*4.2. Current Research on Asthma in Di*ff*erent Countries*

In terms of the countries involved in the research area, the top nine countries with the highest number of study settings belonged to the high-income group [28]. In addition to the United States, which led in research on interventions to improve quality of life of asthmatics, a large number of study settings on quality of life of people living with asthma took place in Australia, the United Kingdom and Europe (Table 2). These efforts have resulted in the stabilized or decreasing prevalence of asthma in such developed countries, as opposed to developing countries, which have been facing a steep increase in the burden of asthma [4,29,30]. It is also noteworthy that low- and lower-middle income countries accounted for more than 80% of asthma-related deaths worldwide, which calls for more empirical studies to be conducted in developing countries [5].
