A new study by researchers at University of California-San Francisco and Makerere University-Kampala has shown that HIV-infected patients who are falsely diagnosed as having tuberculosis (TB) have higher rates of mortality than those who are correctly diagnosed with the disease.
"Among HIV-infected persons with suspected TB, falsely diagnosing persons with TB by rapid testing was associated with increased mortality when compared with the group of patients who received the correct diagnosis," said study lead author Robert Blount, clinical fellow in pulmonary and critical care medicine at UCSF's School of Medicine.
The diagnosis of TB in HIV patients is particularly important, because of their increased susceptibility to the disease and the time that the standard sputum culture test takes to reveal results.
In this study, Dr. Blount and his colleagues evaluated the outcomes of 600 HIV-infected patients who were treated at Mulago Hospital in Kampala, Uganda, including patients who were incorrectly diagnosed with tuberculosis following rapid testing.
"Studies tend to emphasize the negative impact of missing the diagnosis of TB. Our study shows that falsely diagnosing patients with TB who do not actually have TB is also associated with negative outcomes," Dr. Blount noted.
Because physicians believe tuberculosis is the culprit, any search for the real underlying disease is delayed, as is proper treatment, he said.
"These results remind us as clinicians that diagnostic tests are not 100 percent accurate, and that falsely diagnosing patients with a disease who do not actually have that disease can lead to negative outcomes," he said.
"We must continue to re-evaluate a patient's clinical progress. If he or she is not responding as predicted to treatment for a diagnosed disease, we must entertain alternative diagnoses," he added.
Dr. Blount also noted the results indicate a need for further refinement of rapid diagnostic tests for tuberculosis.
The results of the study will be presented at the ATS 2010 International Conference in New Orleans.