A Fast Track for TB Diagnosis
Luke Davis, MD, Associate Professor of Epidemiology (Microbial Diseases) and Associate Professor of Medicine (Pulmonary, Critical Care, and Sleep Medicine) at Yale School of Public Health, has always been interested in tuberculosis (TB), particularly diagnosis.
In 2010, Davis and colleagues at the University of California San Francisco worked in Uganda with its Ministry of Health to evaluate a novel molecular diagnostic technology for TB. The test was developed by Cepheid Diagnostics, the Foundation for Innovative New Diagnostics, and the Bill and Melinda Gates Foundation with the goal of diagnosing more TB patients more quickly and rapidly diagnosing drug-resistant TB. The results were promising to say the least: the New England Journal of Medicine headline read simply: “Time for a Game Change.”
During their time abroad, Davis and his colleagues began to wonder if the technology would ever become transferable to the United States. While TB is often under-diagnosed in low-income countries, it is commonly over-diagnosed in the United States. “Studies show that less than 10 percent of patients placed in respiratory isolation in hospitals will actually have TB,” said Davis. Although active TB disease is rare in the United States, hospital systems often fear the spread of TB from patient to patient. Overuse of respiratory isolation can adversely affect patients, contributing to stigmatization and delayed care. Specialized ventilation systems are costly to build and maintain.
Back in the United States, Davis and his colleagues partnered with stakeholders in a local TB control program and in the clinical and public health laboratories to develop the evidence to support a testing program. They started first in the outpatient clinic at the San Francisco Department of Public Health and later moved to the inpatient setting at Zuckerberg San Francisco General Hospital.
For the inpatient study, excess sputum submitted for routine TB testing was tested using the new method, with clinical staff and research staff blinded to each other’s results. The research team recorded the amount of time required to turn around a result, and compared the accuracy of the method to conventional rapid tests in reference to the gold standard of culture. At this stage, the results could not be reported to patients, as the method was not yet FDA-approved.
“Rather than have patients wait three days, we wanted to determine, hypothetically, if we could safely release patients from isolation within a few hours. We concluded that, if this information had been available and communicated to a clinician, and that they had discontinued isolation, the average patient would have saved 60+ hours in respiratory isolation,” said Davis.
In 2013, the U.S. Centers for Disease Control and Prevention (CDC) announced FDA approval of the Cepheid Diagnostics TB test in the United States, and in 2015, the CDC issued an updated guidance authorizing use of the method as a rule-out test for triage of inpatient isolation beds. “By that point, we had already decided we had to implement this test. Our hospital was 100 percent behind us, but wanted proof, so they awarded us a Choosing Wisely grant to evaluate its impact,” said Davis.
In the implementation phase of the project, Davis and a broad group of stakeholders developed educational materials and an algorithm for clinicians, and an order set for the electronic health record as a prompt. Davis and his team also created a website and hotline to help troubleshoot issues experienced by those interested in implementing his approach. More than a year after implementation, the team recorded 77 percent of eligible patients tested with the method, and no missed TB diagnoses. There was a 29 percent decrease in time in isolation, a 27 percent decrease in length of stay, and average savings of $13,347 per TB-negative patient in isolation.
“Faculty interest in reducing waste made this program an example of what can be achieved when resources are more appropriately directed, particularly for vulnerable populations where resources are scarce,” said Davis. Sustainability of the initiative was secured through continuation of laboratory funding and the efforts of champions in the Zuckerberg San Francisco General Hospital Infection Control Department and the San Francisco TB Control Program.
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