Using the country-specific prevalence of asthma from the Global Initiative for Asthma report and applying it to population estimates, the adult asthma cases were calculated and an estimation of the burdens of ABPA and CPA were calculated by World Health Organisation (WHO) region.
Prevalence rates were estimated using two methods whereby the Global INiative on Asthma (GINA) report was employed, using their assertions of prevalence of clinical asthma was 50% of the self reported wheezing rate and a second method whereby the mean prevalence of current wheezing in children was 88% of that recorded in adults in the countries which participated in both studies. The prevalence of ABPA in adults with asthma was found to be 2.5% using five referral cohorts.
By using the following calculation the Total CPA complicating ABPA was estimated:
Asthma cases per 100,000 population per country x % of asthma in adults x proportion with cavities likely to be CPA 10% (best estimate), ranges 7-20% = Total CPA complicating ABPA
Results from the study estimated 4,837,000 patients with asthma, develop ABPA (2.5% of worldwide asthma sufferers).
By WHO region, the ABPA estimates are:
Eastern Mediterranean: 351,000
Western Pacific: 823,200
South East Asia: 720,400
A population of 411,100 of those with CPA complicating ABPA has also been estimated; making it more common that originally thought.
Such a high prevalence justifies the need for improved case detection and further investigation into the conditions to ascertain greater accuracy regarding prevalence rates in different populations (locations, ethnic groups).