Asthma in Adults - Recognition, Diagnosis and Management

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Effective Date: October 28, 2015

Recommendations and Topics


This guideline provides recommendations for the recognition, diagnosis and management of asthma in adults aged ≥ 19 years presenting in a primary care setting. For recommendations regarding asthma in patients aged 1 – 18 years see BCGuidelines.caAsthma in Children – Diagnosis and Management.

Key Recommendations

  • 30% of asthma patients are misdiagnosed; send all patients for spirometry, where available, to confirm the diagnosis of asthma.
  • Document the history of respiratory symptoms and objective evidence of airflow obstruction (i.e., spirometry) in all patients suspected of or with an asthma diagnosis, even in cases where the diagnosis seems certain.
  •  Do not prescribe asthma medications in cases of low clinical urgency and where patient has no documented objective evidence to support an asthma diagnosis.
  • As many as 90%1 of asthma patients use their inhalers incorrectly; regularly review a patient’s inhaler technique, especially when there is a poor or non-response to treatment.
  • To improve inhaler technique, especially in those with poor coordination, prescribe all patients a spacer when taking their metered dose inhalers (MDI).
  • To optimize self-management, consider sending all patients to an asthma education center, where available.
  • Complete a written asthma action plan with all patients and reassess this plan with the patient on a regular basis, especially after an exacerbation.


Asthma is a chronic inflammatory disease of the airways that is characterized by bronchial hyper-responsiveness and variable airflow obstruction. Asthma is a diverse disease that results in recurrent episodes, varying over time and in intensity, of one or more respiratory symptoms, such as wheezing, breathlessness, chest tightness or coughing.


The incidence of asthma in B.C. for patients between 5 and 54 years of age has remained constant since 2000/01, with an age standardized incidence rate for 2012/13 of 0.62%.2 This amounts to almost 16,000 new cases of asthma in B.C.2 The prevalence of asthma in B.C. has increased steadily since 2000/01 with an age standardized prevalence rate for 2012/13 of 10.53%, or an estimated 323,500 prevalent cases.2

The hospital, Medical Services Plan and PharmaCare costs per asthma patient in 2012/13 was $539, $617 and $271/patient respectively.2 In 2012/13, the total health care costs for patients with an asthma diagnosis in B.C. was over $460 million.2

Although deaths and hospital admissions due to asthma have decreased over the past ten years over 50% of patients have asthma that is not well controlled.3 Asthma that is uncontrolled not only leads to increased health care costs it also results in productivity and work losses.3, 4


Due to the high prevalence of asthma, assess all patients for asthma who present with common asthma respiratory symptoms (see Figure 1).


Take a history and perform a physical examination to determine if the pattern of respiratory symptoms supports the diagnosis of asthma (see Table 1. Adult clinical features to assess the probability of asthma).

A diagnosis of asthma is based on documenting a pattern of common asthma respiratory symptoms and objective evidence of variable airflow obstruction (see Investigations or Tests).

In patients with existing asthma diagnoses ensure there is documented evidence of variable airflow obstruction in their health care record.

Signs and Symptoms

Clinical features of asthma often are similar or overlap with other respiratory conditions, so ensure other possible diagnoses are ruled out before diagnosing a patient with asthma (see Differential Diagnosis).

In patients with existing asthma diagnoses and who respond poorly to treatment, assuming adherence, inhaler technique and co-morbidities are being treated, reconsider the diagnosis of asthma.

Table 1. Adult clinical features to assess the probability of asthma5, 6


NOTE: 30% of patients with a physician diagnosis of asthma are misdiagnosed .7-10 Thus, even in cases where the clinical diagnosis seems certain, it is still recommended that objective evidence of variable airflow obstruction be obtained.

Investigation or Tests

1. Spirometry

Spirometry (pre and post bronchodilator) is the preferred test for providing objective evidence of variable airflow obstruction.

NOTE: Negative spirometry results do not necessarily exclude the diagnosis of asthma.

If results are negative and clinical suspicion remains high, repeat spirometry on another occasion. Spirometry is more reliable when the patient is symptomatic.

The following result is typically considered objective evidence of variable airflow obstruction:

  • A 12 % or greater improvement in FEV1 and > 200 ml from baseline 15 minutes after use of an inhaled short-acting beta2 agonist (SABA).9

2. Peak flow monitoring

Peak flow monitoring (PFM) may be useful in providing objective evidence of variable airflow obstruction when:

  • Evidence is needed quickly and spirometry is unavailable (e.g., geography and access issues),
  • In suspected cases of work-related asthma where PFM can be used at the workplace, and
  • A patient is symptomatic and they have baseline peak flow readings for comparison (see Associated Document – Asthma Action Plan [PDF, 287KB]). 

Spirometry is the preferred test as PFM can be unreliable for the following reasons:

  • Reference values for peak flow readings are not as well standardized as spirometry,
  • Readings are not always well documented by the patient,
  • Readings are more variable than spirometry, and
  • Device may malfunction.

NOTE: Ensure the same meter is used for PFM as readings can vary substantially by device.

The following result is typically considered objective evidence of variable airflow obstruction:

  • A > 20% change after administration of a bronchodilator; a 20% change in values over time.11

3. Methacholine challenge

When spirometry and PFM results are negative and clinical suspicion remains, a methacholine challenge can be used to assess airway hyper-responsiveness. A positive result is diagnostic of asthma; however, false negatives may occur when the patient:

  • has seasonal asthma, and/or
  • is well controlled on pharmacological treatment, and/or
  • is currently asymptomatic.

4. Trial of pharmaceutical therapy

It is not recommended to use a trial of pharmaceutical therapy as evidence to support the asthma diagnosis.

In cases of low clinical urgency and timely access to spirometry consider delaying the initiation of pharmaceutical therapy until objective evidence of variable airflow obstruction can be obtained.

NOTE: once pharmaceutical therapy begins it is harder to obtain objective evidence to support the asthma diagnosis.

5. Chest x-ray

Chest x-rays are not routinely required but may be useful for excluding other diagnoses.  

6. Allergy testing

For patients whose symptoms are not well controlled, it may be helpful to identify allergens the patient is sensitive to. Inhalant allergen exposures have been shown to lead to asthma attacks in some patients. Food allergens are not a common producer of asthma symptoms.5 (See Appendix A: Lifestyle and Environmental Modifications [PDF, 98KB])

Differential Diagnosis

In cases of diagnostic uncertainty and/or there is no response to treatment consider the differential diagnosis. The following are the most common* alternative diagnoses to consider:

1. Chronic Obstructive Pulmonary Disease (COPD)

If clinical features of patient suggest COPD (e.g., patient is a current or past smoker), see Chronic Obstructive Pulmonary Disease (COPD) and/or refer to specialist.

2. Asthma-COPD Overlap Syndrome (ACOS)

In patients that are older and who are smokers it may be hard to distinguish if the patient has asthma or COPD, and in some cases the patient may have ACOS. ACOS is characterized by airflow limitation and is identified by the symptoms it shares with both asthma and COPD. For more information see Global Initiative for Asthma’s Global Strategy for Asthma Management and Prevention Chapter 5: Diagnosis of asthma, COPD, and asthma-COPD overlap syndrome (ACOS), website:

3. Work-related Asthma

Work-related asthma includes both occupational asthma (asthma symptoms that are a result of exposure to workplace irritant/allergen) and work-aggravated asthma (pre-existing asthma symptoms that worsen due to exposure of workplace irritant/allergen).12 Work-related asthma accounts for approximately 5-20%13 of new adult onset asthma cases and at least 15%14 of all adult asthma cases; thus, resulting in a significant socioeconomic loss to society. Ask all patients about potential occupational exposures at the workplace.5 For more information see Appendix A (PDF, 98KB) Table 1. Examples of occupational exposures that can contribute to asthma.

Refer all patients with suspected work-related asthma to a specialist.




  • Asthma is predominantly treated using pharmaceutical therapy recommended through a stepwise approach (see Pharmacological Management - Stepwise Approach). The stepwise approach bases a patient’s treatment on their current corresponding level of asthma control (see Assessment of Asthma Control below).
  • Identify asthma triggers and recommend relevant lifestyle and environmental modifications to support the treatment plan (see Appendix A [PDF, 98KB]).
  • Complete a personalized written asthma action plan with the patient so they know how to self-manage worsening asthma symptoms and when to seek medical help (see Self-Management and Asthma Action Plan [PDF, 287KB]).

Assessment of Asthma Control

Assess asthma control at the time of diagnosis, when creating/modifying a treatment plan and when monitoring treatment outcomes. Consider both symptom control and risk of a future asthma attack. 

1. Asthma Symptom Control15, 16


0 points = well controlled asthma symptoms

1-2 points = partly controlled asthma symptoms

≥ 3 points = uncontrolled asthma symptoms

2. Risk of a Future Asthma Attack8, 15, 17-19

Does the patient have any of the following risk factors:

  • ≥ 1 severe attack (e.g., requires hospitalization, oral steroid use) in last 12 months
  • Uncontrolled asthma symptoms
  • Co-morbidities: obesity, rhinosinusitis, confirmed food allergy
  • Ever intubated or in intensive care unit for asthma
  • Excessive SABA use (> 1 x 200-dose canister/month)
  • Exposure to tobacco smoke
  • Inadequate inhaled corticosteroid (ICS): not prescribed ICS; poor adherence; incorrect inhaler technique
  • Low FEV1, especially if <60% predicted
  • Major psychological or socioeconomic problems (e.g., depression in older adults)
  • Sputum or blood eosinophilia
  • Pregnancy

If the patient has any of these risk factors they are at risk for future asthma attacks. Consider strategies to eliminate modifiable risk factors (e.g., tobacco cessation programs, weight loss programs, etc.).

Pharmacological Management – Stepwise Approach

Refer to Table 2. Initiating inhalers – stepwise approach to treatment

Initial Treatment:

  • Choose step based on assessment of asthma control (symptom control & risk of future asthma attacks) and patient’s preference (e.g., cost, willingness to use the prescribed device, and ability to adhere to treatment plan).
  • Aim to have the patient at the lowest step needed for asthma control.

Step up:

  • Consider if symptoms not routinely controlled or if patient continues to have recurrent asthma attacks at current step.
  • Before stepping up, confirm the diagnosis, review patient’s self-management education and lifestyle/environmental modifications and ensure medication adherence and correct inhaler technique.

Step down:

  • Consider stepping down if symptoms are controlled for ≥ 3 months and risk of asthma attack is low.

Table 2. Initiating inhalers – stepwise approach to treatment



Successful self-management education for patients includes the following:

1. Discussing with the patient:

  • the condition (e.g., asthma is a chronic condition, how asthma attacks occur),
  • the goals of treatment (e.g., what well controlled asthma look like, patient’s concept of quality of life), and
  • the treatment options (e.g., patient’s willingness to modify lifestyle/environment based on trigger identification and to use pharmacological therapy). There is minimal evidence supporting the greater efficacy of dry powder inhalers over metered dose inhalers & spacers in adult patients.20 Choose inhaler based on the patient’s preference (e.g., cost, willingness to use the prescribed device, and ability to adhere to treatment plan). See Appendix A (PDF, 98KB) and Appendix C: Asthma Medication Table (PDF, 128KB) for more information.

2. Developing a written asthma action plan with the patient (see Asthma Action Plan [PDF, 287KB]).

3. Referring patient to an asthma education program, where available. See Physician and Patient Resources.

4. Reviewing the following with the patient at regular office visits (see Associated Document – Asthma Patient Care Flow Sheet for Adults [PDF, 57KB]):

  • medication adherence (e.g., is patient taking their medication as prescribed?) see Figure 2,
  • inhaler technique (e.g., have patient demonstrate how they take their inhalers),
  • level of symptom control and ability to follow lifestyle modifications,
  • how to monitor symptoms and in patients with poor perception of their symptoms how to monitor peak flow,21 and
  • Asthma action plan (modify if necessary).



Treating acute loss of asthma control5

1. Assess the severity of the asthma attack:

  • Severe – life-threatening: While arranging urgent transfer to an acute care facility treat the patient with short-acting beta2-agonists (SABA), controlled oxygen and oral corticosteroids (OCS).
  • Mild-moderate: treat in the primary care setting (see Goals of treatment and Treatment steps below).

2. Goals of treatment:

  • Rapidly relieve airflow obstruction,
  • Identify and address the cause of the asthma attack, and
  • Reduce risk of relapse by reviewing and adjusting maintenance treatment plan.

3. Treatment steps:

  • Administer SABA with a spacer 2-6 puffs every 20 min for first hour then decrease frequency based on patient response. 
  • A good response to SABA is PEF > 80% of personal best, 50-79% is an incomplete response (administer OCS), and <50% PEF is a need for urgent medical care. See Asthma Action Plan (PDF, 287KB).
  • Monitor patient closely and continue treatment until peak flow readings improve > 60-80% of patient’s best.
  • Give OCS to patients who are not responding to SABA, deteriorating or who have increased their inhaler doses before presenting. (OCS adult dose 1mg/kg/day, max 50mg/day for 5-7 days). 
  • If patient improves: review Asthma Action Plan (PDF, 287KB) (make modifications as necessary), review how to monitor symptoms, review inhaler technique and adherence, what to do if symptoms worsen and schedule follow-up appointment (1 week later) if patient stabilizes.
  • Increase controller medications for the next 2-4 weeks and prescribe controllers for patients who are not taking them already.
  • If patient gets worse and is admitted to hospital: depending on the clinical context, schedule follow-up appointment for 2-7 days after the asthma attack. See Self-Management.
  • If there is no response to treatment or patient continues to deteriorate arrange urgent transfer to acute care facility.


Management of poor or incomplete response to long-term treatment

If there is a poor or non-response to proposed treatment plan, consider the following:

1. Poor adherence with medications due to:

  • cost of prescribed medications is a significant barrier. Ensure patient can afford the medication prescribed. Discuss patient’s drug plan to ensure appropriate coverage. See Appendix C – Asthma Medication Table (PDF, 128KB)
  • inhaler burden – try to prescribe less inhalers if possible (e.g., combination devices versus several individual inhalers that do the same thing)

2. Incorrect inhaler technique - prescribe spacer and review its use.20

3. Review and readdress risk factors and co-morbidities (e.g., smoking, triggers, rhinosinusitis, obesity and gastro-esophageal reflux disease). 

4. Confirm and review diagnosis and refer to specialist for further investigation.



1 National Asthma Council Australia. Inhaler technique in adults with asthma or COPD: information paper for health professionals. 2008. Available from: Accessed November 14, 2014.

2 British Columbia Ministry of Health. Primary Health Care (PHC) Registry. November 2013.

3 Yawn BP. The role of the primary care physician in helping adolescent and adult patients improve asthma control. Mayo Clin Proc. 2011; 86(9):894-902.

4 British Thoracic Society (BTS) & Scottish Intercollegiate Guidelines Network (SIGN). British guideline on the management of asthma: A national clinical guideline. 2014 (revised). Accessed online December 3, 2014 at: (192 pages).

5 Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2014:1-132. Available from: Accessed November 14, 2014.

6 Lucas AEM, Smeenk FWJM, Smeele IJ et al. Overtreatment with inhaled corticosteroids and diagnostic problems in primary care patients, an exploratory study. Family Practice 2008; 25:86-91.

7 Shaw D, Green R, Berry M et al. A cross-sectional study of patterns of airway dysfunction, symptoms and morbidity in primary care asthma. Prim Care Respir J 2012; 21(3):283-7.

8 Blakey JD, Zaidi S, Shaw DE. Defining and managing risk in asthma. Clinical & Experimental Allergy 2014; 44:1023-32.

9 Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26:948-968.

10 Aaron SD, Vandemheen KL, Boulet LP, et al. Overdiagnosis of asthma in obese and nonobese adults. CMAJ 2008; 179(11):1121-31.

11 U.S. Department of Health and Human Services, National Institutes of Health, National Heart, Lung and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Full Report 2007. Page 191.

12 Mazurek JM & White GE. Work-related asthma. Morbidity and Mortality Weekly Report. 2015;64(13):343-346. Accessed online April 24, 2015.

13 Baur X, Sigsgaard T, Aasen TB, et al. ERS Task Force Report. Guidelines for the management of work-related asthma. Eur Respir J 2012; 39(3):529-545.

14 Baur X & Sigsgaard T. Editorial The new guidelines for management of work-related asthma. Eur Respir J 2012; 39(3):518-519.

15 Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2014:1-132. Available from: Accessed November 14, 2014. Page 17.

16 U.S. Department of Health and Human Services, National Institutes of Health, National Heart, Lung and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Full Report 2007. Page 77.

17 Park H-W, Kim T-W, Song W-J, et al. Prediction of asthma exacerbations in elderly adults: results of a 1-year prospective study. (letter to the editor). JAGS 2013; 61(9):1631-2.

18 Al-ani S, Spigt M, Hofset P et al. Predictiors of exacerbations of asthma and COPD during one year in primary care. Family Practice 2013; 30:621-8.

19 Blakey JD, Woolnough K, Fellows J, et al. Assessing the risk of attack in the management of asthma: a review and proposal for revision of the current control-centred paradigm. Prim Care Respir J 2013; 22(3):344-52.

20 Barry PW, O'Callaghan C. The influence of inhaler selection on efficacy of asthma therapies. Adv Drug Deliv Rev. 2003;55:879- 923.

21 Turner MO, Taylor D, Bennett R, et al. A randomized trial comparing peak expiratory flow and symptom self-management plans for patients with asthma attending a primary care clinic. Am J Respir Crit Care Med 1998; 157(2):540-6.

Physician and Patient Resources

Allergy and Asthma Information Association: Mission is to create safer environments and improve quality of life for Canadians affected by allergy, asthma, and anaphylaxis by empowering individuals and providing education, leadership, national voice.

Asthma Education Centre Resources: Provides contact information for provincial certified asthma education centres, listed by Health Authority.

The Asthma Society of Canada: Provides a variety of free educational materials and resources with the latest asthma news and information.

BC Lung Association: A non-profit and volunteer-based health charity, the BC Lung Association offers in-depth information on asthma programs and educational resources.

  • Website:
  • Phone: Greater Vancouver 604-731-5864 or Toll free in B.C. 1-800-665-5864

The Canadian Lung Association: Publishes the Lung Association Asthma Handbook; a comprehensive guide that is written in a clear, easy-to-understand style for people with asthma.

HealthLink BC: provides easy access to non-emergency health information and services. Translation services are available in over 130 languages on request.

  • Website:
  • Phone: In B.C. 8-1-1.
  • Phone: TTY (deaf and hearing-impaired) 7-1-1

Instructions on inhaler technique: Provides detailed instructions on how to use various types of asthma inhalers.

QuitNow: An internet-based quit smoking service, available FREE-of-charge to all British Columbia residents. Translation services are available in over 130 languages on request.

RACE - Rapid Access to Consultative Expertise program: A telephone advice line from a selection of specialty services for family physicians and nurse practitioners.

  • For Vancouver Coastal Health Region/Providence Health Care/Interior Health/Fraser Health - or by telephone  604-696-2131 (Vancouver area) or 1-877-696-2131 (toll free); Monday to Friday, 8 am to 5 pm
  • For Northern Health - or by telephone 1-877-605-7223

Diagnostic code: 493 (Asthma)


Associated Documents

The following documents accompany this guideline:


This guideline is based on scientific evidence current as of the Effective Date.

This guideline was developed by the Guidelines and Protocols Advisory Committee, approved by the British Columbia Medical Association, and adopted by the Medical Services Commission.


The principles of the Guidelines and Protocols Advisory Committee are to:

  • encourage appropriate responses to common medical situations
  • recommend actions that are sufficient and efficient, neither excessive nor deficient
  • permit exceptions when justified by clinical circumstances.

Contact Information

Guidelines and Protocols Advisory Committee
Victoria BC V8W 9P1


Web site:



The Clinical Practice Guidelines (the “Guidelines”) have been developed by the Guidelines and Protocols Advisory Committee on behalf of the Medical Services Commission. The Guidelines are intended to give an understanding of a clinical problem, and outline one or more preferred approaches to the investigation and management of the problem. The Guidelines are not intended as a substitute for the advice or professional judgment of a health care professional, nor are they intended to be the only approach to the management of clinical problem. We cannot respond to patients or patient advocates requesting advice on issues related to medical conditions. If you need medical advice, please contact a health care professional.