本帖最后由 StephenW 于 2012-8-1 12:03 编辑
HBV Journal Review
August 1, 2012, Vol 9, no 8
by Christine M. Kukka Few Restrictions Recommended for HBV-Infected Doctors and Medical Students
Few if any restrictions should be imposed on physicians, dentists and medical students who are infected with the hepatitis B virus (HBV), according to new guidelines published by the U.S. Centers for Disease Control and Prevention (CDC) in the July 6, 2012 issue of the Morbidity and Mortality Weekly Report.
The report was issued after some hospitals imposed widely varying restrictions on HBV-infected physicians, and medical schools also arbitrarily forced infected medical students to curtail their studies or choose other fields. Today, an estimated 25% of medical and dental students are descended from families who came from Asia, Africa and the Middle East, where HBV rates are high.
The CDC conducted an exhaustive study into provider-to-patient transmission of HBV infections and that found that widespread hepatitis B immunizations have reduced new infections in the U.S. by 85% in the past 20 years. They identified only one case of provider-to-patient transmission of HBV since 1994, and only one case of a dentist-to-patient infection since 1991.
Investigators also looked at the frequency of patient-to-doctor transmission of hepatitis B and found that occupational exposure among health care providers declined from 10,000 cases in 1983 (before universal immunization began) to 100 cases in 2009.
The combination of hepatitis B vaccinations and antiviral medications that can reduce a doctor's viral load (the amount of HBV DNA circulating in the blood) has dramatically cut down the risk of HBV transmissions, officials noted.
CDC officials recommend:
- Infected Health care providers' HBV DNA levels should be monitored.
- If a surgeon performs procedures where needlestick injuries are likely to occur (typically in closed openings where visibility is poor), the doctor should maintain a viral load under 1,000 international units per milliliter, with semi-annual review of his/her HBV DNA.
- Expert panels may monitor such cases without ever knowing the identity of the surgeon or medical student's identity in order to protect their confidentiality.
- Such panel oversight is not needed unless providers perform high-risk surgery. Infected providers who do not perform high-risk procedures should not be subject to any restrictions.
- Hospitals, medical and dental schools should have written policies and procedures for identification and management of HBV-infected providers, students and school applicants.
Hepatitis B Continues to Be Under-Diagnosed and Under-Treated in the U.S.
Only 50,000 of an estimated 2 million people infected with HBV in the U.S. are receiving antiviral treatment–an example of the lack of screening and treatment that the vast majority of hepatitis B patients receive, according to a report published in the journal Hepatology.
Why do so few people living with HBV receive adequate screening and treatment? Officials cite poor access to medical, ignorance of their infection, lack of health insurance, and failure on the part of health care providers to identify and screen those at high risk of infection.
Among those at highest risk are Asian-Americans, of whom one in 10 are chronically infected. Two-thirds of immigrants from countries with high prevalence of HBV infection, including Asia, Africa, and the Middle East, do not know they are infected.
Other at-risk populations include men who have sex with men and intravenous drug users. While some of these people have access to health care, they also are often not screened for the infection by their providers.
Mistrust of Western health care, denial, and other cultural barriers prevent many people from being screened, which is why it is important for primary care providers to educate, screen, vaccinate, and treat patients.
Among gay men, providers either don't know their sexual orientation or they fail to educate patients about their risk of HBV and screen and vaccinate them.
"Many clinicians feel they only need to screen those with abnormal liver tests, ... or when they present with symptoms," experts wrote.
Despite the availability of new, effective antivirals, "recent interviews with physicians who treat (Asian-American) patients ... show that close to 60% of these physicians are not aware of current treatments," they added, given that only 4% to 5% of HBV patients are screened or treated.
Clearly hepatitis B is under-diagnosed and under-treated, experts assert. "The more difficult task will be how to mobilize stronger and more persistent patient, physician, and community advocacy to increase the number of patients screen, diagnosed, and treated."
Only 6% of Patients at Risk of Liver Cancer Are Properly Screened in the U.S.
Most patients at high risk for liver cancer–including those infected with cirrhosis and HBV–are not getting adequate liver cancer screening, according to a study published in the Journal of General Internal Medicine.
Investigators found only 6% of patients at risk receive screening as recommended by national guidelines. About 20% receive inconsistent monitoring and the remaining patients are not monitored at all. Most of them are non-white and low-income.
“We found multiple points in the process of care where the system is failing," the lead author said. The most common reason for lack of monitoring is that doctors fail to order adequate tests in patients with cirrhosis. One study of 270 American patients found that the 3-year survival for liver cancer was 12% among cirrhotics who had received no monitoring.
Despite the benefits of monitoring, surveillance remains problematic across the U.S., even in Veterans Affairs hospitals, where an extensive system for surveillance is in place, the rates are between 60% and 70%.
Monitoring for liver cancer was so inconsistent that nearly 40% of patients were not recognized as having liver disease and/or cirrhosis prior to being diagnosed with liver cancer. Even when cirrhosis was identified, only 38% of diagnosed cirrhotics received orders for additional surveillance. The fault lay both with providers who did not order the tests, and patients who did not return for follow-up testing.
The study showed that individuals who drank alcohol on a daily basis were the least likely to receive surveillance from their doctors–and not due to patient failure to return for tests.
Patients lucky enough to receive care from a hepatologist–a liver specialist–had the highest rates of adequate follow-up tests. Their surveillance rates were 51.7% compared to primary care patients who had a low 16.9% surveillance rate.
The majority of patients with cirrhosis in the United States are cared for by primary care doctors not hepatologists. Experts suggested that perhaps hepatologists need to educate primary care providers about how to properly care for cirrhotic patients.
Treatment with Potent Antivirals Prolongs Life and Is Cost-Effective
Dutch researchers analyzed the cost-effectiveness of treating chronic hepatitis B patients in a middle-income country with moderate HBV prevalence and found that treating patients with liver damage with one of the newer antivirals, such as entecavir (Baraclude) or tenofovir (Viread) made financial sense.
About 3.2 million people in The Netherlands have chronic hepatitis B and an estimated 25% are eligible for treatment. If left untreated, about 31% will die from liver-related complications. Over a 20-year period:
- 11 % will develop cirrhosis
- 12 % will develop liver cancer
- And 6 % will require liver transplantation.
Experts estimate that quality adjusted life years (QALYs) for the no-treatment scenario ranges from 9.3 to 14 years. But if either entecavir or tenofovir is used for those requiring treatment, their QALYs increases great to between 16.6 to 19 years.
"In a country with considerable amount of active chronic hepatitis B patients, (treatment) with a highly effective drug has the most health-gain, and is cost-effective in both HBeAg-positive and negative in all stages of liver disease," experts wrote in the July issue of the European Journal of Health Economics.
U.S. Patients Follow Doctors’ Order and Take Antivirals as Prescribed
How many U.S. hepatitis B patients follow their doctors’ orders and take a daily antiviral pill as prescribed? Nearly all, according to a study published in the July issue of the Journal of Medical Economics.
Researchers followed 825 patients who were prescribed either entecavir or tenofovir (the “first-line” antivirals currently recommended by medical guidelines) and 916 other patients who were prescribed other antivirals, including lamivudine (HBV-Epivir), adefovir (Hepsera), or telbivudine (Tyzeka).
Those taking entecavir or tenofovir were twice as likely as to take their meds regularly, compared to the other group, and the entecavir-tenofovir group had fewer hospitalizations during treatment.
The increased adherence may result from the higher medical costs associated with entecavir and tenofovir ($1214 and $1332 per patient per month, respectively) or lower drug resistance, compared to the less desirable antivirals.
However, both groups were very conscientious about taking their medications, and researchers point out there is a definite cost-benefit in treating patients with antivirals, given their limited side effects which could have chipped away at adherence.
Experts Suggest "Healthy" ALT Levels Should Be Lowered to 17 and 21 IU/L
Taiwanese researchers evaluated two groups of 21,282 and 13,064 healthy people and determined that healthy levels for alanine aminotransferase (ALT)–which rise when liver cells are damaged–should be lowered to 21 international units per liter (IU/L) in men and 17 IU/L in women.
Researchers have been ratcheting down what they consider to be the upper reaches of "healthy" ALT levels in recent years. ALT is released into the blood stream when the liver is damaged. Several years ago, the "healthy" rates were dramatically reduced from around 50 IU/L for both men and women to 30 IU/L for men and 19 IU/L for women. Now experts are recommending another reduction.
Some experts suggest that "healthy" ALT levels may vary by ethnicity and body mass–Asians tend to have lower "healthy" ALT levels than do their heavier European and American counterparts.
According to this recent study published in the July issue of the Journal of Alimentary Pharmacology and Therapeutics, 95% of the healthy people they sampled in the massive screening had 21 IU/L and 17 IU/L for men and women respectively.
Determining what healthy ALT levels really are is important because treatment for hepatitis B is often initiated when ALT levels rise above healthy levels.
Maize Seeds May Be Affordable Source of Hepatitis B Vaccine
Researchers continue to search for more cost-effective ways to create large supplies of the hepatitis B vaccine, which would result in more people being immunized at lower costs. Currently, hepatitis B vaccines must be refrigerated and three doses are required, which makes it difficult to immunize children and adults in remote areas.
Recently, progress has been made to grow the hepatitis B surface antigen (HBsAg) in maize (corn). Only HBsAg is used in the vaccine, to trigger production of protective surface antibodies.
A team of U.S. researchers, reporting in the July issue of the Plant Biotechnology Journal, say they are close to developing the antigen in maize seeds, which can withstand heat and be administered orally, instead of through an injection.
"Optimal heat stability was achieved after oil extraction of ground maize (seeds), either by supercritical fluid extraction or hexane treatment," experts wrote.
The HBsAg vaccine material in the maize could withstand heat reaching up to 55 degrees F and the maize seed contained high concentrations of the antigen.
Chickweed May Be an Effective Antiviral Against Hepatitis B
Stellaria media villars, also known as chickweed, is a traditional Chinese medicine that has been used for more than 200 years to treat dermatitis and other skin diseases. Researchers used chickweed juice as an antiviral agent against HBsAg and HBeAg in laboratory cultures.
They found the chickweed juice, "…effectively suppressed the secretion of HBsAg and HBeAg with inhibition rates of 27.92% and 25.35% after 6 days of treatment, respectively." It also reduced HBV DNA (viral load).
Writing in the journal Molecules, researchers wrote, "our results demonstrate that (chickweed) possesses potential anti-HBV activity," and may be a potential effective antiviral against hepatitis B.
Hepatitis B Does Not Impact Quality of Life until Severe Cirrhosis or Liver Cancer Occur
How much does a chronic hepatitis B infection impact quality of life? Canadian health officials surveyed 433 hepatitis B patients over a two-year period and found there was little impact until patients developed severe liver disease.
According to their report in the July issue of the Canadian Journal of Gastroenterology, researchers studied 294 without cirrhosis, 86 with cirrhosis, 23 with liver cancer, and 30 who had received liver transplants.
Quality-of-life scores in noncirrhotic patients were similar to those of healthy people. The scores of patients with milder cirrhosis were not significantly lower; however, patients with decompensated cirrhosis and liver cancer had significantly lower quality of life scores compared with noncirrhotic patients. Use of antiviral medications did not appear to impact quality of life.
Another Study Shows Interferon Effective in Patients with HBV Genotype B
Another study, this one involving 65 HBV genotype B and C patients, shows that pegylated interferon is most effective in patients with HBV genotype B.
According to a study published in Hepatitis Monthly, the patients were treated for 48 weeks with a once weekly injected of pegylated interferon, and then followed for another 24 weeks.
They reported that 66.7% of genotype B patients responded to the treatment with sustained low viral load and normal ALT levels, while only 26.3% of genotype C patients responded.
New Study Confirms the Safety of Antiviral Treatment in Pregnant Women
Columbia University Medical Center researchers looked at pregnancies between 1989 and 2011 where women were treated with antivirals to prevent either HBV or HIV infection of their infants to see if antiviral treatment increased birth defects.
According to their report in the July issue of the Journal of Hepatology, they analyzed data from the Antiretroviral Pregnancy Registry (APR), the largest safety database tracking these pregnancies. In 200 women, either lamivudine or tenofovir were used to prevent mother-to-child HBV transmission.
Of 13,711 HIV and HBV combined cases analyzed, the overall birth defect prevalence was the same as in the general population.
Vitamin B12 Helps Hepatitis C Patients Treated with Interferon and Antiviral
In a finding that may benefit hepatitis B patients, scientists have found that vitamin B12 supplements significantly improve the effectiveness of pegylated interferon and ribavirin treatment in patients infected with the hepatitis C virus (HCV), according to a study published online July 17 in Gut.
Researchers treated two groups of hepatitis C patients, who had never been treated before, with interferon (similar to what is used in HBV-infected patients) and the antiviral and added B12 to one group’s treatment regimen.
The vitamin-treated group responded more favorably to treatment–and they responded earlier. Even patients with difficult-to-treat HCV genotypes had higher response rates to treatment when B12 was added.
"In conclusion, vitamin B12 supplementation significantly improves the rates of sustained viral response in HCV-infected patients naive to antiviral therapy, particularly those infected with genotype 1 and a high baseline viral load," the authors wrote.
Vitamin E May Decrease Liver Cancer Risk
Chinese patients (including healthy individuals and those with hepatitis B) who take vitamin E have half the rate of liver cancer than those who did not receive the supplement, according to a report in the Journal of the National Cancer Institute.
Researchers scoured data on 132,837 patients in a Shanghai health study and evaluated their vitamin intake from meals and supplements. Over the course of the study follow-up, 267 patients developed liver cancer over 10.9 years for women and 5.5 years for men. They found taking vitamin E supplements nearly halved the risk of liver cancer compared to those who did not take the supplements. Women appeared to benefit more from vitamin E, but it benefited both genders.
The vitamin could offer protection by inhibiting activation of carcinogens, boosting the immune system, or preventing DNA damage and enhancing DNA repair.
When they examined other vitamin intake, researchers found that vitamin C appeared to increase the risk of liver cancer as did multivitamins among men.
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发表于 2012-8-1 11:58
