Synergism between allergens and viruses and risk of hospital admission with asthma: case-control study

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http://bmj.com/cgi/content/abstract/324/7340/763

BMJ 2002;324:763 ( 30 March )

Papers

Synergism between allergens and viruses and risk of hospital admission with

asthma: case-control study

lind M Green, research registrar, a Adnan Custovic, National Asthma

Campaign senior clinical research fellow, a Gwen on, research

technician, b Hunter, research technician, c Sebastian L ston,

professor, b Woodcock, professor. a

a North West Lung Centre, Wythenshawe Hospital, Manchester M23 9LT, b

Department of Respiratory Medicine, National Heart and Lung Institute

Faculty of Medicine, Imperial College of Science, Technology and Medicine,

London W2 1PG, c University Medicine, Southampton General Hospital,

Southampton SO9 6YD

Correspondence to: A Custovic acustovic@...

Objective: To investigate the importance of sensitisation and exposure to

allergens and viral infection in precipitating acute asthma in adults

resulting in admission to hospital.

Design: Case-control study.

Setting: Large district general hospital.

Participants: 60 patients aged 17-50 admitted to hospital over a year with

acute asthma, matched with two controls: patients with stable asthma

recruited from the outpatient department and patients admitted to hospital

with non-respiratory conditions (inpatient controls).

Main outcome measures: Atopic status (skin testing and total and specific

IgE), presence of common respiratory viruses and atypical bacteria

(polymerase chain reaction), dust samples from homes, and exposure to

allergens (enzyme linked immunosorbent assay (ELISA): Der p 1, Fel d 1, Can

f 1, and Bla g 2).

Results: Viruses were detected in 31 of 177 patients. The difference in the

frequency of viruses detected between the groups was significant (admitted

with asthma 26%, stable asthma 18%, inpatient controls 9%; P=0.04). A

significantly higher proportion of patients admitted with asthma (66%) were

sensitised and exposed to either mite, cat, or dog allergen than patients

with stable asthma (37%) and inpatient controls (15%; P<0.001). Being

sensitised and exposed to allergens was an independent associate of the

group admitted to hospital (odds ratio 2.3, 95% confidence interval 1.0 to

5.4; P=0.05), whereas the combination of sensitisation, high exposure to one

or more allergens, and viral detection considerably increased the risk of

being admitted with asthma (8.4, 2.1 to 32.8; P=0.002).

Conclusions: Allergens and viruses may act together to exacerbate asthma.

What is already known on this topic

Studies on segmental allergen challenge of the lung and experimental

rhinovirus infection show synergistic effects between allergens and

respiratory virus infection

No studies have investigated an interaction between sensitisation, exposure

to allergens, and virus infections in real life exacerbations of asthma

What this study adds

Allergens and viruses may act together to exacerbate asthma, indicating that

domestic exposure to allergens acts synergistically with viruses in

sensitised patients, increasing the risk of hospital admission

Strategies to reduce the impact of asthma exacerbations in adults should

include interventions directed at both viruses and reducing exposure to

allergens

© BMJ 2002

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bherk@... wrote: http://bmj.com/cgi/content/abstract/324/7340/763BMJ 2002;324:763 ( 30 March )PapersSynergism between allergens and viruses and risk of hospital admission withasthma: case-control studylind M Green, research registrar, a Adnan Custovic, National AsthmaCampaign senior clinical research fellow, a Gwen on, researchtechnician, b Hunter, research technician, c Sebastian L ston,professor, b Woodcock, professor. aa North West Lung Centre, Wythenshawe Hospital, Manchester M23 9LT, bDepartment of Respiratory Medicine, National Heart and Lung InstituteFaculty of Medicine, Imperial College of Science, Technology and Medicine,London W2 1PG, c University Medicine, Southampton General Hospital,Southampton SO9 6YDCorrespondence to: A Custovic acustovic@...Objective: To investigate the importance of sensitisation and exposure toallergens and viral infection in precipitating acute asthma in adultsresulting in admission to hospital.Design: Case-control study.Setting: Large district general hospital.Participants: 60 patients aged 17-50 admitted to hospital over a year withacute asthma, matched with two controls: patients with stable asthmarecruited from the outpatient department and patients admitted to hospitalwith non-respiratory conditions (inpatient controls).Main outcome measures: Atopic status (skin testing and total and specificIgE), presence of common respiratory viruses and atypical bacteria(polymerase chain reaction), dust samples from homes, and exposure toallergens (enzyme linked immunosorbent assay (ELISA): Der p 1, Fel d 1, Canf 1, and Bla g 2).Results: Viruses were detected in 31 of 177 patients. The difference in thefrequency of viruses detected between the groups was significant (admittedwith asthma 26%, stable asthma 18%, inpatient controls 9%; P=0.04). Asignificantly higher proportion of patients admitted with asthma (66%) weresensitised and exposed to either mite, cat, or dog allergen than patientswith stable asthma (37%) and inpatient controls (15%; P<0.001). Beingsensitised and exposed to allergens was an independent associate of thegroup admitted to hospital (odds ratio 2.3, 95% confidence interval 1.0 to5.4; P=0.05), whereas the combination of sensitisation, high exposure to oneor more allergens, and viral detection considerably increased the risk ofbeing admitted with asthma (8.4, 2.1 to 32.8; P=0.002).Conclusions: Allergens and viruses may act together to exacerbate asthma.What is already known on this topicStudies on segmental allergen challenge of the lung and experimentalrhinovirus infection show synergistic effects between allergens andrespiratory virus infectionNo studies have investigated an interaction between sensitisation, exposureto allergens, and virus infections in real life exacerbations of asthmaWhat this study addsAllergens and viruses may act together to exacerbate asthma, indicating thatdomestic exposure to allergens acts synergistically with viruses insensitised patients, increasing the risk of hospital admissionStrategies to reduce the impact of asthma exacerbations in adults shouldinclude interventions directed at both viruses and reducing exposure toallergens© BMJ 2002FAIR USE NOTICE:This site contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner.