Seeking Answers to the Questions That Plague Healthcare Epidemiologists


With greater emphasis than ever before on evidence-based practices and implementation science, researchers are working diligently to provide answers to questions that have been plaguing the healthcare epidemiology and infection prevention community. Recognizing that there are more questions than answers, the Society for Healthcare Epidemiology of America (SHEA) surveyed its members several years ago measure their perceptions of gaps in the healthcare epidemiology knowledge base and members priorities for SHEA research goals. The society also assessed whether members would be willing to participate in consortia to address identified gaps in knowledge, and evaluated the need for training for the next generation of investigators in the field of healthcare epidemiology.

By Kelly M. Pyrek

With greater emphasis than ever before on evidence-based practices and implementation science, researchers are working diligently to provide answers to questions that have been plaguing the healthcare epidemiology and infection prevention community.

Recognizing that there are more questions than answers, the Society for Healthcare Epidemiology of America (SHEA) surveyed its members several years ago measure their perceptions of gaps in the healthcare epidemiology knowledge base and members priorities for SHEA research goals. The society also assessed whether members would be willing to participate in consortia to address identified gaps in knowledge, and evaluated the need for training for the next generation of investigators in the field of healthcare epidemiology.

More than 1,200 SHEA members identified the following issues as important for the society's Research Committee: setting the scientific agenda for healthcare epidemiology, developing collaborative infrastructure to conduct research, and developing funding mechanisms for research. Respondents ranked multidrugresistant gramnegative organisms, antimicrobial stewardship, methicillinresistant Staphylococcus aureus, adherence to effective hand hygiene guidelines, and Clostridium difficile infections as the most important scientific issues facing the field. Respondents ranked inadequate project funding, lack of protected time for research, and inability to obtain a grant, contract, and/or outside funding as the most significant barriers to conducting research. More than 92 percent of respondents supported creating a SHEA research consortium; more than 40 percent said they would participate even if no additional funding were available; and nearly 90 percent identified developing research training as a key function for SHEA. Members of the for the SHEA Research Committee say these data provide a road map for the next decade. (Henderson and Bonten, et al. 2010)

But there are challenges. SHEA members identified the top four barriers identified relate directly to insufficient resources for basic science: inadequate funding for specific projects; lack of protected time for research;  inability to obtain grant, contract and/or outside funding; and an inadequate number of personnel in the field of healthcare epidemiology.

We spoke to David K. Henderson, MD, deputy director for clinical care at the Clinical Center of the National Institutes of Health, about his perspectives relating to the efforts that researchers are making toward better informing healthcare epidemiology and infection prevention through rigorous studies:

Q: What kind of progress has been made since the SHEA Research Consortium was founded?
A: There have been a number of elegant, very carefully designed and conducted studies that have addressed important questions in healthcare epidemiology. Anthony Harris' study of gowning and gloving, which is under consideration for publication, was a carefully designed clustered, randomized trial. Those kinds of studies are sorely needed in this field that has operated for a long time with substantial gaps in our understanding of the epidemiology and pathogenesis of the infections we are trying to prevent. Susan Huangs recently published New England Journal of Medicine paper is another excellent example.

Q: Are other key areas of research being addressed satisfactorily?
A: I think you can always use more research. I am aware of studies that have been completed, some that are in the process of being conducted, as well as some still in the design stage.  These are all studies that address aspects of the questions that have plagued us in the healthcare epidemiology field for 30 years. We are finally going to get some answers to those questions and it will give us a new direction.

Q: At scientific meetings it is acknowledged that what researchers don't know is greater than what they do know --  will there ever be a time when we have more answers than questions?
A: The nature of science is such that every time you answer a question it usually poses three or four more. That's one of the wonderful things about science. If you look at where healthcare epidemiology is now, making a comparison to say endocrinology, where endocrinologists now have the ability to say with enormous amount of precision and certainty what is happening in any given disease. We're not there yet. Our laboratory, unlike theirs, is a very poorly controlled environment in most instances -- our laboratory is the hospital. So there are formidable barriers to overcome even to conduct these studies, and some of the new leaders in healthcare epidemiology both in the U.S. and abroad are really attacking some of those issues in very intelligent ways. I think that they are going to move the discipline forward. Will we ever get to the end? I don't think so.  We still have a lot to learn but we have learned a great deal more in the last four or five years -- for example, the role of the environment is very fertile ground that researchers are trying to plow now.

Q: A presentation at this year's SHEA Spring Conference debated whether hand hygiene or environmental hygiene was more important -- are people making too many presumptions about the evidence here?
A: If you look at Semmelweis's original data it's pretty clear that his one intervention had a dramatic effect. Clever epidemiologists will argue that it was in an outbreak setting and maybe that's not the same as an endemic setting these issues have been fodder for many discussions that have taken place over the years.  Hand hygiene is a significant part of healthcare epidemiology, and for reasons I don't understand, it's evident that some of our colleagues don't take it as seriously as they ought to. It puzzles me that we have not been able to successfully integrate hand hygiene into every aspect of patient care. One of the reasons to have these point/counterpoint conversations is to come away with an appreciation that maybe both components -- hand hygiene and environmental hygiene -- are important. I think the inanimate environment in the healthcare setting has probably been given short shrift until the last three or four years.  When healthcare epidemiology grew up as a discipline in the UK in the 1960s, it focused on the environment, not on healthcare providers as important in the transmission of healthcare-associated infections. Then the CDC got involved in the 1970s and 1980s and we learned a lot about the basic epidemiology of healthcare-associated infections (HAIs).  Clinician investigators started focusing on healthcare personnel, almost to the total exclusion of the environment. And that probably wasn't smart either. But this recent interest in the environment has come about for a number of reasons. One is that people have again started becoming worried about it, especially in the hospitals such as mine where we have numerous patients who are immunosuppressed and are at risk for acquiring virtually all healthcare-associated pathogens. And now we have all of these new tools and technologies -- some of them are expensive, some of them are technically difficult to use, but many of them are effective in decreasing the bioburden. We are waiting for efficacy studies; one was just published by investigators at Johns Hopkins and I think another is being conducted by investigators at Duke, among others. These studies will tell us whether the juice is worth the squeeze. It's very hard, because of the complexity of our laboratory, to isolate one factor and say yes, this disinfection strategy decreased the rate of healthcare-associated infection. It's extremely hard to do that. But hard does not mean impossible, and I think some of these newer studies are going to get there. They will help us understand the extent to which these new strategies and novel interventions may actually make the environment safer for our patients.

Q: Practitioners live and die by the evidence and they sometimes struggle with evaluating it amidst the 'white noise' in the marketplace, don't they?
A: We live in a free-market economy and people are marketing their products and claiming they have evidence that they work. Often those are studies that are poorly designed or designed by the manufacturer to produce a favorable result. In this day and age it's also important to demonstrate cost effectiveness -- we may be able to show that one of these strategies reduces bioburden by 10 percent, but is that biologically relevant? Often, no one may know the answer to that question. So if the absolute sine qua non would be to show you had fewer environmentally spawned HAIs, but since we can't detect which are and which are not environmentally spawned, it's complicated.

Q: At what point do studies in the literature gain critical mass and it becomes clear there is a conclusion that can be trusted?
A: Let's imagine you and I are infectious disease physicians and we come across a patient with streptococcal cellulitis; we give the patient penicillin and the patient gets well immediately. We have another patient whom we didn't treat with penicillin previously and that patient got sepsis and died. And so the next four patients we see with streptococcal cellulitis, we give them penicillin; and they get well. That's not a randomized, controlled trial, it wouldn't make anyone's evidence list, and it would never get published. But Is it good evidence? You bet. But it's not always that easy. I've been wanting for years to do a randomized, controlled trial of the efficacy of parachutes if you jump out of airplanes but I can't find any volunteers. So I am a fan of the rigor of the process of grading the evidence as the CDC does, and this is the way all of the Cochrane reviews are conducted, and they are useful. However, I think they miss a lot of important things in the process of doing that. So I think individual folks try to grade the evidence in their own minds as well, based on their clinical experiences. For example a study conducted at a large county hospital where the patient population is mostly from the gun-and-knife club, would likely have limited relevance in my organization, even if it shows a highly statistically significant result.   One has to consider a variety of factors in evaluating the evidence produced by a study including the setting in which it is conducted -- the patient population being admitted and treated, their underlying diseases, the extent to which the patients are immunosuppressed and a variety of other factors. So as you read the literature, those are the kinds of variables you are looking at, thinking to yourself, 'Is this relevant to my environment?' If you disregard too much data, you might miss key pieces of information.

Q: When there are breaches in practice, is it a knowledge gap or an implementation gap? Or other factors such as cutting corners due to crushing workloads, etc.?
A: I suspect it's all of the above. The paper we had submitted that discusses the Semelweiss reflex, asserts that in our profession we have the ability to ignore evidence if it doesn't fit with our current way of thinking. I think that's part of it -- people cut corners, people sometimes are ignorant of information, but I am particularly troubled about ignoring hand hygiene. The data are quite compelling that hand hygiene has a profound impact; it may not prevent every infection, but it's going to prevent a lot of infections if we can do it appropriately and in a timely fashion. As a discipline, almost across the board in the United States, clinicians are able to engage in hand hygiene, on average, about 40 percent of the time. That's horrifying.

Q: What do you think about the importance of balancing old-school interventions with the newer disinfection technologies?
A: Let's suppose the environment turns out to be much more important than we always thought it was -- then this new technology will be very useful. But one would have thought with the extent to which these technologies are being used now that we might be seeing some really dramatic changes if that were the case.  Whenever I talk about new technologies I always say be skeptical, look carefully for efficacy, and make certain the efficacy you are looking at has relevance to your environment, and then look for cost effectiveness, and make certain it's worth the investment. Sometimes if you have people dying in your hospital, you try anything and everything.


Henderson DK, Bonten M, Fishman NO, Gordon S, Harbarth S, Harris AD, Lautenbach E, Palmore TN, Perencevich EN, Perl TM, Platt R, Saint S, Samore M, Sherertz R, Weber DJ, Weinstein RA, Deloney V, Sinaii N. Charting the course for the future of science in healthcare epidemiology: Results of a survey of the membership of The Society of Healthcare Epidemiology of America. Infect Control Hosp Epidemiol. 2010; 31(7): 669-75.

A Golden Opportunity for Healthcare Epidemiology

In an editorial published in Infection Control and Hospital Epidemiology, "A DoubleEdged Sword and a Golden Opportunity for Healthcare Epidemiology," Robert A. Weinstein, MD, and David K. Henderson, MD, outline the numerous challenges and opportunities for healthcare epidemiologists who find themselves thrust unto the limelight as a renewed focus on preventing HAIs is being mandated by stakeholders.

As Weinstein and Henderson (2009) explain, "To achieve further successes, however, we will need a substantial investment in basic science, translational medicine  and epidemiology. Compared with some other disciplines in infectious diseases and microbiology, healthcare epidemiology has far lesssolid scientific underpinnings. We simply must conduct the studies that characterize the epidemiology of endemic healthcareassociated infections at a granular level, to provide a clear understanding of which risk factors operate in which settings and which interventions are more, or even most, likely to be successful. In an era when we are beginning to discuss the benefits of 'personalized medicine,' a broad approach will not lend substantial insight into the myriad complex issues that actually define the epidemiology and pathogenesis of healthcareassociated infections. A broadbrush approach will not allow us to generate new hypotheses that will result in the development of successful interventional strategies for healthcareassociated infections. For example, despite the fact that molecular studies have characterized Clostridium difficile in excruciating detail, even in the year 2008 we have a remarkably limited understanding of the factors that influence the spread of C. difficile in the healthcare environment. Do the mechanisms of transmission vary by patient population or institutional demographics? What is the role of immunosuppression? What is the role of antimicrobial stewardship in the institution? Can specific antimicrobials or antimicrobial classes be definitively incriminated? What is the contribution of the hospital inanimate environment to the spread of these organisms? What are the benefits or drawbacks of alternate cleaning strategies? How important is hand hygiene to the prevention of transmission in differing institutional settings? Whereas these are complex, multi-factorial questions, they must be answered for us to achieve the kinds of prevention success that we all desire."

Weinstein and Henderson (2009) continue, "Hundreds of basic, translational, and epidemiological questions need to be answered for us to be able to intervene, both effectively and with precision, to prevent healthcareassociated infections. How is it possible that we could find ourselves in this situation in the 21st century, and what can we do to address these issues? First, we have to be able to identify what we know, what we don't know, and, most importantly, what we need to know to be able to intervene successfully. Simply put, we have to identify the questions that need to be addressed; we must design and implement studies that can provide the scientific foundation for the generation of new prevention hypotheses; and we must test these prevention strategies by carefully designed, basic, translational, epidemiological and behavioral studies that are powered adequately to address these questions and to make distinctions definitively."

A year later, in an article also published in Infection Control and Hospital Epidemiology, Henderson and Palmore (2010) address the gaps in the healthcare epidemiology science base in the areas of pathogenesis, epidemiology, interventions, and study design by noting, "With respect to pathogenesis, we need studies that clarify the precise mechanisms of pathogen acquisition and the specific biological mechanisms of colonization and infection. Similarly, we need a more precise understanding of the role of host factors in colonization and/or infection, including the role of nonspecific, humoral, cellular, and mucosal immunity. We have only the most basic understanding of microbial biofilms, and we need clearer definitions of the chemistry, biology, and ecology of these unique microbial matrices. With respect to epidemiology, we need a basic understanding of the role of the environment, fomites, patients, and healthcare workers hands in the transmission of specific healthcareassociated microbial pathogens. Screening has become a vogue issue, yet we have only the most rudimentary understanding of the optimal body sites at which to try to detect resistant pathogens and of the specific settingsclinical and institutionalin which screening is beneficial. We also need a much more robust understanding of how patterns of antimicrobial use in healthcare institutions influence the development of multidrugresistant organisms, as well as the optimal approach to antimicrobial stewardship. With respect to intervention efficacy, 260 years after the pioneering efforts of Semmelweis, we still do not have an adequate science base regarding hand hygiene and its efficacy. We lack an adequate scientific basis for many of our isolation strategies, and we have very limited information about the scientific basis for decolonization and decontamination as interventional approaches."


Weinstein RA and Henderson DK.  Editorial: A DoubleEdged Sword and a Golden Opportunity for Healthcare Epidemiology. Infect Control Hosp Epidem.  Vol. 30, No. 1. January 2009. 

Henderson DK, Palmore TN. Critical knowledge gaps in the epidemiology and pathophysiology of healthcare-associated infections. Infect Control Hosp Epidemiol. 2010; 31(S1): S4-6;

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