Evolving Issues
Improving Study Design
During the past 20 years, many published reports have described improved outcomes as the result of modifications in basic environmental cleaning. Unfortunately, causal analysis of essentially all of these studies has been greatly hampered by the simultaneous implementation of multiple interventions along with "improved cleaning." This issue is particularly well illustrated by the reports of interventions to minimize healthcare-onset Clostridium difficile infection beginning in the mid-1980s. Although more than 20 quasi-experimental, often-outbreak-associated studies have supported the likely effect of improved environmental hygiene on C. difficile transmission, all of these studies consist of several interventions implemented simultaneously. Because of known as well as additional unevaluated confounding variables in each study, it has been impossible to quantify the true impact of disinfection cleaning on C. difficile transmission.
Even when single environmental intervention cleaning agent change, for example, is pursued, published studies have not separated out the thoroughness of cleaning from the specific cleaning agent being tested. For example, it is possible that the novelty of a new cleaning agent results in better attention to process and increased thoroughness of cleaning that is behavioral in origin, due to the heightened attention surrounding change. This phenomenon has been suggested in other infection prevention activities. To date, none of the clinical studies designed to assess specific disinfectant chemistries—particularly bleach—or application systems such as microfiber have controlled for this phenomenon by monitoring the thoroughness of general cleaning processes in addition to microbiological outcomes. This will be important in future studies.
Furthermore, that many of these studies have been implemented in settings with transiently high rates of transmission of specific pathogens, such as C. difficile and VRE, limits the benefits attributed to any intervention. This is due to the statistical likelihood of regression to the mean following outlier rates.
There also is a need to substantially move environmental hygiene research from evaluation of practice to evaluation of objectively defined and reproducible clinically meaningful outcomes. While many studies have successfully introduced objective process measures for the thoroughness of disinfection cleaning practice and environmental contamination by clinically important bacterial pathogens, there is a need for large, well-conducted studies that use pathogen acquisition and clinical infection as outcomes to quantify the clinical impact of disinfection cleaning agents and thoroughness of practice. Such outcome studies, although logistically more complex and costly, provide critical validation of the value of improving routine disinfection cleaning practice. A few such studies of pathogen acquisition have been performed, but larger, more generalizable ones are needed. For example, further investments can and should be made to conduct studies comparing the effectiveness of various cleaning protocols, practices, agents, and application systems on common healthcare-associated pathogens, such as MRSA, VRE, and Acinetobacter. Such clinical studies should compare new interventions to a standard of thorough, high-compliance, traditional disinfection cleaning based on objective monitoring to separate out process from the effectiveness of the agent or application system.
Fortunately, substantial improvement in HAI research related to choice of study design and analytics, as well as research during nonoutbreak settings, has enabled some estimates of attributable risk due to environmental contamination and patient outcomes. Studies using crossover and cluster-based designs, washout periods between interventions, and advanced evaluations addressing confounding and bias are beginning to provide a quality of research that is far beyond that seen just a few short years ago. Well-designed comparative effectiveness trials are also being pursued. Along with the need to optimize comparative effectiveness, translational research will be needed to quantify the relative clinical value of specific unimodal as well as programmatic interventions to decrease environmental pathogen transmission. Finally, new genomic and polymerase chain reaction–based technologies may provide important insights into the role of the environment in healthcare-associated pathogen transmission.
Additional Challenges
Beyond improved study design and analysis, there are several critical research needs in environmental cleaning and disinfection for healthcare facilities (Table 2).
During the past few years, innovative technologies have been developed that have the potential for providing enhanced environmental surface disinfection. As the economics of healthcare facilities markedly changes in response to accountable care structures, investing in such touchless environmental cleaning systems or making a business case for monitoring and objectively improving the thoroughness of basic disinfection will need to account for trade-offs between the cost of such investments and their ability to increase patient safety. Thus, it is even more imperative that estimates of attributable risk due to environmental contamination and attributable gains due to environmental interventions be pursued. Current monitoring programs (aggressive checklists, UV monitoring, and feedback) that improve the thoroughness of basic disinfection cleaning have shown limited (if any) increase in personnel costs, since they are readily absorbed into current management systems that previously supported visual monitoring. Similarly, new disinfectants or cleaning cloths are generally limited to the change in product costs rather than additional personnel. Nevertheless, justifying the cost of novel technologies, which require new equipment and personnel resources, while there is still a need for personnel to perform basic cleaning will require more reliable estimates of attributable HAI disease reduction once logistical efficiencies are overcome. Future solutions that reduce personnel costs are conceptually possible, but their impact on the cost-effectiveness equation would require careful analysis.
Another important challenge involves addressing the fact that many manufacturers of healthcare items and equipment have widely varying recommendations for cleaning. This arises from the lack of clinically grounded standards for the testing of commonly used cleaning products and assessment of surface compatibility. Thus, manufacturer recommendations for cleaning may be driven by the minimal requirements for commercialization or financial relationship to cleaning products, which then introduce bias in recommendations. Overall, the healthcare system cannot afford the cost, training, enforcement, and lack of standardization to follow a wide range of cleaning and disinfection recommendations for various items in a room or patient care area. Approaches are needed to define a standard that either accepts the hospital-approved method for general cleaning and disinfection or definitively demonstrates incompatibility rather than compatibility with common EPA-approved products.
Another critical area for research includes the need to influence regulation as related to contact time. Currently, regulatory approval is based on efficacy of the product under conditions not reasonably found in healthcare settings. Approval of products for effectiveness under the conditions in which they are intended is needed. While the rationale of going above and beyond what is needed may be appealing, the practical applications and costs of pursuing unnecessary rigor is detrimental to the economics and efficiency of health care without gaining any benefit to patient safety.
There also is a need to develop more globally applicable research models. Since the realistic goal of environmental cleaning and disinfection of patient care areas is not to produce a continuously sterile surface environment but rather to effectively decrease pathogen transmission, multicenter studies evaluating both environmental contamination and acquisition also have the potential for identifying a threshold of environmental contamination below which transmission—and therefore disease risk—is minimized. Identifying such a threshold for key healthcare-associated pathogens could then facilitate additional studies using such a threshold as an acceptable gold standard for minimizing disease risk. Such definitions would be particularly useful as the field struggles to understand the value of very high-cost disinfection technologies. In addition, such models could also be of value given the high cost of trials, since proof of disease reduction in a timely fashion would not be feasible for each and every advancement in cleaning policy practice or disinfection science.