Researchers at the Imperial College London have found new blood tests for tuberculosis (TB) that may accelerate diagnosis and save the NHS money.


Image: NHS develops new study to diagnose TB. Photo: Courtesy of Imperial College London.

The researchers said that the current tests can be replaced with a new second generation rapid blood test, developed at Imperial.

The team stated that once the new tests are implemented, they could help doctors in quickly detecting or ruling out tuberculosis infection and help them in differentiating patients who need further investigation and treatment from those who do not pose any infectious risk to others.

TB is a bacterial infection that affects the lungs, causing cough, weight loss and fevers. It spreads through the droplets from coughs and sneezes from infected patients. T

he diagnosis and treatment of this disease at an early stage is essential for the health of the patient and also in preventing its spread to others. Thus, there is a need for rapid tests to rule out TB diagnosis in suspected cases based on blood sample.

Imperial College London, the National Heart & Lung Institute infectious diseases chairman and the leader of the study Ajit Lalvani said: “Tens of thousands of patients undergo diagnostic assessment for symptoms suggestive of TB, resulting in over 5,000 cases of TB diagnosed each year. Stopping the use of the existing, inadequate tests could save the NHS a lot of money. In contrast, the new, more accurate rapid blood test, will improve and accelerate diagnostic assessment of patients with suspected TB.”

Traditionally, the cultures, that use the patient samples such as sputum or invasive biopsies to confirm the presence of the bacterium, can take several weeks. And, a negative result does not rule out a diagnosis of tuberculosis, as the bacteria cannot be cultured from samples in a large proportion of TB patients.

The currently available rapid tests for TB used by the NHS, known as interferon-gamma release-assays (IGRAs), can help in diagnosing whether a patient has TB infection or not by detecting their immune response to TB bacteria based on a blood sample. These findings will then be confirmed with cultured patient samples in the laboratory.

Analysis of the rapid test results showed that the second-generation test has a diagnostic sensitivity of 94% in patients with confirmed tuberculosis. This means that the test gives positive result in 94% of patients with infection, which is claimed to be significantly and substantially higher than either of the existing commercially available IGRA tests, which range from 67.3% and 81.4%.

The second generation study was conducted on 845 patients with suspected TB across 10 NHS hospitals in England.

Patient blood samples were analyzed using both sets of tests, the results of which benchmarked against a confirmed diagnoses based on positive culture results.

The researchers also stated that the NHS could save more than £2m a year by implementing the second generation test. This test could be available to health services within one or two years, pending regulatory approval.