Trends in the prevalence of asthma, rhinitis, and eczema in 15 year old adolescents over an 8 year period.
BACKGROUND
Trends in prevalence of asthma and allergic diseases are still controversial, and rarely studied among adolescents at midpoint of puberty.


METHODS
In 2000, a questionnaire was mailed to adolescents (n = 18,158) attending 9th grade at school and living in Västra Götaland County, Sweden. Eight years later, the same questionnaire was mailed to adolescents (n = 21,651), using identical inclusion criteria as previously. Altogether, 10,837 adolescents completed the questionnaire in 2000 and 11,754 in 2008. Differences in prevalence of physician diagnosed asthma, asthma symptoms, rhinitis, and eczema between the periods were analyzed by Chi-square test. Multiple logistic regression models were performed to test for trends in prevalence of these diseases, adjusting for potential confounders.


RESULTS
Physician diagnosed asthma and lifetime and current rhinitis were increased in 2008, while wheeze decreased (p < 0.05). Taking sex, foreign descent, body mass index, and parents' education into account, the prevalence of physician diagnosed asthma (OR 1.3 [95% CI 1.2-1.4]) and lifetime (1.7 [1.6-1.8]) and current rhinitis (1.5 [1.4-1.6]) had increased. Eczema had decreased (0.9 [0.8-0.98]). These trends were consistent in boys and girls, but more prominent in those with obesity. In physician diagnosed asthmatics, there was no change in wheeze, asthma symptoms, or asthma medication.


CONCLUSIONS
The prevalence of physician diagnosed asthma has increased over the last decade, maybe due to combinations of changes in diagnostics and increased general awareness, rather than a real increase. Results showed an increase in rhinitis and a decrease in eczema. Obesity seems to have a modifying effect, which calls for further investigation.
Section of Occupational and Environmental Medicine, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Electronic address: jeong-lim.kim@amm.gu.se.
Jeong-Lim
JL
Kim
Section of Occupational and Environmental Medicine, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Jonas
J
Brisman
Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden; Department of Primary Health Care, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Maria Al
MA
Aberg
Department of Internal Medicine and Clinical Nutrition, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Heléne Bertéus
HB
Forslund
Department of Internal Medicine and Clinical Nutrition, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Anna
A
Winkvist
Section of Occupational and Environmental Medicine, Institute of Medicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Section of Occupational Medicine, Respiratory Diseases and Toxicology, University of Perugia, Perugia, Italy.
Kjell
K
Torén
D000293:Adolescent; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004485:Eczema / Q000453:epidemiology* / Q000209:etiology; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications / Q000453:epidemiology; D010290:Parents; D015995:Prevalence; D012220:Rhinitis / Q000453:epidemiology* / Q000209:etiology; D013548:Sweden
Asthma medication; Awareness; Diagnostic practices; Education; ISO-body mass index (ISO-BMI); Obesity