Millions Worldwide Misdiagnosed with Tuberculosis, Study Finds

Tuberculosis (TB) remains the leading cause of infectious disease death globally, but a new study reveals a concerning level of diagnostic inaccuracy. Researchers estimate that millions of people are receiving incorrect TB diagnoses each year – both false positives and false negatives – potentially hindering effective treatment and disease control efforts.

The Scale of the Problem

Published in Nature Medicine, the study analyzed data from 111 low- and middle-income countries, encompassing 6.8 million TB notifications in 2023. The findings indicate that approximately 2.05 million individuals (with a range of 1.83–2.27 million) were incorrectly diagnosed with TB (false positives). Simultaneously, an estimated 1 million people (0.71–1.36 million) received a false-negative diagnosis.

This means that as many as three out of ten individuals diagnosed with TB may not actually have the disease, even as a significant number of those who do have TB are being missed.

Why are Diagnoses Incorrect?

The study highlights the challenges faced by clinicians, particularly in resource-limited settings, when diagnosing TB. Harvard T.H. Chan School of Public Health researchers point to deficiencies in current diagnostic tools and a reliance on clinical diagnosis – assessing a patient’s symptoms – as contributing factors. Clinicians may be making the best decision for the patient, but the diagnostics they are using have big deficiencies.

False positives can occur when other conditions, such as pneumonia, lung cancer, or COPD, are mistaken for TB. False negatives mean that individuals with active TB are not identified and do not receive the necessary treatment, potentially leading to further transmission of the disease.

Implications for Public Health

The high rate of misdiagnosis has significant implications for both individual patient care and broader public health initiatives. Incorrectly diagnosing someone with TB leads to unnecessary treatment, which can have side effects and contribute to antimicrobial resistance. Missing true cases of TB allows the disease to continue spreading within communities.

As NPR reported, TB reclaimed its position as the world’s top infectious disease killer in 2023, claiming 1.23 million lives in 2024 and sickening about 10 million people each year.

Improving TB Diagnosis

Researchers suggest that scaling up new polymerase chain reaction (PCR)-based diagnostics could substantially reduce under-diagnosis. However, PCR-based diagnostics are unlikely to significantly reduce false-positive diagnoses. Major improvements will likely require more sensitive bacteriological tests – tests that detect the presence of the TB bacteria – combined with a reduced reliance on clinical diagnosis alone.

Looking Ahead

Addressing the issue of TB misdiagnosis is crucial for achieving global TB control goals. Investing in improved diagnostic tools, strengthening healthcare systems, and providing comprehensive training for clinicians are essential steps toward ensuring accurate and timely TB diagnoses for all who need them.