Press releases Monday 21 September to Friday 25 September 2009

Please remember to credit the BMJ as source when publicising an article and to tell your readers that they can read its full text on the journal's website (http://www.bmj.com).

(1) Hygiene and physical barriers should be given higher priority in pandemic plans
(1) Not enough evidence to support routine prostate cancer screening
(3) Taking antidepressants in early pregnancy linked to child heart defects

(1) Hygiene and physical barriers should be given higher priority in pandemic plans
(Research: Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review)
http://www.bmj.com/cgi/doi/10.1136/bmj.b3675

Hygiene and physical measures, such as handwashing, wearing masks and isolating potentially infected patients, are highly effective in preventing the spread of viral infections (including influenza) and should be given higher priority in national pandemic preparation plans, argue researchers in a study published on bmj.com today.

In 2007, Professor Tom Jefferson and colleagues showed that physical interventions, such as handwashing and wearing masks, gloves and gowns are highly effective in preventing the spread of respiratory viruses. However, the current mainstay of pandemic interventions still seems to rest on vaccines and antiviral drugs with little evidence supporting their widespread use, especially against a seemingly mild threat like the new H1N1 (swine flu) virus.

So the team set out to update their 2007 review by analysing the results of 59 published studies on the effectiveness of physical measures to interrupt or reduce the spread of respiratory viruses such as influenza and SARS.

They included any intervention to prevent viral animal-to-human or human-to-human transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection and hygiene) compared with do-nothing or with another intervention. They excluded vaccines and antiviral drugs.

Differences in study design and quality were taken into account to minimise bias.

The results show that regular handwashing (more than 10 times a day) and wearing masks, gloves and gowns were effective individually against all forms of acute infectious respiratory disease, and were even more effective when combined (only three patients would need to be treated in this way to prevent one case of respiratory disease).

The highest quality trials suggested that spread of respiratory viruses can best be prevented by hygienic measures in younger children and within households.

The team found limited evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks and they can also cause skin irritation. However, the effect of adding antiseptics to normal handwashing to reduce respiratory disease remains uncertain.

Global measures, such as screening at entry ports were not properly evaluated, and there was limited evidence that social distancing was effective.

Many simple and low cost measures can be highly effective at reducing transmission of epidemic respiratory viruses, especially when they are part of a structured programme including education, and when they are delivered together, say the authors.

They call for nationwide handwashing programmes and personal hygiene teaching in schools.

In situations of high risk of transmission, barrier measures such as gloves, gowns, and masks with filtration apparatus and isolation of likely cases should also be implemented.

Society should invest more resources into studying which physical interventions are the most effective, ways to facilitate their introduction, and flexible and cost-effective means of minimising the impact of acute respiratory infections, they conclude.

Contact:
Dr Tom Jefferson, Cochrane Acute Respiratory Infections Group, Roma, Italy
Email: jefferson.tom@gmail.com

(2) Not enough evidence to support routine prostate cancer screening
(Research: Prostate specific antigen for early detection of prostate cancer: longitudinal study)
http://www.bmj.com/cgi/doi/10.1136/bmj.b3537
(Analysis: Screening for prostate cancer remains controversial)
http://www.bmj.com/cgi/doi/10.1136/bmj.b3601
(Editorial: Prostate specific antigen for detecting early prostate cancer)
http://www.bmj.com/cgi/doi/10.1136/bmj.b3572

There is insufficient evidence to support population-wide screening for prostate cancer using the prostate specific antigen (PSA) test, conclude two papers published on bmj.com today.

The authors say that the PSA test cannot distinguish between lethal and harmless prostate cancer, leading to overdiagnosis and overtreatment of healthy men.

Prostate specific antigen (PSA) is a protein produced in the cells of the prostate gland. It is present in small quantities in the blood of healthy men, and is often elevated in men with prostate cancer and in men with benign prostatic enlargement.

PSA screening is widely used in many countries, but it remains controversial. A recent study showed that prostate cancer deaths were lower among screened men but at a cost of considerable overdiagnosis and treatment.

So in the first study, a Swedish team of researchers set out to assess how well prostate specific antigen predicted a future prostate cancer diagnosis.

Using PSA test results from 540 men diagnosed with prostate cancer measured several years before diagnosis and from 1,034 healthy controls, they found that the PSA test did not attain the likelihood ratios (a measure used to predict disease) required for a screening test. Only very low concentrations of PSA, less than 1ng/ml, virtually ruled out a diagnosis of prostate cancer during follow-up.

The authors conclude that additional biomarkers for early detection of prostate cancer are needed before population based screening for prostate cancer should be introduced.

In a second analysis paper, US researchers reviewed the benefits and harms of PSA screening and conclude that data on costs and benefits remain insufficient to support population based screening. They also say that the financial and psychological costs of false positive results, overdiagnosis and overtreatment of prostate cancer need to be measured more precisely.

Finally, they believe that men should be fully informed of the benefits, risks and uncertainty associated with the PSA test before they are screened.

This view is supported in an accompanying editorial by researchers at Monash University in Australia.

Clinicians and patients are faced with many uncertainties when considering whether or not to undergo prostate screening, write Dr Dragan Ilic and Professor Sally Green.

Further research is required to develop and evaluate a valid screening test for prostate cancer, they say. Until such a test is available, a shared decision making approach to undertaking screening should be adopted.

Contacts:
Research: Mattias Johansson, Postdoctoral Fellow, Genetic Epidemiology Group, International Agency for Research on Cancer (IARC), Lyon, France
Email: JohanssonM@fellows.iarc.fr
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