Public Health Wales / Primary and secondary prevention of
asthma
Healthcare Service Improvement Team
Primary and secondary prevention of asthma
Author: Norma Prosser, Dr Mary Webb, Public Health Specialists
Date: 3 September 2010 / Version: 1
Publication/ Distribution:
·  Public (Internet)
Review Date: A review of this document is not planned by Public Health Wales NHS Trust
Purpose and Summary of Document:
This is an evidence-based summary of effective interventions for primary and secondary prevention of asthma. It has been produced to assist local health boards to implement Designed for people with chronic conditions, Service development and commissioning directives, Chronic respiratory conditions, and should be read in conjunction with that publication.
Interventions are aimed at known risk factors and avoidance measures that include tobacco smoke and allergens.
Work Plan reference: HS04
Date: 3 Sep 2010 / Version: 1 / Page: 2 of 10
Public Health Wales / Primary and secondary prevention of
asthma


CONTENTS

1 Background 3

2 Asthma 3

2.1 Introduction 3

2.2 Search methodology 3

2.3 Prevalence 3

2.4 Hospital admissions 3

3 Primary prevention 3

4 Secondary prevention 3

5 Further information 3

6 References 3

© 2010 Public Health Wales NHS Trust.

Material contained in this document may be reproduced without prior permission provided it is done so accurately and is not used in a misleading context.

Acknowledgement to Public Health Wales NHS Trust to be stated.

1  Background

This document has been produced to assist local health boards to implement the Welsh Assembly Government’s, Designed for people with chronic condition, Service development and commissioning directives, Chronic respiratory conditions1, and should be read in conjunction with that publication.

A key action identified in chapter 2: Prevention – reducing the risks (p. 22) of the publication is evidence-based primary and secondary prevention1.

To supplement the evidence–base, and provide an overview of the topic, information with regard to prevalence (where available); hospital admissions (where information is available from Patient Episode Database Wales - PEDW); and links to additional information resources have been included. The links to the additional information resources is included to indicate where further details, or management and treatment guidance can be sought.

The information contained in this document is not exhaustive.

2  Asthma

2.1  Introduction

Asthma is a disorder defined by its clinical, physiological and pathological characteristics. An operational description of asthma is described by the Global Initiative for Asthma (GINA)2 as a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. The chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing, particularly at night or in the early morning. These episodes are usually associated with widespread, but variable, airflow obstruction within the lung that is often reversible either spontaneously or with treatment.

2.2  Search methodology

Search terms used: primary prevention, secondary prevention, asthma.

Search terms were kept broad to maximise retrieval of literature and search limits set to retrieve papers published between January 2003 to January 2010.

Electronic databases: Medline; Embase; Cochrane Database of Systematic Reviews; Database of Abstracts of Reviews of Effects; Cochrane Central Register of Controlled Trials and British Nursing Index.

Meta search engines: Turning Research Into Practice (TRIP); Google Scholar; SUMsearch.

Websites: NHS Evidence; International Network of Agencies for Health Technology Assessment (INAHTA); National Institute for Health and Clinical Excellence (NICE); National Horizon Scanning Centre and Map of Medicine; UpToDate.

2.3  Prevalence

Between 1964 and 1989 the proportion of children in the United Kingdom (UK) in whom asthma was diagnosed increased from 4% to 10%, and a rise in the prevalence of asthmatic symptoms was indicated between 1988 and 20033. In contrast, self-reported symptoms of asthma in children 13–14 years of age decreased approximately 20% in the UK between 1995 and 20023.

In early childhood, asthma is more common in boys than in girls, but by adulthood the sex ratio is reversed, the reason for this is not clear3. In the UK approximately 60% of adults with asthma are women3.

Each year, a GP with 2000 patients will see approximately 85 people with asthma, and each of these will consult three times on average3. Occupational asthma may account for 9–15% of adult-onset asthma and it is considered to be the most common industrial lung disease in the developed world3.

Asthma prevalence in Wales is reported to be one of the highest in the world. Asthma UK Cymru findings suggest there are 260,000 people living with asthma in Wales, 205,000 adults and 55,000 children, which equates to 1 in 10 children and 1 in 12 adults currently being treated for doctor-diagnosed asthma4. The findings from the Welsh Health Survey (2008) state that 10% of adults reported that they were currently being treated for asthma5 (approximately 244,000 adults6).

Wales has 4,000 hospital admissions for asthma a year, in the case of adults; a rate nearly 30% higher than the rest of the UK, and of these hospital admissions, 75% could have been avoided4. Asthma deaths in Wales are more common than anywhere else in the UK4. Asthma is a condition that most people should be able to control, with modern asthma treatments 75% of hospital admissions and 90% of asthma deaths are preventable4.

The cost of asthma to the UK economy as a whole is £2.3 billion and the cost to the NHS across the UK is £889 million7.

The likelihood of development or persistence of asthma may be attributed to:- 2, 8

·  allergens:

o  indoor e.g. mites, pets, moulds, fungi;

o  outdoor e.g. pollens, fungi;

·  co-existence of atopic disease;

·  diet;

·  family history of atopic disease e.g. asthma, eczema, allergic rhinitis, or allergic conjunctivitis;

·  male sex for pre-pubertal asthma and female sex for persistence of asthma from childhood to adulthood;

·  bronchiolitis in infancy;

·  obesity;

·  occupational sensitizers;

·  parental smoking, including perinatal exposure to tobacco smoke;

·  low birthweight associated with intrauterine growth retardation;

·  premature birth especially in extreme-preterm infants who required ventilatory support, with consequent chronic lung disease of prematurity;

·  viral infections.

2.4  Hospital admissions

Figure 1: Persons admitted to hospital in Wales in 2008 with a principal diagnosis of asthma (ICD-10, J45 & J46) by Unitary Authority

Source: PEDW

Figure 2: Persons admitted to hospital in Wales in 2008 with a principal diagnosis of asthma (ICD-10, J45 & J46) by Local Health Board

Source: PEDW

Table 1: Persons admitted to hospital in Wales in 2008 with a principal diagnosis of asthma (ICD-10, J45 & J46)

Local Health Board / Unitary Authority / Admissions
Betsi Cadwaladr University / Isle of Anglesey / 84
Gwynedd / 119
Conwy / 120
Denbighshire / 111
Flintshire / 187
Wrexham / 175
Powys / Powys / 119
Hywel Dda / Ceredigion / 61
Pembrokeshire / 149
Carmarthenshire / 199
Abertawe Bro Morgannwg / Swansea / 393
Neath Port Talbot / 282
Bridgend / 200
Cardiff and Vale University / Vale of Glamorgan / 181
Cardiff / 385
Cwm Taf / Rhondda Cynon Taff / 257
Merthyr Tydfil / 67
Aneurin Bevan / Caerphilly / 212
Blaenau Gwent / 111
Torfaen / 158
Monmouthshire / 90
Newport / 226
Total / 3886

Source: PEDW

3  Primary prevention

Primary prevention interventions are aimed at the known risk factors for asthma and avoidance measures2, 8.

The evidence for primary interventional strategies is based predominantly on observational studies, though some have been tested using experimental methods8. Primary prevention of asthma is based on8:-

·  allergen avoidance;

·  breastfeeding;

·  modified milk formulae;

·  nutritional supplements;

·  immunotherapy;

·  microbial exposure;

·  avoidance of tobacco smoke;

·  dietary manipulation: fish oil and fatty acids; electrolytes; weight reduction.

In determining the evidence for primary prevention, the British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network (SIGN) guidelines8 makes recommendations for breast feeding, avoidance of tobacco smoke and weight reductions, for all other interventions there was insufficient evidence.

A Cochrane review9, not included in the BTS/SIGN guidelines, suggests that in children who are at risk of developing childhood asthma, multifaceted interventions characterised by dietary allergen reduction and environmental remediation, reduce the odds of a physician diagnosis of asthma later in childhood by half. This translates to a number needed to treat (NNT) of 17.

There is a common perception amongst patients and carers that there are numerous environmental, dietary and other triggers of asthma and that avoiding these triggers will improve asthma and reduce the requirement for pharmacotherapy8.

4  Secondary prevention

Secondary prevention is based on interventions to address2, 8:-

·  air pollution;

·  house dust mites;

·  pets;

·  smoking;

·  immunotherapy.

The BTS/SIGN guideline8 recommends interventions targeting smoking and immunotherapy and a reduction in exposure to house dust mites.

A Cochrane review10 indicates that asthma education aimed at children and their carers who present to the emergency department for acute exacerbations can result in lower risk of future emergency department presentation and hospital admission. There remains uncertainty as to the long-term effect of education on other markers of asthma morbidity such as quality of life, symptoms and lung function. It remains unclear as to what type, duration and intensity of educational packages are the most effective in reducing acute care utilisation.

A BTS statement on criteria for specialist referral, admission, discharge and follow-up for adults with respiratory disease proposes good practice indicators in the management of respiratory disease for adults; asthma is included in the disease specific statement11.

5  Further information

British Lung Foundation

·  Asthma

http://www.lunguk.org/

British Thoracic Society:

·  Standards of Care Committee: BTS statement on criteria for specialist referral, admission, discharge and follow-up for adults with respiratory disease

http://www.brit-thoracic.org.uk/Portals/0/Clinical%20Information/Good%20Clinical%20Practice/hospreferalthorax.pdf

British Thoracic Society (BTS): Scottish Intercollegiate Guidelines Network (SIGN):

·  British guideline on the management of asthma;

·  Standards of care for occupational asthma.

http://www.brit-thoracic.org.uk/library-guidelines.aspx

Map of medicine:

·  Asthma in children:

o  Acute asthma in children – suspected;

o  Acute asthma exacerbation in children (primary care);

o  Acute asthma in children (emergency department management of severe exacerbation);

o  Acute asthma in children (secondary care inpatient management);

o  Management of chronic asthma in children – review and assessment of management step;

o  Management of chronic asthma in children – regular asthma preventer therapy (step 2);

o  Management of chronic asthma in children – add on therapy (step 3);

o  Management of chronic asthma in children – persistent poor control (step 4).

·  Acute asthma:

o  Acute asthma suspected:

o  Acute asthma – primary care assessment;

o  Acute asthma – primary care management;

o  Acute asthma – secondary care management;

o  Life threatening acute asthma management.

·  Chronic asthma:

o  Chronic asthma –suspected;

o  Management of established asthma;

o  Management of asthma step 2;

o  Management of asthma – step 3;

o  Management of persistent poorly controlled asthma – steps 4 and 5.

http://nhsevidence.mapofmedicine.com/evidence/map/index.html

6  References

  1. Welsh Assembly Government. Designed for people with chronic condition. Service development and commissioning directives. Chronic respiratory conditions. Cardiff: WAG; 2007. Available at: http://wales.gov.uk/dhss/publications/health/strategies/chronicrespiratory/respiratorye.pdf;jsessionid=2T6fLNkJTBJcQ0ZzBLgcJfCjsXtmc0K0JKQvB4X1JnQp1hHbqZsG!-330498905?lang=en [Accessed 11th Mar 2010]
  1. Global Initiative for Asthma. [Website]. Global strategy for asthma management and prevention. GINA; 2009. Available at: http://www.ginasthma.com/Guidelineitem.asp??l1=2&l2=1&intId=1561 [Accessed 11th Mar 2010]
  1. NHS Clinical Knowledge summaries. [Website]. Asthma. 2009. Available at: http://www.cks.nhs.uk/asthma#297035001 [Accessed 11th Mar 2010]
  1. Asthma UK. A quarter of a million voices: asthma in Wales today. London: Asthma UK; 2005. Available at: http://www.asthma.org.uk/all_about_asthma/publications/a_quarter_of_a_milli.html [Accessed 11th Mar 2010]
  1. Welsh Assembly Government. Statistics for Wales: Welsh health survey 2008. Cardiff: WAG; 2008. Available at: http://wales.gov.uk/docs/statistics/2009/090929hlthsurvey08en.pdf [Accessed 21st Apr 2010]
  1. Welsh Assembly Government. Statistics bulletin: 2008 mid-year estimates of population. SB 49/2009. Cardiff: WAG; 2009. Available at:

http://wales.gov.uk/docs/statistics/2009/090827sb492009en.pdf

[Accessed 21st Apr 2010]

  1. Asthma UK. Where do we stand? Asthma in the UK today. London: Asthma UK; 2004. Available at: http://www.asthma.org.uk/health_professionals/ordering_materials/where_do_we_stand.html [Accessed 11th Mar 2010]
  1. British Thoracic Society, Scottish Intercollegiate Guidelines Network. British guideline on the management of asthma. A national clinical guideline. No. 101. Edinburgh: SIGN; 2009. Available at: http://www.sign.ac.uk/pdf/sign101.pdf [Accessed 11th Mar 2010]
  1. Maas T et al. Mono and multifaceted inhalant and/or food allergen reduction interventions for preventing asthma in children at high risk of developing asthma. Cochrane Database Syst Rev 2009, Issue 3. Art. No.: CD006480. DOI: 10.1002/14651858.CD006480.pub2. Available at: http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD006480/pdf_fs.html [Accessed 12th Mar 2010]
  2. Boyd M et al. Interventions for educating children who are at risk of asthma-related emergency department attendance. Cochrane Database Syst Rev 2009, Issue 2. Art. No.: CD001290. DOI: 10.1002/14651858. CD001290.pub2. Available at: http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD001290/pdf_fs.html [Accessed 12th Mar 2010]
  1. British Thoracic Society Standards of Care Committee. BTS statement on criteria for specialist referral, admission, discharge and follow-up for adults with respiratory disease. Thorax 2008; 63(Suppl I):i1–i16. doi:10.1136/thx.2007.087627. Available at: http://www.brit-thoracic.org.uk/Portals/0/Clinical%20Information/Good%20Clinical%20Practice/hospreferalthorax.pdf [Accessed 19th Apr 2010]

Date: 3 Sep 2010 / Version: 1 / Page: 2 of 10