Association between socioeconomic status and the prevalence of asthma

Background The finding in some recent studies that the prevalence of asthma is higher in poor populations contradicts the hygiene theory, which claims that improved quality of life removes protective factors that prevent atopy. Objective To determine whether socioeconomic status (SES) is associated with the prevalence of asthma in adolescents in Israel. Methods The study sample consisted of 159,243 consecutive 17-year-old military recruits examined in the Israel Defense Forces. Relevant medical data were collected from the army's computerized database. The SES of the recruits was assessed according to the socioeconomic grade (by quintiles) assigned to their city or town of residence by the Israel Central Bureau of Statistics and by the number of children in the family. Results Asthma was documented in 8.5% of the male recruits and in 6.7% of the female recruits. The prevalence of asthma increased with an increase in socioeconomic grade, from 3.7% for the lowest quintile to 8.8% for the highest ( P < .001). Separate analysis of individuals from the Tel Aviv area showed that the prevalence of asthma ranged from 3.4% to 13.7% from the lowest to the highest socioeconomic quintiles ( P < .001). In Israel, having a higher number of children in the family is associated with lower SES. There was an inverse relationship between number of children in the family and the prevalence of asthma: 8.7% in families with 1 or 2 children and 1.9% in families with 9 or more children. Conclusions High SES is associated with a relatively high prevalence of asthma in adolescents in Israel.