Abstract
Allergic bronchopulmonary aspergillosis (ABPA) complicates asthma and may lead to chronic pulmonary aspergillosis (CPA) yet global burdens of each have never been estimated. Antifungal therapy has a place in the management of ABPA and is the cornerstone of treatment in CPA, reducing morbidity and probably mortality. We used the country-specific prevalence of asthma from the Global Initiative for Asthma (GINA) report applied to population estimates to calculate adult asthma cases. From five referral cohorts (China, Ireland, New Zealand, Saudi Arabia and South Africa), we estimated the prevalence of ABPA in adults with asthma at 2.5% (range 0.72–3.5%) (scoping review). From ABPA case series, pulmonary cavitation occurred in 10% (range 7–20%), allowing an estimate of CPA prevalence worldwide using a deterministic scenario-based model. Of 193 million adults with active asthma worldwide, we estimate that 4,837,000 patients (range 1,354,000–6,772,000) develop ABPA. By WHO region, the ABPA burden estimates are: Europe, 1,062,000; Americas, 1,461,000; Eastern Mediterranean, 351,000; Africa, 389,900; Western Pacific, 823,200; South East Asia, 720,400. We calculate a global case burden of CPA complicating ABPA of 411,100 (range 206,300–589,400) at a 10% rate with a 15% annual attrition. The global burden of ABPA potentially exceeds 4.8 million people and of CPA complicating ABPA ˜ 400,000, which is more common than previously appreciated. Both conditions respond to antifungal therapy justifying improved case detection. Prospective population and clinical cohort studies are warranted to more precisely ascertain the frequency of ABPA and CPA in different locations and ethnic groups and validate the model inputs.
Acknowledgments
We are indebted to Joanne Gill and library staff for sourcing the papers and to multiple colleagues who answered questions about the frequency of disease in their country including Ashok Shah, (Vallabhbhai Patel Chest Institute, University of Delhi), Rick Moss (Stanford University), Alan Knutsen (St Louis University), Ray Slavin (St Louis University), Tony Catanzaro (University of San Diego), David Stevens (Stanford University) and Peter Gergen (NIH, Bethesda).
Funding
University Hospital of South Manchester, Manchester, UK.
Declaration of interest: Dr Denning holds founder shares in F2G Ltd, a University of Manchester spin-out company and has received grant support from F2G as well as the Fungal Research Trust, the Wellcome Trust, the Moulton Trust, The Medical Research Council, The Chronic Granulomatous Disease Research Trust, the National Institute of Allergy and Infectious Diseases, National Institute of Health Research and the European Union, AstraZeneca and Basilea. He currently or previously acted as an advisor/consultant to F2G, Basilea, Vicuron (now Pfizer), Pfizer, Schering Plough, Nektar, Daiichi, Astellas, Gilead, York Pharma and Lab21. He has been paid for talks on behalf of Schering, Astellas, Novartis, Merck, Dainippon and Pfizer. Alex Pleuvry is a Director and shareholder in Oncalex, an independent consultancy, with no specific financial interest in respiratory or fungal disorders. Dr Cole is a tenured professor, with consultancies on environmental health to public health units but none on respiratory or fungal disorders or their treatment. The authors report no conflicts of interest. The authors alone are responsible for the content and the writing of the paper.