The review, which appears in the current issue of The Cochrane Library, asserts that while the risk of HIV being transmitted through a contaminated needle is low for doctors, nurses and other health care workers – a 1-in-333 risk according to the Centers for Disease Control and Prevention (CDC) – such a risk is “hardly insignificant.”
Many countries recommend post-exposure prophylaxis, or PEP – in which doctors try to kill the virus in the body before it takes hold – if a health care worker has been potentially exposed to HIV, typically through a needle stick since the virus that causes AIDS is transmitted through blood. The same approach is used to treat people who have been exposed potentially to HIV through sex.
Reviewers, however, stated that there's been little research into PEP, and it's not clear what should be done when health care workers are exposed to patients who are resilient to some drugs.
Difficult to Find Study Participants
Review co-author George Rutherford, M.D., of the University of California, San Francisco's Institute for Global Health, said that the low number of actual cases of infection makes it difficult for researchers to find enough people to study the effectiveness of post-exposure treatment. He added that, not surprisingly, exposed health care workers haven't been willing to take part in any study that might result in their taking a placebo instead of drug treatment.
The researchers were only able to find a single study that compared those who took drugs after exposure to those who didn't. That study, of 712 exposed health care workers, found that the odds of becoming infected with HIV were reduced by about 81 percent among those who took zidovudine — an anti-HIV drug also known as AZT or Retrovir — after exposure.
The study also reported that the odds of HIV infection were higher if a health care worker had a deep injury, if there was visible blood on the device (such as a needle), if the needle had been placed in the infected patient's blood vessel or if the patient was terminally ill. A deep injury appeared to be by far the most dangerous of the factors.
HIV patients typically take more than one drug, and doctors prescribe multiple drugs as prophylaxis for exposed health care workers as well. While there's no research suggesting whether that's a good idea in the latter case, the reviewers still recommend a multiple-drug regimen because it works in HIV-infected patients.
Questions remain, however, about what to do if an HIV patient is resistant to existing medications. “That is," Rutherford asked, "what do you do if you know a patient is not susceptible to the first-line drugs?”
There’s also the matter of side effects, which can keep people from wanting to continue on HIV drugs for the recommended full month.
For now, Rutherford recommends that health care workers follow federal guidelines regarding the risk of HIV infection from needle sticks.
Risk Of Infection Always Looming
Still, the risk of an infection seems likely to never go away. An estimated 26 percent of nurses surveyed reported having been injured once in their careers by a needle contaminated with a patient's blood, while 14 percent reported having been injured at least twice, according to Frank Myers, director of clinical epidemiology and safety systems at Scripps Mercy Hospital in San Diego.
However, out of all the nurses surveyed, 56 percent reported no such injuries, said Myers, whose study will be published in the journal Nursing 2007.
On the positive side, hospitals are worrying more about the potential risks to health care workers and companies are developing safer medical devices, such as syringes that retract needles when they're removed from patients.
"The more years of experience, the more likely you are to have had such an injury, driven in part by both the years at risk and the earlier years of having fewer safety devices and a poorer safety environment," Meyers said.