Early respiratory and skin symptoms in relation to ethnic background: the importance of socioeconomic status; the PIAMA study

Abstract

Aims: To evaluate ethnic differences in the prevalence of respiratory and skin symptoms in the first two years of life.

Methods: A total of 4146 children participated in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study. Parents completed questionnaires on respiratory and skin symptoms, ethnic background, and other potential confounders during pregnancy, and at 3 months, 1 year, and 2 years of age.

Results: In the first year, "non-Dutch" children (compared with "Dutch" children) had a higher prevalence of runny nose with itchy/watery eyes (11.0% versus 5.0%). In the second year, a higher prevalence of wheeze at least once (26.7% versus 18.5%), night cough without a cold (24.6% versus 15.5%), runny nose without a cold (34.1% versus 21.3%), and runny nose with itchy/watery eyes (13.7% versus 4.6%) was found. Adjustment for various confounders, especially adjustment for socioeconomic factors, reduced most associations between ethnicity and respiratory symptoms. Only runny nose with itchy/watery eyes in the second year of life was independently associated with non-Dutch ethnicity (adjusted odds ratio 2.89, 95% CI 1.3-6.4).

Conclusions: Non-Dutch children more often had respiratory symptoms in the first two years of life than Dutch children. This could largely be explained by differences in socioeconomic status. Follow up of the cohort will determine whether this higher prevalence of respiratory symptoms in children with non-Dutch ethnicity represents an increased risk of developing allergic disease rather than non-specific or infection related respiratory symptoms.

Figure 1

(A) Prevalence of respiratory and skin symptoms in the first year of life, stratified for ethnic background. (B) Prevalence of respiratory symptoms in the second year of life, stratified for ethnic background. Error bars represent 95% CI. *p = 0.01; †p = 0.02; ‡p = 0.001; ¶p < 0.001, all χ².

Figure 2

cOR and aOR (horizontal bars) and 95% CI (vertical lines) for the association between non-Dutch ethnicity and the development of respiratory symptoms in the first two years of life, using Dutch children as the reference group. *Model 1, crude odds ratios. †Model 2, adjusted for gender, allergic family history, day care, birth weight, smoke exposure in the home at age 1, type of feeding at 3 months of age, and study type (natural history, intervention active, intervention placebo). ‡Model 3, as in model 1, but also adjusted for maternal age, parental employment, and maternal education.