As happy as Larry..

..in Spokane

Dollar Dazzler

Porter Hospital Laboratory has just announced a big price reduction for doing a QFT

$125.00 (Was $225.00)

and they are doing it faster

5 Days (Was 10 days)

The reason for this reduced price?

we now offer this test through Mayo Medical Laboratory (type in test number 83896).

(hat tip drrc)

Trees, woods and Forest

Here is me thinking that the 2010 Broker presentation was all about financials - well, it mostly was - but by me thinking so the big ticket item escaped my attention, again.

Except that forest saw it.

It is worth looking back at what Dick Menzies had to say about the first Diel paper

The results of Diel and colleagues are very promising, as they suggest the potential for IGRAs to enable programs to target the highest-risk patients for latent TB treatment. These findings do not call, they shout, for further prospective studies to better define the ability of IGRAs, relative to the TST, to predict future risk of active TB.

Well 2 years later there is now something to really shout about

Presented at the British Thoracic Society’s London meeting in November, this exciting study compared QFT and the TST progression rates to active TB in contact screening. The data show QFT to have 100% negative predictive value because none who tested QFT-negative (or QFT-negative/TST-positive) progressed to active TB (n = 835). The key finding is that QFT is highly predictive of active TB; a sixth of “QFT Positive” contacts, left untreated, progress to active TB within 2 years, a rate which compares favorably with that observed with TST (1 in 50–100 cases).

Short course therapy

Now published in the Respiratory Medicine Journal, the Kang study into short course therapy.

This is important as it demonstrates that QuantiFERON can track the efficacy of TB therapy when Rifampicin is used.

If Rifampicin is used in a short course therapy you have several potential benefits;

• short course is preferred over longer course
• Rifampicin is less toxic than INH
• Quantiferon can be used to check that TB infection has been cleared

There is evidence that 3 months therapy with rifampin plus isoniazid appears to be as effective as therapy with isoniazid for 6-12 months.

There is also a trial underway testing rifapentine with INH

The implication, according to Horsburgh's team, is that shorter courses of therapy would encourage more patients to comply. They point out, though, that the effectiveness of the four-month rifampin therapy has not yet been tested in large clinical trials.

An ongoing clinical trial is testing the effectiveness of a three-month course of isoniazid plus another drug, rifapentine.

"I hope that new regimens of three months...or less will be shown to be effective and will replace the current regimens," Horsburgh said.

Broker presentation February 2010

Another 17 hour marathon of fumbling for tickets, boarding passes and loose connections to the city of four seasons.

Essentially the presentation made by Cellestis at Shaw Stockbrokers was to give a background briefing on the half yearly report for the financial year 2010 and many thanks to the senior executives at Shaw for hosting the presentation and to Cellestis executives Dr Tony Radford and Mr Brian Manuel for making the presentation.

The report, which can be found here, dealt primarily with the finances of the company and can be better explained by the following pictures;

Here their largest market, USA, continues to present solid and consistent growth when sales are expressed in $US.

When looking at sector revenues expressed at a fixed rate of currency Japan has obviously underperformed. This situation has been ongoing and in part can be explained by the rate of Government reimbursement (Hoken) not providing sufficient incentive to users. This has recently been increased, by ~28%, which will have an impact on sales.

Clearly the large swings in foreign exchange over the period have also made an impact on income. What is important to remember is that to a large extent costs are also made in that foreign currency thereby providing a natural hedge. The dilemma then is to determine the best time to repatriate income to Australia.

There was also discussion on current and future directions and developments, most of which were of a subtle and technical nature requiring some background knowledge.

In discussion outside the presentation it became apparent that the business may have developed beyond the point where it can easily understood by some investors. For those focussed on bottom line financials and profit/earning ratios the recent report may not be sufficient reason to maintain their investment and perhaps this factor explains the recent share price sell down that has disappointed some. For others the development in intellectual property is compelling.

Personally I find these southern sojourns invaluable. Each presentation is unique in that it covers new territory and over time has helped to build up a more comprehensive profile.

More on that LTBI bean counter study

Another aspect to the LTBI cost effectiveness study (previously discussed here) is the rate of return for the TST

We assumed that there will be a stringent follow up of contacts thus we used a return rate of 90%. In reality, up to 60% of individuals fail to return for their TST results [27, 28]

and they then admit that

At these lower return rates, single IGRA strategies become more cost-effective than their dual strategy counterparts.

Was there a cost given for the "stringent follow up of contacts?"

A tale of two tails

Whilst Lodge display confidence in Cellestis

We assess Cellestis as a BUY with a spot valuation of $4.49 and a 12 month price
target of $5.05.

BioShares were less than impressed

.. based on current sales growth rates and the company’s capitalisation, the stock appears overvalued.

Bioshares recommendation: Sell

If we assume the target of 30% market penetration by 2020 (ex Lodge) and allow that the market is 50M tests pa (ex Lodge) and the revenue for each test is $A17 (ex forrestgump) we can calculate that a sales growth of ~27.7% pa from 2007 should meet that target

By comparing the projected with the current sales growth we can see that current sales is well ahead of the projection.

The recent HY result, of a sales growth of 26%, confirms that trend

NHS ltbi cost effectiveness study

Hot off the presses is the Different screening strategies (single or dual) for the diagnosis of suspected latent tuberculosis: a cost-effectiveness analysis.

A reasonably contentious statistical analysis heavily reliant on various assumptions.

this conclusion is sensitive to screening test assumptions and LTBI prevalence.  

At first glance it appears that the study appears to be primarily concerned with the costs of diagnosis, not the long term consequences of diagnosis

More budgetary woes

From cash strapped California

Public care for Ukiah and Fort Bragg patients diagnosed with latent tuberculosis narrowly escaped cancellation during the Tuesday Mendocino County Board of Supervisors meeting -- at least until July.

Its not the first time Californian TB clinics have faced the axe

Federal grants for TB programs have declined in the last two years, and the TB section lost six employees in the current funding year, said Dr. L. Masae Kawamura, director of San Francisco's TB Control Section. The new year is expected to bring additional budget cuts at the local, state, and national levels.

"If we have five multidrug-resistant [MDR TB] cases in San Francisco this coming year, we're not going to have enough funding to manage them," said Kawamura. "We've already changed our operations to be lean, mean, and efficient, but there's a point where you've done everything you can, and that's where we are now."

Areas in Arizona are also feeling the pinch

Annual state funding to the county's TB program dropped from $167,000 in 2008 to $76,000 last year, county clinic manager Anne Davis said. The county's TB program is funded by a blend of county, state and federal funds.

Cash crisis

For some considerable time it appeared that the A G Holley Hospital would be closed. Opened in 1950 as one of the four state tuberculosis hospitals in Florida it was designed for 500 TB patients plus accommodation for medical staff and laboratories. Due to better medication the number of beds declined to 50 with closure being canvassed - A G Holley was the last TB sanitorium left in the US. Politically the hospital was finished

The Florida House just voted to shut down Lantana’s A.G. Holley Hospital, the nation’s last freestanding, state-run tuberculosis hospital.

The vote was 86-27, with Republicans supporting the plan and Democrats divided. While many Democrats spoke out against closing the hospital, Rep. Mary Brandenburg, D-West Palm Beach, voted for it. Her district includes A.G. Holley.

QuantiFERON gets the front page

In a cover story written for the peer reviewed Medical Laboratory Observer Cara Weisbrod explains how the new TB immigration guidelines will affect TB testing

Financial Planners put to the stress test

Hedge fund manager Peter Hempton from Bronte Capital believes that the assets of Managed Investment Scheme Astarra (or Trio Capital) are just bits of paper of debatable value and that liquidation of the assets is the only way to determine their true value. The Association of Independently Owned Financial Planners (AIOFP) rejects that claim and want the administrator sacked. Hempton claims that there is a conflict of interest as members of the AIOFP also hold assets in Astarra and they do not want them to be exposed to valuation. The AFIOP claim that they have been

shown “convincing evidence” proving the location of various tranches of missing investor funds.

Hempton disputes this and had accepted the bet by Peter Johnston of the AFIOP that the missing money will be found. Hempton then set the bet at $100K at odds of 3:2 with the money to held by Morningstar or the SMH. A the SMH reports

Breakthrough in TB treatment?

Shortening TB treatment times and/or reducing side effects of TB treatment would be of enormous benefit to eradicating TB.

The National Academy of Sciences has this article describing recent advances in the molecular biology of TB

We identified a potent and selective mPTPB inhibitor I-A09 with highly efficacious cellular activity from a combinatorial library of bidentate benzofuran salicylic acid derivatives assembled by click chemistry

whilst Indiana University have put it in laymans terms

The Beijing strain of TB

An article in the current Lancet discusses the Beijing genotype strain of TB and hypothesises that this more virulent, drug resistant and lethal form of TB evolved in response to the human immune system.

Reports from Africa indicate that the Beijing strain is surging ahead as

this strain had evolved unique properties that allowed for both acquisition and transmission of drug resistance

whilst a survey of MDR-TB in Europe found the Beijing strain to be present in a majority of cases. Another study from the Netherlands found that

Beijing genotype strains have a higher capacity to withstand tuberculosis treatment, even in the absence of drug resistance

The Beijing strain has the potential to challenge conventional TB diagnosis and treatment, which might be found to be both insufficient and inadequate.

Summary of the Lancet article below the fold

Lodge report - Cellestis

Hot off the press, their recommendation is a BUY with a spot valuation of $4.49 and a 12 month price target of $5.05.

Full details over at forrests place

Costs of screening migrants for TB

Now that I have the full version of the cost effectiveness study more detail is at hand.

Testing for latent TB in high risk groups

Swiss Medical Weekly provided the following study into testing for latent TB in haemodialysis (HD) patients using QuantiFERON TB Gold In Tube (QFT-GIT)

What's the big deal with Rifampicin?

Along with the other TB drugs the antibiotic known as Rifampicin has various attributes; it can induce

• hepatoxicity
• flu like symptoms
• rashes and hot flushes
• nausea, vomiting
• breathing problems

It is little wonder that those diagnosed with latent TB are reluctant to commence therapy, especially those who are familiar with the known side effects - health care workers

We were all told

that sales for this period would be no more than 37%

And they were right

For the same period receipts were up by 35.4%.

Drug resistant TB - the too hard basket?

Studies from Africa indicate that drug resistant TB is proving to be difficult to pin down. By following MDR-TB and XDR-TB patients in South Africa researchers were able to build up some data on their contacts and the results are not good;

Approximately half of adult household contacts of drug resistant TB cases had resistance profiles that differed from the index case of TB.

This indicates that in these communities drug resistant TB infection is easily transmitted by contact outside the family unit.

Mycobacterium

Over on his site ForrestGump is tackling the A-Z of CST; by any measure a daunting task. His 2nd instalment concentrates on the mechanics of the bug;

TB is a very nasty bacterium found in every county in the world that results in around 2 million deaths per year.

It's probably worth taking a backward step by mentioning that TB is a bacteria and that bacteria are absolutely everywhere. As an example, there are 40 million bacterial cells in a gram of soil and a million bacterial cells in a milli litre of fresh water. Finding bacteria is no problem, establishing their identity can be one.

Japan - TB in immune compromised patients

Also from JATA; interestingly it was found that after 6 years many were still unaware of the correct guidelines

It became clear by questionnaires that many medical dialysis did not know about the recommendation of treatment for latent tuberculosis infection from the Japanese Society for Tuberculosis.

Japan - an overview of QuantiFERON implementation

In the latest publication by the JATA a discussion on QFT - problems were noted and solutions offered

Parsing the Persians

Skorpian has made the following comment on the Iran study;

Rog

Much as I think QFT G or QFT IT is a wonderful test, I think something is getting lost in the translation in this article from Iran

They cannot say: “it may be useful for the diagnosis of both LTBI and active TB, without the need for other tests.”

QFT and active TB

Published in the latest Swiss Medical Weekly comes this study from Iran. Importantly they discuss and assess the methods for diagnosing TB viz

• chest X-ray
• sputum smear, culturing
• polymerase chain reaction, PCR
• PPD skin test
• QuantiFERON-TB Gold
• T-SPOT TB

and then studied the results of QuantiFERON for the diagnosis of previously confirmed active TB patients. Their results confirmed those of a number of studies made elsewhere and based on these results they formed the opinion that in low incidence populations QFT alone could be used to diagnose both active and latent TB;

our study confirms results of other studies applying this method for diagnosis of active TB. Although the QFT-TB Gold showed high sensitivity and specificity in low-risk populations, in such populations it may be useful for the diagnosis of both LTBI and active TB, without the need for other tests. However, in high incidence regions, we think it should be used as a supplementary tool for diagnosis of active TB together other diagnostic test as CDC suggests in its Guidelines.  

Public health - again

We saw it online in 2009 and now it is in print, in the peer reviewed Thorax Journal;

For immigrants from high risk countries QFT blood testing followed by CXR (x-ray) is feasible for TB screening, cheaper than screening using the NICE guideline and identifies more cases of LTBI.

More on public health policy

Following previous posts on QLD health and Korea Skorpian has made the following observations;



Rog,

Now that I am wandering aimlessly around the www, I thought I continue with some of the medical discussion posts that I did previously.  Hopefully they will be useful educationally for others who read your site.

No doubt Queensland Health is on the critical list .. but a few thoughts on your post with regards to diagnosing active Tb.

I can see how the comment on not using TST and IGRA to diagnose active Tb seems in contrast to what we know about Quantiferon (QFT) that in studies it can assist in the diagnosis.

Queensland Health - on the critical list

Amongst the comments on forrestthinks was this one from Thumbs Up;

The Australian National Tuberculosis Advisory Committee recommends tuberculin skin testing as the standard test for latent tuberculosis infection with targeted use of interferon gamma release assays (Quantiferon Gold) when high specificity is desired.

These tests have no role in initial investigations for active tuberculosis because negative results do not exclude disease and positive results may not necessarily indicate disease.

This statement was made by Anastasios Konstantinos, Director of Queensland TB Control Centre (Specialised Health Services), Queensland Health, Brisbane and can be found here.

Those with experience of TB would argue differently. The most reliable method of diagnosing active TB (pulmonary) is through sputum culture however this can take many weeks. Non pulmonary TB requires specific analysis which can also be unclear. Therefore the reality is that it is

common practice to initiate antituberculous treatment on the basis of initial clinical diagnosis, independent of subsequent culture confirmation. For those in whom infection is confirmed by culture, treatment is obviously continued, but in some patients confirmation is not possible; consequently, the accuracy of the initial clinical diagnosis is of paramount importance.

Nobody is saying that QuantiFERON is 100% for active TB, what they are saying is that

a positive QFT result is not a diagnostic standard for active TB; it is simply another aid towards diagnosis that can be highly effective in many situations.

Anastasios Konstantinos appears to dismiss QuantiFERON on the grounds that it is not 100% reliable however he does recommend radiology

a normal chest X-ray almost excludes pulmonary tuberculosis

"Almost excludes" is an inconclusive term suggesting that X-rays are inconclusive. Japan is a country with a long history of X-rays and TB and their experience is that

Sensitivity of chest X-ray for early diagnosis of recurrent pulmonary tuberculosis is not very high, and bacteriological examinations are more important irrespective of chest X-ray finding..

..usefulness of chest X-ray is considerably limited

Logically in its early stages TB would be difficult to pick up with a chest X-ray and with non pulmonary TB chest X-rays are totally ineffective. This point was made by epidemiologists employed by Australian Government(s) and published in the Medical Journal of Australia

Control of TB in Australia is facilitated through entry screening of migrants using chest x-ray, and contact tracing of people with active TB.11 However, this strategy is inadequate for detecting latent and non-pulmonary disease and is unlikely to identify migrants whose TB will be diagnosed many years after their arrival.

Mr Konstantinos may wish to speak with his Doctor.

Non compliance of TB treatment

With previous reports indicating that a large proportion of TB patients fail to start and/or complete TB therapy there is a need to understand the reasons just why this is occurring. Writing in Lung India Ashutosh N Aggarwal recently argued that diagnosis of TB has an emotional aspect

Most patients are worried, frustrated, or disappointed by the diagnosis, and almost a quarter do not initially accept their diagnosis.

TB - before and after treatment

A fairly recently published review of TB patients found that even after completion of the medication many did not return to full health. The assessment is of health-related quality of life (HRQL)

HRQL broadly describes how well individuals function in daily lives and their own perception of well-being in physical, psychological, and social aspects

and the evidence suggests that TB diminishes a patients HRQL. Whether the cause is psychological, physiological or social, or a combination of, remains unclear. One method to measuring overall health is the SF-36 or short-form health survey of 36 questions.

Sharescene - one last time as I am over it.

More activity from "anon",  possibly Sharescene administration, in an effort to "tell their side of the story" by way of comments made on forrestthinks.

In reading your email you say in one line say youve been moderated only once in 5 years / 2400 posts and then the next line claims the place is over moderated.

How can it be both? Either you get moderated all the time and hence the place is over moderated or they dont moderate that often.

Whoever he is he just doesnt get it, "over moderated" does not refer to the frequency of moderation it refers to the excessive nature of the moderation ie quality -vs- quantity

Latent TB in HCWs - a tale of neglect

From Montreal comes this study into latent tb testing of 630 HCWs and the results are not good;

546 were foreign-born,
443 reported previous BCG vaccination,
210 were positive for latent TB (+10mm lumps),
165 began treatment
115 completed treatment.

In another study of public and private clinics in 19 regions of the United States and Canada in 2002

Less than half of persons starting treatment for latent tuberculosis infection completed therapy.

No reason was given as to why they had failed to complete the course.

TB treatment in Haiti - shaken to the core

 

Clervil Orange, a patient at what remains of Haiti's only 

TB hospital, getting a haircut this week. "Why don't you just

leave us to die?" he asked the lone nurse there. 

------------------------------------------------------

On top of all the other misery that exists within Haiti the failure to continue TB treatment presents another burden

In normal times, Haiti sees about 30,000 new cases of tuberculosis each year. Among infectious diseases, it is the country’s second most common killer, after AIDS, according to the World Health Organization.

The situation has gone from bad to worse because the earthquake set off a dangerous diaspora. Most of the sanatorium’s several hundred surviving patients fled and are now living in the densely packed tent cities where experts say they are probably spreading the disease. Most of these patients have also stopped taking their daily regimen of pills, thereby heightening the chance that there will be an outbreak of a strain resistant to treatment, experts say.

At the city’s General Hospital, Dr. Megan Coffee said, “This right here is what is going to be devastating in six months,” and she pointed to several tuberculosis patients thought to have a resistant strain of the disease who were quarantined in a fenced-off blue tent.

Story link here and full story below the fold

Has Sharescene lost the plot?

If you read the blurb you might think that Sharescene is a good place to pick up information;

Read what 19,500+ other Australian investors have to say about the shares you follow and get your questions answered by fellow investors.

The reality is that all of those 19,500+ posters are subject to the scrutiny and censorship of the Sharescene administration.

Flying pigs

News of banking woes amongst the PIGS (Portugal, Italy, Greece and Spain) has sent stock markets tumbling, or so we are told. Reuters reports that the

latest flow figures from fund tracker EPFR Global actually show a small net inflow of $861 million into European equity funds, including Britain, in the week to February 3, with flows to Germany and France prompted by more attractive valuations created by a lower euro.

which prompted the observation that

sharp market movements in the past week -- including the euro falling to an eight-month low of $1.3646 on Friday -- are more the result of short-term trading than larger, long-term investment decisions.

Says Santander Asset Management

"We don't see any fundamental moves at all. It's purely speculative, it's the question of unknowns. This is a short-term evolution rather than long-term."

This would tally with BCA who say that shares are fully priced leaving them vulnerable to "minor disappointments"

Indeed, there are two potential scenarios for emerging market stock prices: either a full-fledged mania will develop with multiples continuing to expand, or, a setback/period of indigestion will occur before a new upleg develops. Currently, the odds of a mania-type pattern developing in emerging markets are not significant.

Full time traders are getting rolled

Oil is down 3 bucks and the Dow is getting steam rolled to the tune of 100+ points. Some people think this is all dollar related. However, I happen to think it is panic related. The market is taking the path of least resistance and I am simply watching my gains wilt away into losses, almost in a catatonic “deer in headlights” demeanor. Naturally, the correct trade was to jump into the FAZmobile or get short. Oh, but that shit was not for me and I’ll tell you why..

whilst for shorters it's business as usual

But I don’t think this is the beginning of a new bear market. Frankly, the earnings news has been too good and is suggestive of a short/intermediate term bottom in the economy..

..I think we enter a more rational, stagnant, range bound, bloated market environment..

..Now we can just work through all the stimulus and bailouts that are jacking up the economy and stock market and try to let markets and the economy to sort it all out and reach some kind of equilibrium.

More on prediction of progression to active TB

Haldar et al, from Leicester Hospitals UK, presented a study of TB contacts to the British Thoracic Society, 2009.

The study was of 2204 contacts using QuantiFERON® TB Gold In-Tube and TST.

Pai answered

In their meta-analysis: New Tests for the Diagnosis of Latent Tuberculosis Infection: Areas of Uncertainty and Recommendations for Research the authors comment on discordant results between IGRA and TST

Discordant tuberculin skin test and IGRA reactions were frequent and largely unexplained

The study Evaluating the non-tuberculous mycobacteria effect in the tuberculosis infection diagnosis just published in the peer reviewed ERS Journal explains that discrepancy

In summary, our results show enough evidence to state that previous NTM sensitisation in children induces false-positive results in the TST for diagnosing LTBI and that the IFN-y tests could avoid both unnecessary chemoprophylaxis treatment among child populations and consuming resources searching the index case.

.

Conflict of Interest

Cellestis has always maintained that the number of peer reviewed studies on QuantiFERON was a valuable marketing tool and that they

have been important to the company’s success. Peer review clinical papers now exceed 400 and are growing. This has been a tremendous assistance in getting guidelines written

(Radford, Bioshares Thredbo 2009)

One of the criteria for submitting studies for peer review is that any conflict of interest be declared. Consider the case of 

Go West!

"Skinny Monkey" is the nickname of a 21 year old medical student from Malaysia who is in her 4th year MBBS at UWA in Perth, Australia.

When Skinny Monkey was assigned Fremantle Hospital for her nursing attachment a TB test was required.

We were told to hav our mantoux test done.

When we reached there, the nurses there told us "it's a quantiferon TB test, u shud hav done it back in pathwest and not here!" So we had to walk all the way back to pathwest. We waited for 30mins in pathwest reception counter before we could get our venepuncture done.

The medical students of today are the health care workers of tomorrow.

University of Florida

Link

Childhood TB: Time for a New Paradigm?
 
Location: EPI Research Facility, Room 150
 
Date and Time: 2/3/2010 4:00:00 PM
 
Anna Mandalakas, M.D., Associate Professor of Pediatrics, Global Health & Diseases, and Epidemiology & Biostatics, Case Western Reserve University

Details:  The Emerging Pathogens Institute Seminar Series. One third of the world's population is infected by Mycobacterium tuberculosis. This source of infected persons is the driving force behind the global TB epidemic that results in 1.8 million deaths per year. Recently developed interferon Gamma Release Assays (IGRAs) promise to improve our ability to accurately diagnose latent TB infection, predict TB disease progression and aid efforts to control TB. The ideal method to evaluate these potential IGRA applications is through large, prospective, community-based studies. Dr. Mandalakas will describe her current South African research projects designed to explore these applications and other questions relevant to the control of Childhood TB.

It's the economy, stupid.

Yesterday the Reserve Bank of Australia announced that they were keeping interest rates on hold.

Tunnel vision

Link

Ophthalmology 117, 2 (2010)

Friederike Mackensen, Matthias Becker, Stefan Zimmermann

We write regarding the publication of Ang et al, “Diagnosis of tuberculous uveitis: clinical application of an interferon-y release assay.” The authors present a well-performed study to evaluate the usefulness of the QuantiFERON (QFT) Gold test in the diagnosis of tuberculosis associated uveitis. We read the results with great interest as we ourselves work with this test and have published on the subject. Therefore, it took us by surprise that the authors state in their introduction, “the role of IGRAs [Interferon-y release assays] in the diagnosis of TB [tuberculous] uveitis is not well studied.” Towards the end of the paper they state, “This is the first and largest study of its kind to evaluate the use of QFT in the clinical diagnosis of uveitis.” A brief Medline search of papers published and or entered into PubMed by August 2008 (Ang et al first submitted their publication on September 7th) with the key words “quantiferon” and “uveitis” results in 3 publications, out of which not one is cited by the authors. One was published in 2006 and the 2 other papers were electronic publications from May and August 2008.

The Medline search is here with the relevant studies being

QuantiFERON TB-Gold--a new test strengthening long-suspected tuberculous involvement in serpiginous-like choroiditis

Initial results of QuantiFERON-TB Gold testing in patients with uveitis.
 
Gamma interferon assay as an alternative to PPD skin testing in selected patients with granulomatous intraocular inflammatory disease.

The reality of false positives

Prolific blogger and mother of four OmomK talks about her volunteer work (subbing)

One of the trips was to fill out paperwork to get on the sub list for one of the school districts. Yay! I should be processed shortly.

However, they needed me to take a TB test (even though I had one in August from my primary care physician and it was negative), which was read today. It came back positive.

As soon as she heard the result she knew that it was a dud

North Carolina - denying the science

Having thought a little about the position that North Carolina have taken on latent TB testing, it's worth running through a few of their comments.

Primarily they give the appearance of accepting the science

North Carolina TB guide update

North Carolina has recently sent out a memo advising TB nurses of Changes to the 2007 TB Policy Manual. In particular interferon gamma release assays (IGRA) are discussed here. In essence they say that

The Mantoux tuberculin skin test is the most accurate skin test for determining TB infection and is the only skin test recommended by TB Control.

Fair enough, they are only talking about skin tests. When it comes to IGRAs there are all the usual caveats and uncertainties however they have recommended that IGRA be used for screening

• at sites where tuberculin skin testing is not frequently performed
• if the patient is unlikely or unwilling to return for reading of the tuberculin skin test
• in populations with sub optimal health care access/utilisation (eg. the homeless, drug users, migrant workers)
• in contact situations of children +5 years of age and adults

In general they have emphasised that with TB testing

Medicine is constantly changing, and IGRAs are a very active area of research. Clinical judgment based on the latest scientific evidence, with emphasis on how a given test will affect patient management, should always be used in deciding to order any diagnostic test and in interpreting the results

.