The total number of respondents interviewed with sociodemographic data was 1,220 (Figure ), of which 63.2% were male, and 20.1% were UAE Nationals, with a mean (SD) age of 32.9 (14.1) years, all according to the above mentioned quotas. In detail, sampling percentages of participants per Emirate was 34.1% Abu Dhabi, 32.2% Dubai, 19.3% Sharjah, 5.0% Ajman, 1.3% Umm Al-Quwain, 1% Ras Al-Khaimah, and 3.1% Fujairah.
CONSORT flow-chart of participants.
Results by gender and age are presented for participants 20-44 years, younger and older ages (Table ).
Demographic characteristics of participants, by age band
Prevalence of individual respiratory symptoms according to the ECRHS screening questionnaire in all participants were ranging from 8 to 10%, except for, lower for nasal allergies (6.8%) (Table ). However, when stratified by age band, it can be seen that in participants younger than 20 years, as well as those older than 44 years, prevalence of nearly all symptoms are 10% or higher, while those participants 20-44 years presented lower prevalence in all symptoms (p < 0.05).
Symptoms according to the ECRHS screening questionnaire in participants, by age band
We explored the male:female ratio of reported wheezing and of asthma attacks and its treatment by age (Figure ). The classical inversion of the male:female ratio in adolescence was not observed; in girls 5-15 years wheezing and asthma attacks were more common than in boys, while prevalence of these symptoms were evenly reported up to the age of 60 years and older. Surprisingly, reported asthma treatment showed no gender ratio and was unchanged in all age bands, namely 9.3% in participants younger than 20 years, 6.6% in participants 20-44 years, and 10.3% in participants older than 44 years (Table ).
Prevalence of wheezing (A), asthma attack (B) and asthma medication (C) by age, in male and female.
These respiratory symptoms according to the ECRHS screening questionnaire are next presented in participants 20-44 year, by gender (Table ). It can be seen that all symptoms were reported more frequently in female than male, differences being statistically significant only for "Woken up by an attack of coughing" and for "Nasal allergies (including hay fever)" (p < 0.05).
Symptoms according to the ECRHS screening questionnaire in participants 20-44 yr, by gender
Overall, there were 184 (15.4%, 95% C.I. 13.5 - 17.5) participants who fulfilled our screening criteria for asthma (Figure ). These asthmatics were more frequently male (56.5%) but there were no significant differences by age in male versus female asthmatics (Table ). As per the results in the general population, there were neither clinical nor statistical differences in the distribution of individual respiratory symptoms by gender in these asthmatics, except for "Wheezing without a cold" (p < 0.05) (Table ).
Characteristics of those responding "YES" to Q1 "wheezing", Q4 "coughing", Q5 "asthma", or Q7 "nasal" according to the ECRHS screening questionnaire (n = 184)
For consistency with ECRHS sampling methodology, results in those participants responding YES to the following three questions: "Have you been woken by an attack of shortness of breath at any time in the last 12 months?", or "Have you had an attack of asthma in the last 12 months?", or "Are you currently taking any medicine (including inhalers, aerosols or tablets) for asthma?" are presented in Table . There were 146 (12.1%, 95% C.I 10.4 - 14.1) participants who fulfilled the ECRHS asthma definition in all ages. Specifically, the ECRHS asthma prevalence in those 702 participants with 20-44 years was 9.8% (95% C.I. 7.8 - 12.2), that is in males 8.6% (95% C.I. 6.2 - 11.7) and in females 11.8% (95% C.I. 8.2 - 16.4) participating.
Characteristics of those responding "YES" to Q3 "shortness of breath", Q5 "asthma", or Q6 "treatment of asthma", according to the ECRHS main questionnaire (n = 146)
Compared to results in Table , these ECRHS-definition asthmatics were also more frequently male (57.5%), but again there were no significant differences by age in male versus female ECRHS-definition asthmatics. The distribution of individual respiratory symptoms by gender in these asthmatics were evenly distributed, again except for "Wheezing without a cold" (p < 0.05) (Table )
Finally, an approximation to asthma incidence is presented in Figure , from birth to age 50 years. As expected, the reported age of the first attack of asthma occurred more frequently in childhood and adolescence, but in males there was a peak in asthma incidence (10%) after the age of 20 years, while in females there was another peak in asthma incidence (7%) after the age of 25 years.
Self-reported age at first attack of asthma in male and female asthmatics (n = 110).