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PACT Centre Pages - PRESCRIBING OF DRUGS FOR ASTHMA AND COPD

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graph 1
Trends in Prescribing of Drugs for Asthma and COPD in England (Chart 1)

Asthma and chronic obstructive pulmonary disease (COPD) are the most common major respiratory diseases. About 10% of the population experience asthma, however its prevalence varies between different age groups and the proportion of children who wheeze is higher than 10%. COPD, which is usually a disease of the middle aged and elderly, is less prevalent than asthma. However many more people die from COPD than from asthma.


Prescribing of drugs for asthma and COPD shows a seasonal variation (Chart 1) with more prescriptions from October to December. Over the last 5 years prescribing of these drugs has risen slightly. Total cost has also increased (Chart 2), which is mainly due to increased spending on newer drugs such as fluticasone, eformoterol and salmeterol. The cost of most of
the older drugs has fallen.

The British Thoracic Society (BTS) published guidelines for asthma and for COPD in 19971,2. These guidelines cover diagnosis as well as treatment. Distinguishing between asthma and COPD can be difficult in older people. In COPD the airways obstruction is mainly irreversible and does not change markedly over time whereas in asthma the airflow obstruction is variable and can fluctuate markedly in a few hours. Some patients with COPD do show reversible airways obstruction if given a bronchodilator. Spirometric tests should be used in patients with COPD to confirm the diagnosis and to plan appropriate treatment. Reversibility testing with an inhaled short acting beta agonist can help to rule out asthma.2

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graph 2
Trends in Spending on Drugs for Asthma and COPD in England (Chart 2)

Asthma
The BTS Guidelines on the Treatment of Asthma are currently being reviewed. They take a stepped approach to managing chronic asthma, e.g. the steps for adults and school children are:

  • Step 1: occasional use of inhaled short acting beta agonists "as required"
  • Step 2: as for step 1 plus either the addition of lower dose inhaled corticosteroid or cromoglycate/nedocromil
  • Step 3: as for step 1 plus either higher dose inhaled corticosteroid or lower dose inhaled corticosteroid plus one of long acting inhaled beta agonist or slow release theophylline or cromoglycate/nedocromil
  • Step 4: as for step 1 plus higher dose inhaled corticosteroid and one or more of long acting inhaled beta agonist or slow release theophylline or cromoglycate/nedocromil
  • Step 5: as for step 4 plus regular prednisolone table
Since the guidelines were published new trial evidence has become available, which helps to clarify some of the choices at particular steps. All inhaled corticosteroids can cause dose-dependent and duration-dependent systemic effects. For beclomethasone, budesonide and fluticasone, the average dose response curve is relatively flat above doses equivalent to 400 micrograms beclomethasone daily, so dose increases tend to produce relatively small improvements in symptoms and lung function3.

If doses of less than 1000 micrograms per day of beclomethasone (or equivalent doses of other corticosteroids) are used the risk of systemic effects is small3. The Committee on Safety of Medicines has advised that the dose of inhaled corticosteroid should be titrated to the lowest dose at which effective control of asthma is maintained. For fluticasone doses above 500 micrograms twice daily should be prescribed only for patients with severe asthma where additional clinical benefit is expected and is demonstrated by either an improvement in pulmonary function and/or in symptom control, or by the ability to reduce oral corticosteroid therapy. A specialist in the management of asthma should initiate such doses. 4

In patients with poorly controlled asthma (step 3 or above), adding a long acting beta agonist to an inhaled corticosteroid improves symptoms and lung function5. Evidence for the benefit of adding a leukotriene receptor antagonist at step 3 is more limited.

Choice of drug therapy in children under 5 years is similar to that for older patients. Randomised controlled trials have shown that inhaled corticosteroids are more effective than theophylline, cromoglycate, or inhaled long acting beta agonists for improving symptoms and lung function in children with asthma. Inhaled corticosteroids do not appear to impair long term growth.6

A variety of inhaler devices for delivering beta agonists and corticosteroids is now available. The most cost-effective device is a pressurised metered dose inhaler (MDI)7,8. All patients need to be educated about how to use their inhaler whichever one is chosen. The National Institute for Clinical Excellence guidance recommends that for children under 5 years with chronic asthma both corticosteroids and bronchodilators should be delivered by a MDI and spacer system, with a facemask where necessary. If this combination is not clinically effective for the child, nebulised therapy may be considered and in the case of children aged 3 to 5 years, a dry powder inhaler (DPI) may also be considered.9 MDIs are the most frequently prescribed delivery device (70% of all beta agonist items and 66% of inhaled corticosteroids), followed by DPIs (14% of beta agonists and 23% of inhaled corticosteroids), and breath-actuated MDIs (10% of items for both groups of drugs).

Chronic Obstructive Pulmonary Disease
The BTS guidelines for COPD use the "COPD Escalator" to summarise the principal components of a management plan. This escalator covers smoking cessation; antibiotics for acute infections; bronchodilator and corticosteroid therapy; and long term oxygen therapy2. Stopping smoking is the single most important way of affecting outcome at all stages. Inhaled short acting beta agonists, inhaled long acting beta agonists, inhaled antimuscarinic bronchodilators and sustained release oral theophylline are all effective at relieving symptoms10. Combination bronchodilator therapy increases forced expiratory volume in 1 second (FEV1) more than single drug therapy10.

The role of inhaled corticosteroids in stable COPD is still uncertain. They do not modify the annual decline in FEV1 but may reduce exacerbations in some patients10. The BTS recommends that inhaled corticosteroids are prescribed for patients who show an objective response to reversibility testing2. About 10-20% of COPD patients show a positive response to this test and this suggests that many COPD patients who are prescribed inhaled corticosteroids will not derive any clinical benefit11. However there are no large clinical trials to show whether withdrawal of inhaled corticosteroids leads to more frequent exacerbations.

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graph 3
Cost For 28 Days Treatment

Long term oxygen therapy for more than 15 hours per day improves survival in patients with COPD and hypoxaemia12. It appears to be most effective in patients with severe hypoxaemia. A respiratory physician should assess all patients considered for long term oxygen therapy2. Prescribing of oxygen cylinders has increased in the last 5 years by 32% to 160,000 items (£2.7 million) for the quarter ending September 2001.

In the last 5 years there has been little overall change in prescribing of selective short acting beta agonists. Salbutamol items have increased by 3% to 3.9 million for the quarter ending September 2001, whilst terbutaline items have decreased by 26% to 0.3 million. Cost has fallen for both. Prescribing of long acting beta agonists has doubled to 550,000 salmeterol items and 75,000 eformoterol items. Salmeterol cost is now higher per quarter (£20.9 million) than salbutamol cost (£19.1 million). Prescribing of antimuscarinic bronchodilators as single preparations has increased by 14% in the last 5 years but cost has not changed. 94% of prescriptions for single antimuscarinic bronchodilators are for ipratropium (437,000 items, £5.5 million for quarter ending September 2001). There has been a large rise (257%) in prescribing of combinations of ipratropium with salbutamol to 293,000 items per quarter, costing £5.3 million. Overall use of aminophylline and theophylline continues to fall steadily. There were 154,000 theophylline items and 145,000 aminophylline items in the quarter ending September 2001. The cost of theophyllines is falling in line with the decrease in prescribing.

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graph 4
Variation Between Health Authorities in Spending on Inhaled Corticosteroids
(Quarter to September 2001) Chart 3
 
In the last 5 years prescribing of inhaled corticosteroids has increased by 11% to 3.0 million items for the quarter ending September 2001. 65% of items are for beclomethasone, 22% fluticasone and 13% budesonide. Prescribing of fluticasone has increased whilst prescribing of the others has decreased slightly. Cost has risen by 26% to £75.6 million. Fluticasone preparations are more expensive than beclomethasone (see price chart) and 41% of inhaled corticosteroid cost is for fluticasone compared to 43% for beclomethasone. Chart 3 shows that there is a 3-fold variation between health authorities in the total cost of inhaled corticosteroids. The percentage spent on fluticasone varies between 23% and 57% with a median of 40%.
There were only 33,000 items in the quarter ending September 2001 for cromoglycate, nedocromil and ketotifen at a cost of £0.9 million. Prescribing of leukotriene receptor antagonists has now reached 96,000 items, £3.1 million for the same quarter.

References

  1. British Thoracic Society. The British guidelines on asthma management: 1995 review and position statement. Thorax 1997; 52 (Suppl 1): S1-S21
  2. The COPD Guidelines Group of the Standards of Care Committee of the BTS. BTS guidelines for the management of chronic obstructive pulmonary disease. Thorax 1997; 52 (Suppl 5): S1-S28
  3. Anonymous. The use of inhaled corticosteroids in adults with asthma. DTB 2000; 38: 5-8
  4. MCA/CSM. Reminder: Fluticasone propionate (Flixotide): use of high doses (>500 micrograms/twice daily).
  5. Cates C, FitzGerald M. Asthma. Clinical Evidence 2001; 5: 1011-1027
  6. Keeley D. Asthma in children. Clinical Evidence 2001; 5: 189-204
  7. Ram FSF et al. Systematic review of clinical effectiveness of pressurised metered dose inhalers versus other hand held inhaler devices for delivering beta 2 agonists bronchodilators in asthma. BMJ 2001; 323: 901-905
  8. Brocklebank D, Wright J, Cates C. Systematic review of clinical effectiveness of pressurised metered dose inhalers versus other hand held inhaler devices for delivering corticosteroids in asthma. BMJ 2001; 323: 896-900
  9. National Institute for Clinical Excellence. Guidance on the use of inhaler systems (devices) in children under the age of 5 years with chronic asthma. Technology Appraisal Guidance No. 10, August 2000
  10. Anonymous. Managing stable chronic obstructive pulmonary disease. DTB 2001; 39: 81-85
  11. National Prescribing Centre. Inhaled corticosteroids: their role in chronic obstructive pulmonary disease. MeReC Bulletin 2000; 11: 21-24
  12. Kerstjens H, Postma D. Chronic obstructive pulmonary disease. Clinical Evidence 2001; 5: 1028-1039

Summary

  • Stopping smoking improves outcome at all stages of COPD

  • The role of corticosteroids in stable COPD is still uncertain

  • In asthma the dose of inhaled corticosteroid should be titrated to the lowest dose at which effective control is maintained

  • Only a specialist in the management of asthma should initiate fluticasone doses above 500 micrograms twice daily

  • Adding a long acting beta agonist to an inhaled corticosteroid improves symptoms and lung function in poorly controlled asthma

  • A pressurised metered dose inhaler is the most cost-effective device for delivering beta agonists or corticosteroids

 
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