Two labs, two results for samples

[Ronan Kelly]

Two labs, two results for samples


Nalini RavichandranFirst Published : 02 Sep 2009 03:30:00 AM ISTLast Updated : 02 Sep 2009 06:42:45 AM IST

CHENNAI: Parents of a six-year-old boy, whose throat swab tested positive for swine flu in one laboratory and negative in another, are perplexed over the real status of the child. He has been put on Tamiflu treatment at the Institute of Child Health in Egmore.


While some doctors put to rest speculations on laboratory tests for swine flu going wrong by saying results could vary if the swabs were collected on different days, Health Secretary, V K Subburaj, said that private scan centres usually did a rapid test, which were inaccurate. He said swab testing was the most authentic in the King?s Institute. He advised that confirmatory tests should be done only at government hospitals.

Talking to Express, Vaish- ali, child?s mother, said the boy had been on antibiotic treatment for fever and when it recurred, a swine flu test was done at a private scan centre on Saturday.

Before the results came out, the child was taken to the Communicable Diseases Hospital on Sunday, when the swabs were collected and sent to the King?s Institute. While the result for the test taken by the private scans came negative, the CDH tested the boy positive for swine flu, the result of which came on Tuesday.

 

[Commonground]

Re: Two labs, two results for samples

wow.....:surrender:

 

[Ronan Kelly]

Re: Two labs, two results for samples

It seems like some are really profiting from this;

Labs increase H1N1 testing rates
Pushpa Narayan, TNN 3 September 2009, 03:20am IST

CHENNAI: With the number of patients visiting private laboratories for A (H1N1) tests increasing several fold, labs have hiked the cost of the test
by more than 60%.
?The demand for the test is high. Getting reagents for the test is becoming difficult. So we have increased the price from Rs 3,000 to Rs 5,000,? said a doctor who owns a private laboratory that has been certified by the government to conduct the test. Another laboratory charges Rs 4,000 for the same test, which is done free of cost by King Institute.

With complaints of discrepancies in results of tests conducted by government labs and private labs, the state health department has asked all private laboratories to send 10% of the number of samples that tested positive and negative.
?It?s important to standardize the test. King Institute has already been sending random samples to the National Institute of Communicable Diseases in New Delhi to reconfirm its diagnosis. It?s not possible for the Delhi institute to recheck every sample, but they do a random sampling test. We want private laboratories also to get this done. This way we can determine the testing standards,? said Director of Public Health Dr S Elango. The directorate, he added, has been receiving complaints on discrepancies in results between government and private laboratories.

The private laboratories say they do at least 20 tests on a daily basis. Several parents, particularly of students from schools where students had tested positive, rush to labs even when their child has slight cold, fever or sore throat.

Dr Elango admitted there were complaints about differences in the test but said that was because many patients conclude their results with the initial screening test. The screening test, which costs Rs 750, is done with nasal swabs. ?The test result is positive if the person infected by any of the viruses in the range of H1 to H18 or from N1 to N9. If it is positive we tell people they would have to undergo a confirmatory RT PCR test for A H1N1 virus. But many conclude that they have the disease and we are blamed for giving false positives,? he added.

The state health department it is now considering whether or not to allow laboratories to do the screening test.

?We have not fixed any ceiling for the fee they can charge, but we have urged them not to profiteer from the epidemic. People prefer the screening test as it is cheaper. But they should be aware that the test is not a gold standard and has a large percentage of error. Any confirmation should be done only with the WHO/CDC prescribed RTPCR test,? said Dr Elango.
http://timesofindia.indiatimes.com/articleshow/4966195.cms

 

[Pathfinder]

Re: Two labs, two results for samples

Most of the cases in US are not tested for H1N1 unless hospitalised but if Influenza A fast test is positive, doctors conclude that it is H1N1. I am not sure if the first post is about Influenza A fast testing or the "real" H1N1 testing . According to this link the fast flu test is not always reliable.



Rapid Swine Flu Test Misses Many Infections

Doctors should diagnose based on symptoms and strains in circulation, experts say

THURSDAY, Aug. 6 (HealthDay News) --

Doctors can't rely on rapid tests to diagnose the pandemic H1N1 swine flu, say U.S health officials who evaluated three kits and found that they miss many infections.

The tests do a better job detecting seasonal flu than H1N1 flu, the U.S. Centers for Disease Control and Prevention reported. Sensitivity for the H1N1 swine flu was just 40 to 69 percent.

"These are rapid tests that the physician would do in the office while the patient is waiting," said Michael Shaw, associate director for laboratory science in CDC's influenza division and the report's co-author. "These tests can sometimes provide misleading results."

A quick flu test is just one diagnostic tool, Shaw said. "You shouldn't rely on it alone," he said. "There is no substitute for the judgment of the clinician."

Because people might test negative but actually have the flu, Shaw said, "we want to emphasis that the clinician should also go by the patient's symptoms and what they know is circulating in the community."

Positive test results are accurate, however. "But a positive result only tells you it's flu, not what kind," Shaw said. "It could be seasonal, it could be the pandemic strain." In either case, he said, doctors could start antiviral treatment with a drug such as Tamiflu.

For people at high risk for flu complications, doctors should start treatment with antiviral medication and also get a test to confirm the results, which can take 24 hours, Shaw said.

For the report, which is published in the Aug. 7 issue of the CDC's Morbidity and Mortality Weekly Report, CDC researchers tested three commercially available rapid influenza diagnostic tests that can identify influenza A or B antigens in about 15 minutes. Respiratory samples were used from 65 people known to have swine flu or seasonal flu.

The tests were able to detect the H1N1 swine flu only when a high percentage of the virus was in the respiratory sample, which means that many infections would be missed, according to the CDC.

Shaw said that people will shed the most virus shortly after symptoms start so, for the most accurate results, it's important to give the test early.

Fast flu tests have been in use for a couple of decades. "It's not news that these tests are not as sensitive as we would like them to be," Shaw said. The question for the CDC was whether they would work with the new pandemic strain, he said.

Dr. Marc Siegel, an associate professor of medicine at New York University Langone Medical Center in New York City, said that anyone currently suffering from the flu has H1N1 swine flu.

Right now, the test is not clinically important, Siegel said. "If you got flu now, this is what you got," he said.

Siegel agrees with the CDC that a flu diagnosis is best made on the basis of a person's symptoms and the flu strains in circulation.

"I make the diagnosis on clinical grounds. I am comfortable doing that," Siegel said. "The test is just an adjunct. It's helpful if it's positive, but a negative flu test does not rule it out. Go by your clinical judgment."

Getting a more definitive test, Siegel said, would have two benefits: It could identify what viruses are circulating, and it could confirm a diagnosis for high-risk patients susceptible to complications such as pneumonia.


http://www.nlm.nih.gov/medlineplus/news/fullstory_87834.html