problem? We really have no complete way to know, for any particular clinical question, just how much is missing or buried. This is a problem that has confounded researchers and authors of systematic reviews for decades. (more…)

## Who’s to Blame for Drug Shortages?

All the best effort to practice science-based medicine are for naught when the optimal treatment is unavailable. And that’s increasingly the case – even for life-threatening illnesses. Shortages of prescription drugs, including cancer drugs, seem more frequent and more significant than at any time in the past. Just recently manufacturing deficiencies at a large U.S.-based contract drug manufacturer meant that over a dozen drugs stopped being produced. This lead to extensive media coverage, speculating on the causes and implications of what seems like a growing problem. So who’s to blame? (more…)

Posted in: Pharmaceuticals, Politics and Regulation

## Breast implants and anaplastic large cell lymphoma (ALCL): Is there a link?

I must admit that I have a bit of a love-hate relationship with breast implants. On the one hand, as a breast cancer surgeon, I see them as a major benefit to my patients who are unfortunate enough to require mastectomy in order to control their disease. The armamentarium of techniques for reconstructing breasts after mastectomy generally falls into one of two categories, either various form of muscle flaps or breast implants. However, some women are, for various reasons, not eligible for various muscle flap reconstructions. That leaves either breast implants–or nothing. Certainly, some women are perfectly fine with no reconstruction after mastectomy, but many, if not most, women are not. For these women, it would be difficult to overstate how much of a boon to body image and self-esteem reconstruction can be, particularly given how much better at it plastic surgeons have become over the last couple of decades.

On the other hand, breast implants make my life as a breast cancer surgeon more difficult for a variety of reasons. First, they tend to make mammography more difficult by obscuring part of the breast, thus decreasing the sensitivity of mammography. Good mammography facilities can get around this to some extent by using various displacement techniques, but it takes some effort, and it doesn’t completely correct the problems that implants cause for mammographic screening. Moreover, when a woman who has had implants placed for cosmetic reasons comes to see me for a breast mass or an abnormal mammogram, the presence of the implants can complicate treatment decisions. If the abnormality or mass is close to the implant, we worry about rupturing it in the process, particularly if the implant is not below the pectoralis major muscle. Even when the implant is subpectoral, the muscle overlying it frequently ends up being so stretched out that the muscle in essence forms part of the capsule around the implant and ends up being a lot thinner than you might expect. Let me tell you, my anal sphincter tone is always much tighter when operating near an implant, particularly a silicone implant. True, I’m perfectly capable of removing an implant if it’s accidentally ruptured, but such an outcome is not desirable, particularly with silicone implants, where cleaning up the leaking silicone can be difficult.

It doesn’t help that silicone breast implants have been the subject of controversy since the late 1980s and early 1990s, when thousands of women with silicone implants reported a variety of ailments, including autoimmune disease and a variety of other systemic illnesses. These reports led to a rash of lawsuits and, ultimately, the banning of silicone breast implants for general use in 1992. After that, silicone breast implants were only permitted in women requiring breast reconstruction or women enrolled in clinical trials studying breast implants. This ban was partially lifted in 2006, as evidence accumulated that the claims of autoimmune diseases and increased cancer risk due to silicone breast implants were not supported by clinical and scientific evidence and two products made by Allergan Corp. (formerly Inamed Corp.) and Mentor Corp. Not surprisingly, given that the furor over silicone breast implants as a cause of autoimmune and other systemic diseases is based on about as much solid scientific evidence as the antivaccine furor over vaccines as a cause of the “autism epidemic,” there was widespread criticism of this decision. Even now, it is not difficult to find articles about breast implants with titles like Breast Implants: America’s Silent Epidemic and websites like the Humantics Foundation and Toxic Breast Implants . I do note, however, that the number of such sites and articles does appear to be declining and, at least to my impression, seems to have decreased markedly over the last 10 years or so.

Having reviewed the literature and found evidence for a link between silicone breast implants and the systemic diseases attributed to them to be incredibly weak at best, I had little problem with the FDA’s decision. Actually, the only thing I had a problem with at the time, my opinions of how breast implants interfere with breast cancer detection and treatment notwithstanding, is that the FDA was probably being more cautious than the evidence warranted after 14 years.

Was I wrong?
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## Avastin and metastatic breast cancer: When science-based medicine collides with FDA regulation

One of the most frustrating aspects of taking care of cancer patients is that in general, with only a few specific exceptions, we do not have good curative therapies for patients with stage IV cancer, particularly solid tumors. Consequently, patients with stage IV disease are viewed as “incurable” because, the vast majority of the time, they are incurable. Over the years, we have thrown everything but the kitchen sink at patients with stage IV disease, largely with dissapointing results. That’s not to say that the few specific exceptions to which I alluded are not a reason for hope. After all, patients with colorectal cancer and liver metastases used to have a median survival of around 6 months, but these days, with newer chemotherapeutic regimens like FOLFOX plus Avastin, median survival has more than tripled. While expecting to live less than two years is cold comfort to cancer patients with this particular clinical situation, the prognosis is far better than it was.

Of course, I specifically mentioned Avastin because it’s been in the news a lot recently with respect to my area of clinical specialty, breast cancer. Specifically, beginning in July there started appearing a spate of stories about the FDA considering revoking the approval of Avastin for advanced breast cancer based on recent studies that demonstrate that it does not prolong survival in these patients. Many lay people and patients find this reconsideration of Avastin to be quite puzzling, given that the drug was granted accelerated approval in 2008 and has since gone on to be used fairly widely. Given that the case of Avastin in breast cancer is rapidly becoming a classic case study of how messy science-based medicine can be when practiced in the public eye and debated among pharmaceutical companies, the government, and patient advocacy groups.
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## Off-Label Use of Prescription Drugs

A recent survey of 599 primary care physicians and 600 psychiatrists found that:

The adjusted response rate was 47%, respondents were similar to non-respondents, and physicians commonly prescribed the drugs examined. The average respondent accurately identified the FDA-approval status of just over half of the drug-indication pairs queried (mean 55%; median 57%). Accuracy increased modestly (mean 60%, median 63%) when limited to drugs the respondent reported having prescribed during the previous 12 months. There was a strong association between physicians’ belief that an indication was FDA-approved and greater evidence supporting efficacy for that use (Spearman’s 0.74, p < 0.001). However, 41% of physicians believed at least one drug-indication pair with uncertain or no supporting evidence (e.g., quetiapine [Seroquel®] for dementia with agitation) was FDA approved.

These results are interesting, but deserve to be dissected a bit further. Taken at face value they indicate that physicians need better education regarding the FDA indications and (more importantly) the evidence-base for commonly prescribed drugs. This is an uncontroversial recommendation, and I personally strongly advocate more thorough physician continuing medical education.

Of course, at SBM we have to also dissect the weaknesses of any study we examine. This was a voluntary survey with a 47% response rate, which opens the door for significant responder bias. The survey does not broadly represent different specialties and therefore its relevance beyond primary care and psychiatry is uncertain. The details of the study may also have greatly influenced the outcome.

For example, one of the drug-indication pairs was gabapentin for diabetic peripheral neuropathy. Gabapentin is not specifically indicated for diabetic neuropathy, but it is indicated for post-herpetic neuralgia. Both conditions are forms of neuropathic pain, and it is highly scientifically plausible for a treatment of one condition to also be effective for the other. In fact, there is strong evidence that gabapentin is effective for diabetic neuropathy, and it is commonly prescribed for this condition (in fact insurance companies often require that it is first line treatment as it is now available generically and is therefore less expensive than newer drugs that are indicated specifically for diabetic neuropathy). In other words, this was one of the easiest mistakes to make.

Posted in: Pharmaceuticals

## Is Tylenol Safe?

Tylenol (acetaminophen, also known as paracetamol outside the US) has been in the news recently. Most of the stories I’ve seen have been accurate, but I’ve run across a couple of people who misunderstood what they read. I thought I’d try to put the record straight.

An FDA advisory panel has recommended reducing the maximum allowed single dose from 1000 mg to 650 mg in over-the-counter acetaminophen products. The 1000 mg dose would be available by prescription only. They also recommended eliminating painkillers like Percocet and Vicodin that contain a combination of a narcotic and acetaminophen. They did not recommend removing acetaminophen from over-the-counter cold remedies, cough medicines and similar products that combine acetaminophen with other drugs. Advisory panel recommendations are not binding, but the FDA usually follows them.

Some people got the impression that the FDA had just discovered that acetaminophen can be dangerous. No, we always knew that. The danger is when you take too much: it can damage the liver. The “new” information is just that acetaminophen overdose is now the leading cause of liver damage, causing an estimated 1600 cases of liver failure each year. (more…)

## Tactless About TACT: Critiques Without Substance Should Be Abandoned

In May 2008, the article “Why the NIH Trial to Assess Chelation Therapy (TACT) Should Be Abandoned” was published online in the Medscape Journal of Medicine. The authors included two of our own SBM bloggers, Kimball Atwood and Wallace Sampson, along with Elizabeth Woeckner and Robert Baratz. It showed that the existing evidence on treating heart disease with IV chelation did not justify further study, and that the TACT trial was questionable on several ethical points. Their ethical concerns were taken seriously enough that enrollment in the trial was put on hold pending an investigation. It has now been re-opened after a few band-aids were applied to the ethical concerns. The scientific concerns were never addressed.

I have seen many critiques of the Atwood study, and not a single one has offered any cogent criticism of its factual content or reasoning. Most of them could have been written by someone who had not bothered to read beyond the title. Their arguments can be boiled down to a few puerile points that can be further simplified to:

(1) I believe the testimonial evidence that chelation works.
(2) Atwood and his co-authors are bad guys.

Now Beth Clay has chimed in with an article entitled “Study of Chelation Therapy Should Not Be Abandoned.” I found it truly painful to read, but even the worst has some value as a bad example. Clay’s article could be used for a game of “Count the Errors.” I will point out some of them below. (more…)

## Counterfeit Drugs: A Growing Global Health Crisis

A resistant strain of bacteria –created by partially effective counterfeit antibiotics – doesn’t need a VISA and passport to get to the U.S.

-    Paul Orhii, National Agency for Food and Drug Administration and Control, Nigeria

I attended a conference in DC yesterday called, “The Global Impact of Fake Medicine.” Although I had initially wondered if homeopathy and the supplement industry would be the subjects of discussion, I quickly realized that there was another world of medical fraud that I hadn’t previously considered: counterfeit pharmaceuticals.

Just as designer goods have low-cost knock-offs, so too do pharmaceuticals and medical devices. Unfortunately, counterfeit medical products are a higher risk proposition – perhaps causing the death of hundreds of thousands of people worldwide each year.

It is difficult to quantify the international morbidity and mortality toll of counterfeit drugs – there have been no comprehensive global studies to determine the prevalence and collateral damage of the problem.  But I found these data points of interest (they were in the slide decks presented at the conference):
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## FDA approval of drugs and transparency in clinical trial results

Note: The reason that I am posting today rather than my usual Monday slot is because the article I discuss here was embargoed until last night. Consequently, I asked Harriet if she would trade days with me this week, and she was kind enough to do so.

One thing that science relies on almost absolutely is transparency. Because one of the most important aspects of science is the testing of new results by other investigators to see if they hold up, the diligent recording of scientific results is critical, but even more important is the publication of results. Indeed, the most important peer review is not the peer review that occurs before publication. After all, that peer review usually consists of an editor and anywhere from one to four peer reviewers on average. Most articles that I have published were reviewed by two or three reviewers. No, the most important peer review is what occurs after a scientist’s results are published. Then, all interested scientists in the field who read the article can look for any weakness in methodology, data analysis, or interpretations. They can also attempt to replicate it, usually as a prelude to trying to build on it.

Arguably nowhere is this transparency quite as critical as in the world of clinical trials. The reason is that medications are approved on the basis of these trials; physicians choose treatments; and different medications become accepted as the standard of care. Physicians rely on these trials, as do regulatory bodies. Moreover, there is also the issue of publication bias. It is known that “positive” trials, trials in which the study medication or treatment is found to be either efficacious compared to a placebo or more efficacious than the older drug or treatment it is to replace, are more likely to be published. That is why, more and more, steps are being taken to assure that all clinical trial results are made publicly available. For example, federal law requires that all federally-funded clinical trials be registered at ClinicalTrials.gov at their inception, and peer-reviewed journals will not publish the results of a clinical trial if it hasn’t been registered there. Also, beginning September 27, 2008, the US Food and Drug Administration Amendments Act of 2007 (FDAAA) will require that clinical trials results be made publicly available on the Internet through an expanded “registry and results data bank,” described thusly. Under FDAAA, enrollment and outcomes data from trials of drugs, biologics, and devices (excluding phase I trials) must appear in an open repository associated with the trial’s registration, generally within a year of the trial’s completion, whether or not these results have been published. Although there are some practical issues over this law, for example determining how much information can be disseminated this way without constituting prior publication, which is normally a reason to disqualify a manuscript from publication.
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## Mercury Must Be Bad – If Not in Vaccines, In Teeth

Those of us who are baby boomers or older can remember playing with mercury when we were young. The thermometer broke, and you pushed the little globules around. Or you fooled around with the stuff in science class. My husband says he used to get mercury to flow over the surface of a dime and make it look really shiny. Who knew our old playmate would turn out to be such a bugaboo?

The real dangers of mercury have been recognized. Guidelines have been published to limit exposure. Instructions for safe cleanup of mercury spills are available online. This is good. Other developments are not so good. Scaremongers have demonized mercury and blamed it for everything from autism to Alzheimer’s.

Just when you thought the mercury/autism scare was finally subsiding, another mercury scare has resurfaced. The alarm has been raised (again!) about the mercury in amalgam fillings. (more…)

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