Why Wash?

In 2005, Boston-based doctors published the very first clinical trial of alcohol-based hand sanitizers in homes and enrolled about 300 families with young children in day care. For five months, half the families got free hand sanitizer and a “vigorous hand-hygiene” curriculum. But the spread of respiratory infections in homes didn’t budge, a result that “somewhat surprised” the researchers. A Columbia University study also found no reduction in common infections among inner-city families given free antibacterial hand soap, detergent, and cleaning supplies. The same year, University of Michigan epidemiologist Allison Aiello summarized data on hand hygiene for the FDA and pointed out that three out of four studies showed that alcohol-based hand sanitizers didn’t prevent respiratory infections. Then, in 2008, the Boston group repeated the study—this time in elementary schools—and threw in free Clorox disinfecting wipes for classrooms. Again, the rate of respiratory infections remained unchanged, though the rate of gastrointestinal infections, which are less common than respiratory infections, did fall slightly. Finally, last October, a report ordered by the Public Health Agency of Canada concluded that there is no good evidence that vigorous hand hygiene practices prevent flu transmission. …

In hospitals, outside of these clinical trials, just half of doctors and nurses regularly clean their hands before patient care, despite widespread publicity. More worrisome: In hospitals where massive educational efforts have increased hand-washing rates from 40 percent up to 70 percent, there has been no overall reduction in infection rates. Even in highly regulated places like hospitals, the promising benefits of hand-washing remain largely unrealized.

More here; HT Tyler.

Added 12Mar: Yvian lists may pro-washing studies here.

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  • Hm, I’m going to go out on a limb here and guess that your hypothesis for reason behind the pro-sanitizing campaigns has something to do with status and signaling, and little to do with actual medical outcomes.

  • Robert Speirs

    It couldn’t be that our efforts aren’t necessary, we just must not be spending enough time and money on browbeating people. Yeh, that’s the problem! But, then, that’s always the problem, right?

  • Ed

    Bizarre! Is it that hand washing is a case of increasing returns, and benefits don’t kick in until above 70%? After all if there’s one dude going around and pawing everyone that could cancel out 50 other people’s efforts. And if hands really aren’t the issue, any word on where infections picked up in hospitals do come from?

    Also a policy that treats doctors like fifth graders and makes sure they’ve scrubbed behind the ears doesn’t sound status- or signalling-driven.

  • In this OB post egregiously entitled “Doctors Kill“, you recounted this anecdote:

    A colleague of my wife was a nurse at a local hospital, and was assigned to see if doctors were washing their hands enough. She identified and reported the worst offender, whose patients were suffering as a result. That doctor had her fired; he still works there not washing his hands. Presumably other nurses assigned afterward learned their lesson.

    At the time, I informed you (as one with expertise about how hospital administrations work, as well as about nosocomial infections) that neither the notion of the doctor having the nurse fired, your wife’s knowledge of whether the doctor still worked there and still was not washing his hands, the likelihood that any such study actually occurred (how would it be conducted?) nor any documentation that the doctor was responsible through negligent hand-washing for the demise of his patients was likely to be true. We had some back and forth both on my blog and on OB, as well as by private email, the result being that you told me if I mentioned the incident again, the comments would be erased. Now you’re quoting your own source saying that “In hospitals where massive educational efforts have increased hand-washing rates from 40 percent up to 70 percent, there has been no overall reduction in infection rates.”

    Short memory, or just riding both sides of the fence?

  • Maybe the hand sanitizers are made with the same innocuous stuff they put in women’s anti-wrinkle creams. Perhaps there is a “tipping point” that needs to be reached before the sanitizers become effective. If so, you would need to find a way to overcome the free-rider problem.

    If half the the families used the sanitizer and the kids mixed together at day care, should they have been surprized when there wasn’t much affect?

  • Yvain

    I take your single gated inaccessible study saying handwashing in hospitals doesn’t help, and raise you seven studies (technically fifty if you count the ones in meta-analyses) saying it does:

    Victorian handwashing program at six hospitals associated with major reduction in MRSA infection

    Electronic handwashing monitoring decreases hospital transmitted infections 20-50%

    Handwashing training cut hospital-transmitted infection 40% over 2 years in Argentina

    Handwashing training cut neonatal hospital transmitted infections by about a third in Taiwan (http://www.ncbi.nlm.nih.gov/pubmed/15484798

    Handwashing program at University of Liege cut MRSA cases by 1/3.

    Meta-analysis of 14 studies finds that RCTs about promoting hand hygiene cut diarrhea about 30%

    Meta-analysis of 30 studies finds that hand hygiene cuts GI illness by 30% and resp illness 20%

    For good measure, here are some studies that show it has an effect in schools and homes:

    Children in Pakistani households that got handwashing councilling in an RCT got half as much pneumonia and diarrhea as the controls (http://www.ncbi.nlm.nih.gov/pubmed/16023513)

    Mandatory handwashing in elementary schools decreases absences due to illness

    Handwashing program in Chinese schools halved absences compared to control schools

    Home handwashing program cut GI illnesses by half.

    If only there was some sort of scientific community or something, that could evaluate all of these studies and make recommendations about them…

    “It is well-documented that one of the most important measures for preventing the spread of pathogens is effective hand washing.” – Center for Disease Control

    “Hand hygiene…is the single most important measure to reduce transmission of microorganisms from one person to another or one site to another on the same patient.” – UpToDate, a medical research aggregator site used by doctors

    I’m willing to accept that the Public Health Agency’s belief that hand-washing isn’t useful against influenza may be well founded (though many studies show otherwise; see for example http://www.ncbi.nlm.nih.gov/pubmed/19773323). I’m not willing to accept that one or two inaccessible very specific studies turn the balance of evidence against all those nice well-respected meta-analyses of RCTs toward anything that can be summarized as “Why Wash?”

    • I certainly don’t mean to suggest that the answer is clear on this topic. Yes, these are also quite relevant data.

      • I think this is the part where you cry uncle.

      • Robin, I appreciate the points you made in Against Disclaimers, but you are shooting yourself in the foot with posts like this. Would it really have been too difficult to say “I think this is interesting food for thought, that said, other studies have found benefits to hand washing/sanitizing.”?

  • sk

    may be the experiments should be repeated in hospitals.

  • Robert Koslover

    Does the provision of free hand sanitizers and free antiseptic wipes automatically result in their regular, consistent, and adequate use? I suspect not. After all, I had occasion to visit a patient in a well-respected hospital not along ago, for a few days in a row. Hand sanitizers were strategically positioned in hallways and on walls outside patient rooms. I used them fairly often (though I can’t claim to have been 100% consistent in that regard), but I noticed most people simply walked right past them.

    • Tim Canon

      This was the thought that popped into my mind when I read about this study elsewhere (though for the life of me I can’t remember where…probably MR). They placed sanitizers in classrooms to be used…they don’t specifically mention whether usage of hand-sanitizer rose during the time period studied.

      An anecdotal remark: At my school, the health center “strategically” placed sanitizer in quite a few spots around campus once this swine flu business hit Drudge Report and everyone started caring. I notice, and I suspect this to be this case most everywhere, that the only people I knew personally who actually used the stuff actually had their own sanitizer beforehand, and used it obsessively anyway. Of course, that doesn’t mean that my observations equal the overall trend, but if what I observed is roughly true, then the only effect of giving out free sanitizer has less to do with improved health than improved pocketbooks for those who would otherwise be using their own sanitizer and now get it for free.

  • But: “A controlled study of 200 workers at FedEx in 2004 showed that placing hand sanitizer dispensers in an office and educating workers about their use resulted in a 21% reduction in absenteeism.[28] Controlled studies showed an even greater reduction in absenteeism (51%) in elementary schools[29] and college dormitories (43%).[30]”


  • Noumenon

    the spread of respiratory infections in homes didn’t budge

    common infections among inner-city families

    out of four studies showed that alcohol-based hand sanitizers didn’t prevent respiratory infections.

    Again, the rate of respiratory infections remained unchanged,

    there is no good evidence that vigorous hand hygiene practices prevent flu transmission. …

    no overall reduction in infection rates.

    I was planning to say “so this just shows it doesn’t work against respiratory infections,” but I guess only 4 of 6 say that. And I realized colds are respiratory infections, and I did expect handwashing to help against them.

  • Anon

    Did the investigators assess compliance? If not, forget the study. Did they empirically measure compliance? For example, if given volume is expelled by the pump at each usage, what was the relationship between the volume used and expected use? This requires estimating the number of times the subjects should be washing our hands per day, such as before eating, after bodily functions, after changing the baby, before preparing food and so on and then comparing that to the volume of gel or number of wipes used. I’m betting they assessed compliance by the same questionnaire in which they asked about health events. If they did measure compliance, did they examine the relationship between compliance and the outcome variable?

  • Even in highly regulated places like hospitals, the promising benefits of hand-washing remain largely unrealized.

    What an odd conclusion! Every sentence before that led me to expect “Thus, hand-washing campaigns unlikely to be effective in reducing infection rates.”