Longitudinal study on the prevalence of asthma among Israeli young adults.

We studied the medical records of more than 400,000 males and females who were born in 1963-74 and examined at the age of 17-18 years, as part of the routine health assessment prior to induction into the Israel Defense Forces. As part of the assessment, each one was asked whether he/she had ever suffered from asthma or other respiratory disease. Any positive response was confirmed by a letter from the family physician and previous hospitalization records. All patients with symptoms that could be due to asthma, past or present, were referred to examination by a pulmonologist. The severity of asthma was then categorized to three grades of severity. The data were adjusted for sex and ethnic origin and Cochran-Mantel-Haenszel statistics were used to compute the association with 1 degree of freedom. The average prevalence of active disease was 2.7% for males and 2.22% for females. The prevalence of active disease increased significantly during the last decade (chi 2 = 769.25, P < 0.001). A significant association (P < 0.001) between increased active asthma prevalence and the following parameters was recorded. Asthma prevalence was higher among conscripts of European or North American origin (3.63% for males, 2.71% for females) and higher in Jews than among Druze. Increased prevalence was found among males and females who were examined at Tel-Hashomer, 3.4% and 2.41% respectively, in comparison with other geographic areas. A higher prevalence of active asthma was recorded for conscripts living in a kibbutz, 3.13% and 3.12, males and females respectively, as compared with other types of settlements. Higher prevalence was recorded for conscripts who had graduated from high school, 3.27% for males and 2.3% for females, in comparison with other levels of education. Also significantly associated with increased prevalence of active disease were other socioeconomic factors, such as a small number of children in the family and being the firstborn child. Increased prevalence of active asthma in males and females was associated with high IQ (111+), 3.5% and 2.29%, respectively. There was a higher prevalence of asthma among conscripts who were born in the summer and autumn than those born in the winter or spring. Conscripts who had asthma in the past were heavier, taller and fatter than the control group (with 95% confidence intervals). The pattern among females was much the same but did not reach significance.