TY - JOUR
T1 - The Urban-Rural Gradient In Asthma
T2 - A Population-Based Study in Northern Europe
AU - Timm, Signe
AU - Frydenberg, Morten
AU - Janson, Christer
AU - Campbell, Brittany
AU - Forsberg, Bertil
AU - Gislason, Thorarinn
AU - Holm, Mathias
AU - Jogi, Rain
AU - Omenaas, Ernst
AU - Sigsgaard, Torben
AU - Svanes, Cecilie
AU - Schlünssen, Vivi
PY - 2016
Y1 - 2016
N2 - The early life environment appears to have a persistent impact on asthma risk. We hypothesize that environmental factors related to rural life mediate lower asthma prevalence in rural populations, and aimed to investigate an urban-rural gradient, assessed by place of upbringing, for asthma. The population-based Respiratory Health In Northern Europe (RHINE) study includes subjects from Denmark, Norway, Sweden, Iceland and Estonia born 1945–1973. The present analysis encompasses questionnaire data on 11,123 RHINE subjects. Six categories of place of upbringing were defined: farm with livestock, farm without livestock, village in rural area, small town, city suburb and inner city. The association of place of upbringing with asthma onset was analysed with Cox regression adjusted for relevant confounders. Subjects growing up on livestock farms had less asthma (8%) than subjects growing up in inner cities (11%) (hazard ratio 0.72 95% CI 0.57–0.91), and a significant urban-rural gradient was observed across six urbanisation levels (p = 0.02). An urban-rural gradient was only evident among women, smokers and for late-onset asthma. Analyses on wheeze and place of upbringing revealed similar results. In conclusion, this study suggests a protective effect of livestock farm upbringing on asthma development and an urban-rural gradient in a Northern European population.
AB - The early life environment appears to have a persistent impact on asthma risk. We hypothesize that environmental factors related to rural life mediate lower asthma prevalence in rural populations, and aimed to investigate an urban-rural gradient, assessed by place of upbringing, for asthma. The population-based Respiratory Health In Northern Europe (RHINE) study includes subjects from Denmark, Norway, Sweden, Iceland and Estonia born 1945–1973. The present analysis encompasses questionnaire data on 11,123 RHINE subjects. Six categories of place of upbringing were defined: farm with livestock, farm without livestock, village in rural area, small town, city suburb and inner city. The association of place of upbringing with asthma onset was analysed with Cox regression adjusted for relevant confounders. Subjects growing up on livestock farms had less asthma (8%) than subjects growing up in inner cities (11%) (hazard ratio 0.72 95% CI 0.57–0.91), and a significant urban-rural gradient was observed across six urbanisation levels (p = 0.02). An urban-rural gradient was only evident among women, smokers and for late-onset asthma. Analyses on wheeze and place of upbringing revealed similar results. In conclusion, this study suggests a protective effect of livestock farm upbringing on asthma development and an urban-rural gradient in a Northern European population.
KW - RHINE
KW - asthma
KW - early life environment
KW - farming
KW - hygiene hypothesis
KW - microbial exposure
KW - urban-rural gradient
UR - http://www.scopus.com/inward/record.url?scp=84952802008&partnerID=8YFLogxK
U2 - 10.3390/ijerph13010093
DO - 10.3390/ijerph13010093
M3 - Journal article
C2 - 26729146
SN - 1661-7827
VL - 13
JO - International Journal of Environmental Research and Public Health
JF - International Journal of Environmental Research and Public Health
IS - 1
M1 - 93
ER -