Inconvenient study: Hand washing up, rates unfazed
Researcher says findings being misinterpreted
Surprising research results — which have been widely misinterpreted as evidence that hand hygiene has little impact on infection rates — more likely reveal that health care infections (HAIs) arise from complex causes and cannot be prevented by a single intervention, the author tells Hospital Infection Control.
"The study is something of a cautionary tale, but it certainly shouldn't be interpreted as hand hygiene is not important," says Mark Rupp, MD, director of infection control at the University of Nebraska Medical Center in Lincoln. "I've seen some of headlines saying: 'Study shows hand hygiene doesn't work.' That's really not what the study says. These infections have more than one aspect of pathogenesis. Hand hygiene [alone] will not make low infection rates go away."
But perception may be every bit as important as reality in an age when infection prevention is increasingly the subject of consumer activism, press coverage, and state and federal legislation. Infection control professionals can ill afford to see hand hygiene — the cardinal principle of HAI prevention — sent out to pasture with sacred cows of the past. "There is no doubt that you can pick up pathogens on your hands and carry them from person to person," Rupp emphasizes. "We need to make sure that is one way that transmission of infections does not occur."
That said, hand hygiene in and of itself may not be enough, though the conclusion complicates a message ICPs and major medical groups have been trying to convey for years. "There is perception out there if these nurses and doctors would just clean their hands, all of our infection control problems would go away," Rupp says. "These are complex infections. I think it is a little naive to suggest one intervention is going to make a big difference. Hand hygiene is an important aspect of the overall infection control program, but it is not the end-all, be-all of infection control."
The key is combining a high adherence to hand hygiene with "bundle" approaches featuring several interventions simultaneously, including environmental cleaning and prudent use of antibiotics. "All of those things have to be in the mix," he says. Still, Rupp emphasizes that many other infection control prevention policies were already in place in his hospital, which had low infection rates at baseline. "I think our low infection rates would indicate that our practices were pretty good," he says. "It is important for people to understand that you can't take a single measure and expect to have a huge impact on [infections.] It is a little bit disappointing, but the study speaks for itself."
Crossover study in two ICUs
Rupp and colleagues found that the introduction of alcohol-based gels resulted in a significant and sustained improvement in the rate of hand hygiene adherence, but the overall infection rates were unaffected. The study was conducted in two medical/surgical ICUs for adults, each with 12 beds, from August 2001 to September 2003.1 An alcohol-based hand gel was provided in one critical care unit and not provided in the other. After one year, the assignment was reversed. The hand hygiene adherence rate and the incidence of nosocomial infection were monitored. Hand culture samples also were obtained from nurses' hands. Of note, fingernail length greater than 2 mm, wearing rings, and lack of access to hand gel were associated with increased microbial carriage on the hands. During 17,994 minutes of observation, which included 3,678 opportunities for hand hygiene, adherence rates improved dramatically after the introduction of hand gel, increasing from 37% to 68% in one unit and from 38% to 69% in the other unit, the authors reported.
Improvement was observed among all groups of health care workers, but the resonating "sound bite" from the research finding is based on a disturbing finding reported by the authors: "No substantial change in the rates of device-associated infection, infection due to multidrug-resistant pathogens, or infection due to Clostridium difficile was observed."1 Of course, it is widely known that spore-formers like C. diff can be difficult to remove with alcohol rubs, but that doesn't tell the whole story. "We looked at ventilator-associated pneumonia, catheter-related bloodstream infections, catheter-associated urinary tract infections, rates of infection with MDROs," Rupp says. "We saw a big upswing in hand hygiene [compliance], but we didn't see a corresponding decrease in infection rates."
One possible explanation is that the study was underpowered and ultimately unable to detect small changes in infection rates that were low at baseline, he notes. The researchers ran the study out over two years in hopes of achieving statistically significant rate changes, but it was not to be. Rupp hypothesized that he would at least find infection rate decreases that fell short of statistical significance. "We really just didn't see any trends in infection rates," he says. "That's disappointing and quite frankly, somewhat surprising."
The rate of hand hygiene compliance achieved may not have been enough, though 70% sounds impressive compared to the historical estimates that only about half of health care workers disinfect their hands prior to a typical patient encounter. "You may have to push up hand hygiene compliance above a certain threshold that we don't know right now," he says. "It might have to be 90% or closer to 100% before hand hygiene really does start to make a big difference."
Moreover, many variables affect transmission at any given care moment, including the amount of inoculum on the worker's hands, the virulence of the organism, and the status of the patient's immune system. Environmental and process factors such as room cleaning and removing catheters promptly also play a role in the origin of infections, some of which may not be preventable under in any scenario.
"Another misnomer that people are [hearing] is that all nosocomial infections are preventable," Rupp says. "I do think we can prevent a lot of infections. We can drive these things pretty low, but we are not going to make them all go away."
- Rupp ME, Fitzgerald T, Puumala S, et al. Prospective, controlled, crossover trial of alcohol-based hand gel in critical care units. Infect Control Hosp Epidemiol 2008; 29:8-15.