Detection of invasive fungal infections

Measurement of β‐D‐glucans to detect invasive fungal infection in immunocompromised people

Why is improving the diagnosis of invasive fungal infections important?
Fungal infections occur in people who are unable to fight infection, and these infections can be life‐threatening in this group of people. Fungal infections are difficult to diagnose. Failure to recognize a fungal infection when it is present (a false‐negative test result) leads to delayed treatment and poorer outcomes. An incorrect diagnosis of infection (a false‐positive result) may result in wasted resources and unnecessary investigation and treatment.

What is the aim of this review?
The aim of this review is to find out how accurate a blood test is for diagnosis of fungal infections in people who are unable to fight infection. Review authors included 49 studies to answer this question.

What was studied in this review?
Five kinds of blood tests were compared. All of these tests use similar biochemical methods to detect the presence of a sugar molecule (β‐D‐glucan) that is a component of the fungal cell wall. This molecule does not normally occur in blood, so its detection indicates that fungi are present. The tests require a blood sample, which is then sent to a laboratory for analysis. Diagnosis of fungal infections is difficult, and the diagnosis is often made only after the disease has advanced. Blood tests can provide an earlier diagnosis, so they would offer an advantage over current methods.

What are the main results of the review?
This review included studies of 6244 people who were at risk of getting fungal infections. Study results show that accuracy varied widely across studies. The variation was so great that it was not possible to obtain a reliable estimate of the accuracy of the various tests.

How reliable are results of the studies in this review?
In the included studies, the diagnosis of invasive fungal infection was made using criteria developed by the European Organization for Research and Treatment of Cancer (EORTC)*. The EORTC criteria are considered reliable and the studies were generally well conducted, so it is likely that the reference diagnoses were accurate. Accuracy of blood tests for invasive fungal infections varied widely. Some studies found that the blood test was accurate, but others found that the blood test was not very accurate. The reason for this variation is not understood.

*The EORTC criteria provide the reference diagnosis. Results of the blood test are compared to the reference diagnosis.

Who do the results of this review apply to?
Most included studies were performed at academic medical centers or public hospitals in the United States, Germany, and Italy. The most common underlying conditions were cancer (47%) and admission to intensive care (33%). A majority of participants were adults. The overall prevalence of invasive fungal infection was 28%.

What are the implications of this review?
Accuracy of the diagnosis varied widely across studies. It is not clear whether testing can accurately detect invasive fungal infections. Testing accurately detects disease in some studies, but in others it does not. The reasons for the variation in accuracy are not understood.

How up‐to‐date is this review?
The review authors searched for and reviewed studies published up to June 2019.

Read the full review here