Global burden of chronic pulmonary aspergillosis as a sequel to pulmonary tuberculosis

OBJECTIVE: To estimate the global burden of chronic pulmonary aspergillosis (CPA) after pulmonary tuberculosis (PTB), specifically in cases with pulmonary cavitation. METHODS: PTB rates were obtained from the World Health Organization and a scoping review of the literature was conducted to identify studies on residual pulmonary cavitation after PTB and estimate the global incidence of CPA after PTB. Having established that from 21% (United States of America) to 35% (Taiwan, China) of PTB patients developed pulmonary cavities and that about 22% of these patients developed CPA, the authors applied annual attrition rates of 10%, 15% and 25% to estimate the period prevalence range for CPA over five years. Analysis was based on a deterministic model. FINDINGS: In 2007, 7.7 million cases of PTB occurred globally, and of them, an estimated 372,000 developed CPA: from 11,400 in Europe to 145,372 in South-East Asia. The global five-year period prevalence was 1,174,000, 852,000 and 1,372,000 cases at 15%, 25% and 10% annual attrition rates, respectively. The prevalence rate ranged from < 1 case per 100,000 population in large western European countries and the United States of America to 42.9 per 100,000 in both the Democratic Republic of the Congo and Nigeria. China and India had intermediate five-year period prevalence rates of 16.2 and 23.1 per 100,000, respectively. CONCLUSION: The global burden of CPA as a sequel to PTB is substantial and warrants further investigation. CPA could account for some cases of smear-negative PTB. Since CPA responds to long-term antifungal therapy, improved case detection should be urgently undertaken.