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15-04-2010 | Respiratory | Article

Protective effect of farming environment against asthma supported


Free abstract

MedWire News: Growing up in a farming environment is associated with a reduced risk for asthma in teenagers and young adults, results from a Swedish study confirm.

Writing in the journal Pediatric Allergy and Immunology, Göran Wennergren (University of Gothenburg) and team explain: “The prevalence of and the risk factors for asthma in childhood have been studied extensively.

“In contrast, the data for the transitional period from childhood to adulthood are less abundant.”

To investigate further, and to analyze whether the prevalence of asthma is still increasing among young people, the researchers studied data from a postal questionnaire completed by 1261 individuals (701 females), aged 16–20 years, living in Gothenburg and the surrounding region of western Sweden.

Overall, 9.5% of respondents reported a diagnosis of asthma, while 9.6% reported that they used asthma medications.

This prevalence of diagnosed asthma is similar to the reported prevalence of 8–10% among this age group during the mid-1990s, the researchers note.

Multivariate analysis showed that the strongest risk factors for doctor-diagnosed asthma were a family history of asthma (odds ratio [OR]=1.9) and allergy (OR=1.9), with an even greater risk for the respiratory condition if both these risk factors occurred together (OR=4.3).

The researchers also found that growing up on a farm significantly reduced the risk for asthma (OR=0.1) compared with growing up in an urban environment, supporting the results from previous studies.

Being an ex-smoker increased the risk for doctor-diagnosed asthma (OR=2.6), while current smoking was associated with an increased risk for recurrent wheeze (OR=1.6), long-standing cough (OR=3.4), and sputum production (OR=2.8).

Wennergren and team conclude: “The prevalence of physician-diagnosed asthma and the use of asthma medication in the 16- to 20-year age group support the notion that the increase in asthma prevalence seen between the 1950s and the 1990s has now leveled off.

“In line with the hygiene hypothesis, a farm childhood significantly reduced the likelihood of asthma.”

They add: “The indices of adverse effects of smoking could already be seen at this young age.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Mark Cowen

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