Xpert MTB/RIF and Xpert MTB/RIF Ultra for pulmonary tuberculosis and rifampicin resistance in adults

07 Jun 2019

Why is improving the diagnosis of pulmonary tuberculosis important?

Tuberculosis causes more deaths globally than any other infectious disease. When detected early and effectively treated, tuberculosis is largely curable, but in 2017, around 1.6 million people died of tuberculosis. Xpert MTB/RIF and Xpert Ultra, the newest version, are World Health Organization‐recommended tests that simultaneously detect tuberculosis and rifampicin resistance in persons with tuberculosis symptoms. Rifampicin is an important anti‐tuberculosis drug. Not recognizing tuberculosis early may result in delayed diagnosis and treatment, severe illness, and death. An incorrect tuberculosis diagnosis may result in anxiety and unnecessary treatment.

What is the aim of this review?

To determine how accurate Xpert MTB/RIF and Xpert Ultra are for diagnosing pulmonary tuberculosis (PTB) and rifampicin resistance in adults. This is an update of the 2014 Cochrane Review.

What was studied in this review?

Xpert MTB/RIF and Xpert Ultra, with results measured against culture (benchmark).

What are the main results in this review?

95 studies: 86 studies (42,091 participants) evaluated Xpert MTB/RIF for tuberculosis; 57 studies (8287 participants) for rifampicin resistance. One study compared Xpert Ultra and Xpert MTB/RIF.

For PTB, Xpert MTB/RIF was sensitive (85%), registering positive in people who actually had tuberculosis, and specific (98%), i.e. it did not register positive in people who were actually negative. Xpert Ultra had higher sensitivity than Xpert MTB/RIF (88% versus 83%) in one study.

For rifampicin resistance, Xpert MTB/RIF was highly sensitive (96%) and specific (98%). Xpert Ultra gave similar results.

Xpert MTB/RIF was better for diagnosing tuberculosis in HIV‐negative than in HIV‐positive people.

How confident are we in the results of this review?

Confident. We included many studies and used the best reference standards.

Who do the results of this review apply to?

People with presumed PTB or rifampicin resistance.

What are the implications of this review?

In theory, among 1000 people where 100 have tuberculosis on culture, 103 would be Xpert MTB/RIF‐positive and 18 (17%) would not have tuberculosis (false‐positives); 897 would be Xpert MTB/RIF‐negative and 15 (2%) would have tuberculosis (false‐negatives).

Among 1000 people where 100 have rifampicin resistance, 114 would be positive for rifampicin resistance and 18 (16%) would not have rifampicin resistance (false‐positives); 886 would be negative for rifampicin resistance and four (0.4%) would have rifampicin resistance (false‐negatives).

How up‐to‐date is this review?

To 11 October 2018.