Diagnosing Chronic Pulmonary Aspergillosis in Treated Pulmonary TB

Chronic pulmonary aspergillosis complicates treated pulmonary tuberculosis (TB) frequently enough to represent an unrecognized global public health issue, according to a study published in the European Respiratory Journal.

Because pulmonary TB largely occurs in resource-poor settings, where access to computed tomography (CT) thorax and Aspergillus-specific IgG testing is limited, researchers in the present study evaluated the accuracy of chronic pulmonary aspergillosis diagnosis by chest radiograph, with or without serology, in comparison with confirmed disease by CT thorax.

In this community-based, cross-sectional prospective survey, 398 patients from Gulu, Uganda, were recruited, with 50% of patients having an HIV co-infection. Median time from completion of TB treatment to recruitment was 29 months.

In the initial survey, low CD4 counts were uncommon in patients with HIV. Cough and cavitation on chest radiograph were more common in patients without HIV, with 11 patients meeting the criteria for probable chronic pulmonary aspergillosis.

Two years later, 285 patients were resurveyed and CT thorax was performed on 73 suspected chronic pulmonary aspergillosis cases. Definite chronic pulmonary aspergillosis was diagnosed in 14 patients. Chronic pulmonary aspergillosis was more common in patients with chest radiograph cavitation than in those with no such cavities (26.1% vs 0.8%; P <.001), and possibly less frequent in patients with HIV compared with patients without HIV (3% vs 6.7%; P =.177).

The annual rate of new chronic pulmonary aspergillosis development between surveys was 6.5% in those with chest radiograph cavitation and 0.2% in those without (P <.001). No associations were found between diagnosis of chronic pulmonary aspergillosis and potential clinical and radiological risk factors. Cough and hemoptysis were significantly more common in those with raised Aspergillus-specific IgG, but other symptoms were not.

Although all chronic pulmonary aspergillosis cases had either cavitation or pleural thickening on chest radiograph, no combination of chest radiograph findings and clinical assessment produced a positive predictive value above 40%. However, Aspergillus-specific IgG measurement, chest radiograph cavitation, and chronic cough or hemoptysis allowed chronic pulmonary aspergillosis diagnosis with positive predictive value of 92.3% and negative predictive value of 99.3%.

Findings from the study suggested that chronic pulmonary aspergillosis can be excluded by chest radiograph and diagnosed with acceptable accuracy if Aspergillus-specific IgG measurement is also performed.

Although the following proposal will need to be validated in another population, the investigators suggest [chronic pulmonary aspergillosis] “should be diagnosed in persons with treated [TB] in resource-poor settings if recurrent [TB] has been excluded by GeneXpert [polymerase chain reaction] testing and a combination of raised Aspergillus-specific IgG, chest X-ray cavitation and either chronic cough or haemoptysis is present.”

Disclosure: The study was funded by an investigator-driven study grant from Astellas Pharma Europe Ltd.

Reference

Page ID, Byanyima R, Hosmane S, et al. Chronic pulmonary aspergillosis commonly complicates treated pulmonary tuberculosis with residual cavitation [published online January 31, 2019]. Eur Respir J. doi: 10.1183/13993003.01184-2018

This article originally appeared on Infectious Disease Advisor