ASTHMA

Asthma is a respiratory condition associated with sudden, reversible narrowing of the airways. It is the one of the most common chronic diseases in the UK.

• Airway obstruction in asthma is reversible (spontaneously or with treatment)
• The airways are hyper-responsive to a variety of stimuli
• The bronchi are inflamed.

Symptoms of asthma range from mild to severe, and include:

• Cough
• Wheeze
• Chest tightness
• Breathlessness, and 
• Variable airflow obstruction 

Symptoms are typically variable, intermittent, worse at night and in the early morning, and/or provoked by triggers, eg, allergens, cold air, emotional stress, exercise, chest infection.

Diagnosis

There is no single diagnostic test for asthma. Diagnosis is based on clinical assessment supported by objective tests that demonstrate variable airflow obstruction or the presence of airway inflammation. Diagnostic tests are typically performed at a single point of time, whereas asthma status varies over time. Results of tests taken when a patient is asymptomatic should be compared with those taken when a patient is symptomatic to detect variation over time.

Recommendations between the BTS/SIGN guideline and that from NICE differed in some instances. The British Thoracic Society, Scottish Intercollegiate Guidelines Network and NICE are working together to produce UK-wide guidance on asthm diagnosis and monitoring and chronic asthma amangement that will update and replace NG80. Progress was delayed because of the need to respond to the COVID-19 pandemic, and a revised timetable will be published in due course. 

Spirometry is the investigation of choice for the identification of airflow obstruction. It should be performed by trained healthcare professionals to obtain reliable recordings and to interpret the results. 

In adults with obstructive spirometry, an improvement in FEV1 of 12% or more in response to either β2 agonists or ICS treatment trials, together with an increase in volume of 200ml or more is regarded as a positive test. BTS/SIGN recommend using lower limits of normal to demonstrate airway obstruction. 

Peak expiratory flow monitoring 

• A peak flow recorded when symptomatic (e.g. during the assessment of an asthma attack) may be compared with peak flow when asymptomatic (e.g. after recovery from an attack) to confirm variability

• In adults, serial peak-flow records may demonstrate variability in symptomatic patients but should be interpreted with caution, and in context. There is no evidence to support routine use of peak-flow monitoring in the diagnosis of asthma in children.
• Serial peak flows (at least four readings a day) are the initial investigation of choice in suspected occupational asthma

PEAK EXPIRATORY FLOW (PEF): PAEDIATRIC NORMAL VALUES

For use with EU/EN13826 scale PEF meters only

Peak expratory flow: normal values in children
Height (m)	Predicted EU PEFR (l/min)
0.85	87
0.90	95
0.95	104
1.00	115
1.05	127
1.10	141
1.15	157
1.20	174
1.25	192
1.30	212
1.35	233
1.40	254
1.45	276
1.50	299
1.55	323
1.60	346
1.65	370
1.70	393

 

PEAK EXPIRATORY FLOW (PEF) IN ADULTS: NORMAL VALUES (l/min)
Height	Age (years)
Men
	15	20	25	30	35	40	45	50	55	60	65	70	75	80
135	454	508	541	559	566	563	554	540	523	503	481	458	434	410
140	467	522	557	575	582	579	570	556	538	517	494	471	446	422
145	479	536	571	590	597	594	585	570	551	530	507	483	458	433
150	491	549	585	604	611	609	599	584	565	543	519	495	469	443
155	502	561	598	618	625	622	612	597	578	555	531	506	480	453
160	512	573	611	631	638	636	625	610	590	567	542	516	490	463
165	523	585	623	644	651	648	638	622	602	578	553	527	500	472
170	532	596	635	656	663	660	650	633	613	589	564	537	509	481
175	542	606	646	667	675	672	661	645	624	600	574	546	518	490
180	551	616	656	678	686	683	672	655	634	610	583	555	527	498
185	559	626	667	689	697	694	683	666	644	619	592	564	535	506
190	568	635	677	699	707	707	693	676	654	628	601	572	543	513
195	576	644	686	709	717	714	703	685	663	637	610	580	551	520
Women
135	379	402	414	417	415	409	400	389	376	362	347	332	317	302
140	387	410	422	426	424	417	408	396	383	369	354	339	324	308
145	394	418	430	434	432	425	416	404	391	376	361	346	330	314
150	401	426	438	442	440	433	423	411	398	383	368	352	336	320
155	408	433	445	449	447	440	430	418	404	389	374	358	341	335
160	414	440	452	456	454	447	437	425	411	395	379	363	347	330
165	420	446	459	463	461	454	443	431	417	401	385	368	352	335
170	426	452	465	469	467	460	450	437	442	407	390	374	357	340
175	431	458	471	475	473	566	455	442	428	412	395	378	361	344
180	437	464	477	481	479	472	461	448	433	417	400	383	366	348
185	442	469	483	487	484	477	466	453	438	422	405	387	370	352
190	447	474	488	492	490	482	471	458	443	427	409	392	374	358
195	451	479	493	497	495	487	476	463	448	431	414	396	378	360

Normal values for EU scale peak flow meters; derived from modified Nunn and Gregg values/Miller MR. Airways J 2004; 2/ 2: 80-2.

 

Challenge tests 

Referral for challenge tests (direct or indirect) should be considered in adults with no evidence of airflow obstruction on initial assessment, in whom other objective tests are inconclusive but where asthma remains a possibility 

Fractional exhaled nitric oxide (FeNO)

A positive FeNO tests suggests eosinophilic inflammation and provides supportive but not conclusive evidence for an asthma diagnosis.

FeNO levels are:

• Increased in patients with allergic rhinitis exposed to allergen, even without respiratory symptoms
• Increased by rhinovirus infection in healthy individuals but this effect is inconsistent in people with asthma
• Increased in men, tall people, and by consumption of dietary nitrates
• Lower in children
• Reduced in cigarette smokers
• Reduced by inhaled or oral steroids

In steroid-naïve adults, a FeNO of 40 parts per billion (ppb) or more is regarded as positive; in schoolchildren, a FeNO level of 35 ppb or more is regarded as a positive test.

Structured clinical assessment

Undertake a structured clinical assessment to assess the initial probability of asthma, based on:

• History of recurrent episodes of symptoms, ideally corroborated by variable peak flows when symptomatic and asymptomatic
• Symptoms of wheeze, cough, breathlessness and chest tightness that vary over time
• Recorded observation of wheeze by healthcare professional
• Personal/family history of other atopic conditions
• No symptoms or signs to suggest alternative diagnoses

Probability of asthma 

High probability 

• Record the patient as likely to have asthma, code as suspected asthma, and commence carefully monitored initiation of treatment (typically 6 weeks of ICS)
• Assess baseline status using a validated question (Asthma Control Questionnaire or Asthma Control Test and lung function tests (spirometry or peak expiratory flow)
• At follow-up, assess symptomatic response and lung function
• If response is good (clinically important improvement and/or substantial increase in lung function), confirm diagnosis.
• Adjust treatment according to the response (down-titrate ICS dose) to the lowest dose that maintains the patient free of symptoms.
• Provide self-management education and a personalised asthma action plan (PAAP)
• If objective response is poor or equivocal, discuss adherence, recheck inhaler technique and arrange further tests or consider alternative diagnoses. Usually appropriate to withdraw the treatment.

Low probability 

If there is a low probability of asthma and/or an alternative diagnosis is more likely, investigate for the alternative diagnosis. Reconsider asthma if the clinical picture changes or an alternative diagnosis is not confirmed. Undertake or refer for further tests to investigate for a diagnosis of asthma.

Intermediate probability 

Adults and children who have some but not all of the typical features of asthma or who do not respond well to initial treatment have an intermediate probability of asthma and require further assessment and diagnosis before a diagnosis can be made. Be aware that some conditions can overlap or mimic asthma, including COPD, obesity, anxiety/panic or dysfunction breathing. Spirometry, with bronchodilator reversibility if appropriate, is the preferred initial test for investigating intermediate probability of asthma in adults and in children old enough to produce reliable results.

ASTHMA REVIEW 

The core components of an asthma review that should be assessed and recorded at least annually are current symptoms, future risk of attacks, management strategies, supported self management and growth in children. 

Use a validated asthma control questionnaire or asthma control test to assess current symptom control and to predict the risk of future attacks.

Identifying people with poor symptom control and at future risk of asthma attacks enables targeting of care for the individual patient, by:

• Increasing frequency of review
• Commencing/increasing preventer medication
• Personalisation of an asthma plan
• Avoiding triggers such as smoking
• Shifting the balance of necessity/concerns for ICS treatment

Observe and assess inhaler technique at every review. 

 

Inhaler technique and choice of device 

• Prescribe inhalers only after patients have received training in the use of the device and have demonstrated satisfactory technique.
• In children aged 5-12 and adults, a pMDI + spacer is as effective as any other hand-held inhaler, but some [adult] patients may prefer some types of DPI.
• The choice of device may be determined by the choice of drug

If the patient is unable to use a device satisfactorily an alternative should be found

• The patient should have their ability to use the prescribed inhaler device (particularly for any change in device) checked by a competent healthcare professional
• The medication needs to be titrated against clinical response to ensure optimum efficacy
• Reassess inhaler technique as part of the structured clinical review
• Generic prescribing of inhalers should be avoided as this might lead to people with asthma being given an unfamiliar inhaler device which they are not able to use properly

Asthma UK. Animated interactive demos covering all types of inhaler https://www.asthma.org.uk/advice/inhalers-medicines-treatments/using-inhalers/

PHARMACOLOGICAL MANAGEMENT 

Patients’ inhaler technique is often poor. Selecting an appropriate inhaler device in discussion with the patient, and regularly checking that they are using it correctly, in addition to checking the level of adherence, are key to achieving good asthma control.

SABA 

All patients with symptomatic asthma should be prescribed a short-acting β2 agonist (SABA). Anyone prescribed more than one SABA inhaler device a month should be identified, have their asthma assessed urgently, and measures take to improve asthma control if this is poor.

ICS

Inhaled corticosteroids (ICS) are the recommended preventer drug for adults and children for achieving overall treatment goals: 

• No daytime symptoms
• No night-time awakening due to asthma 
• No need for rescue medication 
• No asthma attacks 
• No limitations on activity, including exercise 
• Normal lung function (in practical terms, FEV1 and/or PEF >80% predicted or best)
• Minimal side effects from medication 

ICS should be considered for adults, children aged 5-12 and children under the age of 5 with any of the following features:

• Using SABA more than three times a week
• Symptomatic three time a week or more
• Waking one night a week

In addition, ICS should be considered in adults and children aged 5-12 who have had an asthma attack requiring oral corticosteroids in the last two years.

Start patients at a dose of ICS appropriate to severity of disease, usually low dose for adults and very low dose for children (refer to summary of product characteristics for individual product). Titrate the dose to the lowest at which effective control of asthma is maintained. High dose ICS should only be used after referring the patient to specialist care. 

There are alternative preventer therapies but these are less effective than ICS.

• Leukotriene receptor antagonists (LTRA) – some beneficial clinical effect. May be used in children under 5 years who are unable to take ICS
• Sodium cromoglicate and nedocromil sodium – of some benefit in adults and effective in children aged 5-12
• Theophyllines – some beneficial effect
• Antihistamines and ketotifen – ineffective 

Initial add-on therapy 

Some patients with asthma may not be adequately controlled with low-dose ICS.

The first choice as add-on therapy to ICS in adults is an inhaled long-acting β2 agonist (LABA), which should be considered before increasing the dose of ICS

In children aged 5 and over, an inhaled LABA or an LTRA can be considered as initial add-on therapy

MART

The use of a single combination inhaler for maintenance and reliever therapy (MART) is an alternative approach to the introduction of a fixed-dose twice-daily combination inhaler. It relies on the rapid onset of reliever effect with formoterol, and by including a dose of ICS ensures that as the need for a reliever increases, the dose of preventer medication is also increased. (A PAAP must be provided with a MART regime).

Combination inhalers are recommended to guarantee that the LABA is not taken without ICS, and to improve inhaler adherence.

If control remains poor on low-dose (adults) or very low-dose (children) ICS plus LABA:

• Re-check diagnosis
• Assess adherence to existing medication
• Check inhaler technique.

If more intense treatment is appropriate, consider:

• Increasing dose of ICS to medium (adults) or low (children 5-12 years). If no improvement when LABA is added consider stopping LABA before increasing dose of ICS
• Consider adding an LTRA
• The addition of a long-acting muscarinic antagonist (LAMA) to ICS plus LABA may confer some additional benefit although results of clinical trials are currently inconclusive.
• Theophyllines may improve lung function and symptoms but are associated with an increase in adverse events.
• All patients whose asthma is not adequately controlled on recommended initial controller therapies should be referred for specialist care

Once asthma is controlled, decreasing treatment is recommended. Regular review as treatment is decreased is important.