An estimated 4,837,000 asthmatics with allergic bronchopulmonary aspergillosis (ABPA) could benefit substantially from antifungal treatment, say researchers from the University of Toronto and Manchester University.
Their work, published today in the journal Medical Mycology, has also re-estimated the total number of asthmatics worldwide -- to reveal a staggering 193 million sufferers. Twenty-four million asthma sufferers live in the United States, 20 million each in India and China, and seven million in the United Kingdom.
Clinical studies have shown that oral antifungal drugs significantly improve symptoms and asthma control in asthmatics with ABPA, treatment endorsed by the Cochrane Collaboration. This is the first time that a global estimate of ABPA numbers has been made.
In national league tables of asthma rates in adults, only Australia and Sweden have a higher prevalence than the UK. In global league tables of ABPA occurrence, New Zealand tops the list with a 3.5% rate in new patients attending chest clinics at hospitals. The rates were 2.6% in Cape Town, 2.3% in Saudi Arabia, 2.5% in China and 0.7% in an older study from Ireland. No population-based studies have been done.
In addition to standard asthma therapy, the antifungal therapy used is itraconazole -- now a generic, inexpensive antifungal -- with a response rate of 60%. The researchers also found that antifungal therapy also benefits patients with severe asthma sensitized to fungi, called SAFS.
Alternatives include voriconazole and posaconazole, which have 75-80% response rates. In a recent assessment of voriconazole and posaconazole for both ABPA and SAFS, 75% of patients were able to stop taking oral corticosteroids, a major benefit, and 38% of patients had their asthma severity downgraded on antifungal therapy.
Professor David Denning, professor of medicine and medical mycology at the University of Manchester and Director of the University Hospital of South Manchester's National Aspergillosis Centre, led the study into the total number of asthmatics worldwide. He said the study results implied that asthma admissions and deaths could be avoided with more extensive use of antifungal therapy.
"We were surprised by the number of patients with ABPA, and by the lack of community based studies done," he said. "Our National Aspergillosis Centre treats hundreds of these patients each year, generally with major improvement, and so a conscious program to seek out ABPA from all asthmatics is required."
Professor Donald Cole of the Dalla Lana School of Public Health at the University of Toronto was the senior author of the study and contributed his expert epidemiological knowledge to the development of the model and provided a 'reality' check of the model's estimates.
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