Asthma, Rhinitis, Other Respiratory Diseases
Asthma prevalence and morbidity among rural Iowa schoolchildren

https://doi.org/10.1016/j.jaci.2003.09.037Get rights and content

Abstract

Background

There are conflicting findings about the prevalence of asthma among farm and nonfarm children.

Objectives

We sought to estimate asthma prevalence and morbidity and determine differences between farm and nonfarm children.

Methods

The study population consisted of all children aged 6 to 14 years enrolled in 10 school districts in 2 noncontiguous rural Iowa counties from 2000 through 2002. The mailed parental screening questionnaire included the International Study of Asthma and Allergies in Childhood core questionnaire, items from the Functional Severity Index, and items on physician diagnosis and medication and urgent care use.

Results

The response rate was 86.6%. The 12-month prevalence of wheeze was 19.1%. Self-reported physician diagnosis of asthma was reported by 13.4%. On multivariable analysis controlling for age, sex, and county, children who lived on farms were less likely than those who lived in town to have ever wheezed (odds ratio, 0.71; 95% CI, 0.58-0.87) or to have wheezed during the past year (odds ratio, 0.77; 95% CI, 0.60-0.98). However, this protective association with farming was only observed in one of the study counties. Among those who wheezed, farm and nonfarm children were equally likely to have been given a diagnosis of asthma and had comparable morbidity.

Conclusion

By using a standardized questionnaire with a high response rate in this large, rural, population-based study, asthma prevalence rivaled that in large Midwestern cities. Unmeasured risk factors might account for the apparent protective effect in Keokuk County. These findings cast doubt on a protective effect of rural life for the development of childhood asthma.

Section snippets

Methods

The study was approved by the Institutional Review Board of the University of Iowa. The study sample was all children aged 6 to 14 years who were enrolled in one of 10 school districts in either of 2 noncontiguous rural Iowa counties during the academic years 1999-2000, 2000-2001, and 2001-2002. The 2 counties were selected because of their close similarity in agricultural production. Screening was conducted during 3 separate time periods, each consisting of approximately equal numbers of

Results

The study population is described in Table I. The lifetime prevalence of wheeze was 30.9%. Wheezing in the past year was reported by 19.1%. A physician diagnosis of asthma was reported by 13.4%. Among those who had ever wheezed, more than a third reported frequent symptoms, and 15.3% reported severe symptoms in the past year.

Multivariable analyses are displayed in Table II. Results of stratified analyses and tests for county by residence–type interactions (P values between .07 and .26)

Discussion

A high response rate was obtained in this large, rural, population-based study using an internationally standardized instrument for measuring the prevalence of wheeze and asthma. We found a prevalence of wheeze or asthma comparable with that seen in Midwestern cities, thus casting doubt on a protective effect of rural living for the development of asthma. Comparing our results with those of other studies that used the ISAAC questionnaire, the 12-month prevalence of wheeze (19.1%) was comparable

Acknowledgments

We acknowledge the advice and collaboration of the following asthma subcommittee members in the 2 counties: Rob Baker, Tadd Davis, Valerie Hammes, David Harris, Linda Northup, Mary Beth Adams, Sharon DellaVedova, Linda Grande, Chris McFarland, Thomas O'Toole, and Scott Rollinger. Study research staff collected and entered the data and were responsible for achieving the questionnaire response rate: Ruth Walker, Linda Harris, and Avis Hill.

We acknowledge the guidance and cooperation of numerous

References (24)

  • M Kogevinas et al.

    Occupational asthma in Europe and other industrialized areas: a population-based study. European Community Respiratory health Survey Study Group

    Lancet

    (1999)
  • J Riedler et al.

    Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey

    Lancet

    (2001)
  • MI Asher et al.

    The International Study of Asthma and Allergies in Childhood (ISAAC)

    Clin Exp Allergy

    (1998)
  • The International study of Asthma and Allergies in Childhood (ISAAC) Steering Committee

    Worldwide variations in the prevalence of asthma symptoms: the International Study of Asthma and Allergies in Childhood (ISAAC)

    Eur Respir J

    (1998)
  • C Braun-Fahrlander et al.

    Prevalence of hay fever and allergic sensitization in farmer's children and their peers living in the same rural community-SCARPOL Team. Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution

    Clin Exp Allergy

    (1999)
  • P Ernst et al.

    Relative scarcity of asthma and atopy among rural adolescents raised on a farm

    Am J Respir Crit Care Med

    (2000)
  • American Thoracic Society

    Respiratory health hazards in agriculture

    Am J Respir Crit Care Med

    (1998)
  • J Douwes et al.

    Biological agents recognition

  • BP Yawn et al.

    Do rural and urban children have comparable asthma care utilization?

    J Rural Health

    (2001)
  • S Tong et al.

    Hospital admission and mortality differentials of asthma between urban and rural populations in New South Wales

    Aust J Rural Health

    (1999)
  • JK Williams et al.

    School nurses' experiences with children with chronic conditions

    J School Health

    (1995)
  • Cited by (0)

    Supported by a grant jointly funded by the NIEHS (ES09607) and the EPA (R826711). The authors also acknowledge support from the University of Iowa, Environmental Health Sciences Research Center (NIEHS P30-ES05605).

    View full text