|Year : 2023 | Volume
| Issue : 2 | Page : 87-92
Clinical utility of peak flow meter in asthma diagnosis and monitoring in low- and middle-income countries: A narrative review
Oluwafemi T Ojo, Adeola O Ajibare, Ayoola Odeyemi, Temitope Fapohunda, Olufunke O Adeyeye
Department of Medicine, Lagos State University Teaching Hospital, Ikeja, Lagos, Nigeria
|Date of Submission||02-Jan-2023|
|Date of Decision||29-Jan-2023|
|Date of Acceptance||03-Mar-2023|
|Date of Web Publication||21-Mar-2023|
Oluwafemi T Ojo
Department of Medicine, Lagos State University Teaching Hospital, 1-5 Oba Akinjobi Way, Ikeja, Lagos
Source of Support: None, Conflict of Interest: None
Low- and middle-income countries (LMICs) suffer a disproportionate burden of asthma-related deaths. This may be attributed to the underdiagnosis and undertreatment. It remains unclear the extent to which the access to utility of peak flow meters (PFMs) affect the mortality rates recorded across LMICs. The purpose of this narrative review was to offer a comprehensive overview of PFMs’ clinical value for diagnosing and monitoring asthma in low- and middle-income nations. Using the standards for conducting a narrative review, this paper carried out a literature search on three major databases: Google Scholar, ResearchGate, and PubMed. Search terms were created from the variables present in the topic and strung together to find relevant literature. Exclusion criteria were used to ensure that the chosen articles were relevant after a trickle of articles was collected from various databases on the internet. There is limited knowledge about the clinical utility of PFM in LMICs despite the evidence that it can be used to demonstrate large airway obstruction. There is also limited access to the device in most health facilities and patients for self-monitoring. There is a need for more awareness on the usefulness of peak flow among doctors on the utility of the device for asthma diagnosis and monitoring. There is also a need for more research to assess the impact of the poor use of the device on asthma diagnosis, management, and overall outcome.
Keywords: Airway obstruction, asthma, lung function test, peak flow meter, spirometry
|How to cite this article:|
Ojo OT, Ajibare AO, Odeyemi A, Fapohunda T, Adeyeye OO. Clinical utility of peak flow meter in asthma diagnosis and monitoring in low- and middle-income countries: A narrative review. Int J Med Health Dev 2023;28:87-92
|How to cite this URL:|
Ojo OT, Ajibare AO, Odeyemi A, Fapohunda T, Adeyeye OO. Clinical utility of peak flow meter in asthma diagnosis and monitoring in low- and middle-income countries: A narrative review. Int J Med Health Dev [serial online] 2023 [cited 2023 May 28];28:87-92. Available from: https://www.ijmhdev.com/text.asp?2023/28/2/87/372147
| Introduction|| |
Scope of the narrative review
Asthma is a chronic, noncommunicable disease affecting both children and adults across the globe. The disease affects over 300 million people worldwide and has a global prevalence of self-reported, doctor-diagnosed cases of about 4.3%., Its prevalence varies widely across countries in the world with higher prevalence recorded among high-income countries and lower prevalence among low- and middle-income countries (LMICs). Among children, the burden of the disease cuts across LMICs with variabilities in geographical dimensions, income distribution, urbanization, lifestyles, infrastructure, and health systems. In addition, this burden among LMICs varies strongly; a 2.8% prevalence among children in Indonesia to a 37.6% prevalence among children of the same age in Costa Rica, and a 3.4% prevalence among children in Albania to a 31.2% among children of the same age living in the Isle of Man.
There is a notable switch in the risk for asthma at puberty. Research shows that girls are more at risk of being asthmatic than boys; there is about a 20% higher prevalence of the disease in women than in men. One study linked this to characteristic smaller airways to lung size found among preadolescent boys when compared with those of girls in the same age group. This, however, reverses with the onset of adolescence. In addition to this, there is a potential hormonal and genetic component associated with the increased risk for asthma disease. Obesity and smoking were also identified to increase the risk for the disease.
Preventive approaches to solving asthma are yet to be established; however, it is recommended that pregnant women and infants avoid tobacco smoke. In addition, sufficient vitamin D levels in pregnancy and avoidance of broad-spectrum antibiotics should be ensured in the first year of life.
Asthma is characterized by symptoms, including cough, wheeze, and chest pain, serving as a source of disability, significantly reducing the quality of life of the people who suffer from it and may lead to avoidable deaths in both children and adults. The symptoms often associated with asthma are, however, nonspecific and sometimes associated with several other illnesses and diseases; a careful history record is thus recommended to ensure that the symptoms presented are not because of an alternative diagnosis.
The disease is diagnosed and monitored using a variety of tools, one of which is the peak flow meter (PFM). It helps to objectively assess and monitor patients’ airway function to determine how quickly the patient can blow air out of their lungs using forceful exhalation after maximum inhalation. There are two major types of PFMs: the low-range PFM for younger children and the standard-range PFM for older children and adults. Children younger than 10 years old have characteristically smaller lungs than older children and adults; thus, each individual must be prescribed the age-appropriate PFM.
In addition to the clinical diagnosis of asthma, the PFM is also used to identify variations in airflow obstruction, bronchodilator response, and patterns in occupational asthma. The device can also be used to monitor the progression of the disease and set up a management plan. The PFM has several advantages that make it the best device for diagnosing and monitoring asthmatic disease; it is small, easy to use, and affordable, allowing the patients to use it at home to monitor day-to-day breathing variations. Furthermore, it is accurate at identifying the progress of the disease and can help to predict asthmatic attacks. A major limitation of the device, however, is its inability to assess airflow in smaller airways; thus, it may sometimes underestimate the degree of airflow limitation.
Regardless of this limitation, the PFM remains one of the easiest and fastest methods of diagnosing and monitoring asthma and predicting future attacks. Yet, a report from the World Health Organization reveals that many countries lack access to the device. This inequality in the access to the PFM significantly affects LMICs when compared with high-income countries. In addition, this inequality may account for the higher asthma-related mortality rates across LMICs, despite the higher prevalence recorded in high-income countries. Nonetheless, there is a need to examine the availability and utility of the device across LMICs and explore the past and recent trends on the topic matter.
Purpose of the narrative review
Although high-income countries have a higher recorded prevalence of asthma, LMICs suffer a disproportionate burden of asthma-related deaths. Whereas this may be attributed to the underdiagnosis and undertreatment, it remains unclear that the extent to which the access to and clinical utility of PFMs affect the mortality rates recorded across LMICs.
The purpose of this review is to thus provide a holistic overview of the clinical utility of PFMs in LMICs.
| Materials and Methods|| |
Using the standards for conducting a narrative review, this paper carried out a literature search on three major databases: Google Scholar, ResearchGate, and PubMed. Because of the limited amount of literature turnout, there were no restrictions on the years of publication.
Search terms were created from the variables present in the topic and strung together to find relevant literature. The search terms combined “peak flow metre/meter” and the subheadings “LMICs,” “clinical use,” “diagnosis,” “monitoring,” and “management.”
- Observational studies: Cohort studies, case controls, and cross-sectional studies.
- Studies that reported the primary outcome: Use of PFM.
- Study retrievable in the English language.
- Editorials, interventional studies, commentaries, and letters to editors.
- Duplicates/replicates of studies.
- Studies not retrievable in the English Language.
- Studies with no full-text access.
- Studies which focused on areas beyond the scope of the review.
Data extraction and management
Identified studies were screened independently in pairs and blindly.
- i. Level 1 involved screening of identified studies for the study design. Only observational studies were accepted.
- ii. Level 2 involved screening of identified studies in the titles and abstracts using entry terms and keywords.
- iii. Level 3 involved further screening of the contents of articles by reading the full article using the same search strategy.
- iv. Level 5: Studies were screened at outcome levels to select those that reported the primary outcome.
Screened studies were selected based on study characteristics: study design and inclusion/exclusion criteria.
The burden of asthma in LMICs
Asthma has always been viewed as a condition that predominantly affects high-income countries; whereas communicable diseases have traditionally been prioritized in low- and middle-income nations. In certain LMICs, however, chronic noncommunicable diseases are increasingly understood to have a higher impact than communicable diseases. Despite being aware of this shift in epidemiology, LMICs have limited reliable epidemiological data on asthma.
The significance of assessing health outcomes in LMICs is shown by a study conducted in Uganda by Kirenga et al. A cohort of 449 people living with asthma was recruited for the trial and was tracked for 2 years to record rates of exacerbations and mortality. During the relatively brief research period, 3.7% of patients died overall, and nearly two thirds of those fatalities were thought to be attributable to asthma. In addition to, 32% of participants had more than three exacerbations each year compared with 60% of patients who had one or more per year. These findings point to a significant care gap for the condition. The study’s findings also suggest that to enhance outcomes in this situation, a priority response is required.
Another study assessing the prevalence of asthma in South Asia revealed that the prevalence of asthma among adults varied from country to country within the region. The study revealed that India had the highest prevalence of the disease with an average prevalence of 6.3%; Sri Lanka had the second highest prevalence of 5.3%; whereas, Pakistan had the lowest prevalence in the region with a prevalence of 3.7%. Another study, however, reported the prevalence of asthma in India ranging from 2% to 14% depending on previous medical history.
In Africa, the prevalence of asthma varies from one country to the other. South Africa had the highest reported prevalence of the disease with a prevalence of 53%, second was Egypt with a prevalence of 26.5%, 18.4% in Nigeria, and 16.3% in Ethiopia. The country with the lowest reported prevalence in the region, according to the study, was the Gambia with a prevalence of 3.9%.
A comprehensive systematic study comprising of LMICs revealed that, on average, the prevalence of asthma varied greatly within rural and urban regions. It was revealed in the study that urban regions tended to have a higher prevalence of the disease than rural regions within the same countries. This coupled with the results revealing that high-income countries tended to have a higher prevalence of asthma than LMICs show that the apparent prevalence of asthma may be, to some extent, affected by urbanization.
Treatment and management of asthma in LMICs
The treatment and management of asthma are fundamentally similar in high-income countries and LMICs. However, due to the various barriers such as the prioritization of acute care over chronic care and lack of affordability and availability of medicine, there is a slight variation in the approach taken by health professionals in LMICs to treating and managing asthma.
The central management of asthma in high-income countries is done with the use of regularly inhaled corticosteroids (ICS) and the bronchodilator inhaler. ICS and the bronchodilator inhaler are regularly utilized to improve the control of symptoms and limit the risks of aggravations and asthma-related mortalities. Results have shown that they can reduce the risk of asthma-related mortality and hospitalization by over 50% and 31%, respectively.
However, in LMICs, the recommendations for managing and treating asthma are less sophisticated and frequently based on the antiquated notion that people with asthma who experience symptoms less frequently than three times per week do not require ICS. When ICS is prescribed, some LMIC residents typically cannot access it, while others find it to be costly.
Therefore, the most typical therapy strategy used in LMICs starts with the prescription of salbutamol, which is then followed by an increase in dosage if symptoms continue., In severe situations of symptoms persistence, oral theophylline called Franol (Theophylline and Ephedrine Hydrochloride per tablet) or Prednisone are also recommended.
Studies on the usage of these drugs to treat asthma in LMICs are scarce. However, one study examined how Franol affected asthmatic symptoms. According to the study, the drug significantly increased bronchodilation for nearly an hour. Prednisolone and salbutamol were both beneficial in relieving asthmatic symptoms in children for up to 30 min, according to the results of another double-blind trial.
The Global Initiative for Asthma has, however, recommended that oral theophylline should no longer be used in the treatment of asthma, as it was found to be linked to several adverse effects while offering weak evidence of benefits. The initiative has also advised against prescribing salbutamol regularly for adults and adolescents except in cases where the patient is likely to be adherent to the prescribed doses.
The disease is often regarded as critical rather than chronic by many patients in LMICs. Oftentimes, health professionals reinforce this perception by providing emergency services for treating exacerbations but very few follow-up services. Thus, the management of asthma, beyond the scope of treating and resolving exacerbations, is often limited in LMICs. It is recommended by the Global Initiative for Asthma that the progression of asthma disease and predictions for exacerbations be monitored using PFM.
Asthma diagnosis and monitoring in LMICs
Clinical indications of varying obstructions in expiratory airflow and a record of recognizable symptoms are used to make the clinical diagnosis of asthma. This evidence is often obtained by spirometry testing or bronchial provocation challenge testing in health-care facilities with adequate resources. These techniques are still remarkably underutilized in LMICs, even when the necessary tools are available perhaps because they are expensive or time-consuming, as it frequently takes many tests to ascertain the variability in airflow., Health professionals in many LMICs, thus, depend more on clinical manifestations and frequently use symptomatic approaches for diagnosis and treatment because these diagnostic technologies are typically unavailable there, and the differential diagnosis of asthma may also include endemic respiratory diseases like HIV/AIDS or tuberculosis.
On the premise that the ailment is underdiagnosed and undertreated, which is true for the majority of LMICs, the idea of symptomatic diagnosis emphasizes pattern identification at the expense of precision. But in high-income nations, symptomatic diagnosis can result in overdiagnosis and overtreatment of asthma, as well as inadequate or incorrect treatment of asthma., To improve the management of respiratory diseases in LMICs, particularly in nations with a high prevalence of tuberculosis, several techniques, including structured approaches to primary care diagnostic assessment of patients presenting with respiratory symptoms, have been established.,
In cases when spirometry is not available, the WHO recommends using the PFM to confirm the presence of variable expiratory airflow limitation. The organization recommends using it to support a clinical diagnosis based on history and views it as a crucial tool in the diagnosis of various chronic respiratory disorders. There is a claim that the prevalence of asthma diagnoses increases by more than 20% in areas where PFMs are employed.
The clinical use of PFMs in LMICs
The commonly available tests for asthma are the peak expiratory flow rate (PEFR) and spirometry. A PFM is a portable instrument that gauges how quickly someone may forcefully exhale after reaching their maximum inhalation. The PFM aids in measuring the airflow through the airways and, thus, aids in identifying the severity of obstruction present. PEFR are performed to demonstrate reversible airflow obstruction, the hallmark physiological derangement in asthma. The PEFR meter measures the maximum flow rate generated during a forceful exhalation starting from full lung inflation (peak flow). Airflow obstruction on a PEFR meter is present when the patient’s PEFR is less than his/her predicted flow according to age, sex, and height or his/her personal best for those with previous measurements. A short acting bronchodilator is administered, and the PEFR is repeated after 15 min. An increase of 60 mL or 20% in the PEFR represents reversible airflow obstruction. It must be noted, however, that PEFR is currently not recommended for asthma diagnosis by most international guidelines. However, PEFR provides additional objective evidence of airflow obstruction in the absence of spirometry. EFR self-monitoring proved to be a more useful asthma tool than symptom self-monitoring.
Onadeko et al. demonstrated the usefulness of peak flow in the 70 s in assessing the effect of bronchodilator on the airway in a multicenter clinical trial of inhaled B-agonist, salmeterol, that was carried out to assess its efficacy in adult Nigerian asthmatic patients. They found peak flow helpful in assessing lung function which showed significant improvement. Ndarukwa et al. in a two-stage Delphi model in Zimbabwe collected data in order to develop an algorithm of asthma diagnosis and management in Zimbabwe and noted the importance of peak flow in assessing airway obstruction. He, however, noted that there are challenges attributed to lack of basic equipment such as spirometers and peak expiratory flow meters and tests which included IgE tests, Skin Allergen Tests, and Radioallergosorbent test for optimal asthma diagnosis. Despite the usefulness of peak flow in building up evidence in the diagnosis of asthma and self-monitoring, the device is still highly underutilized. Hounkpati et al. in a descriptive survey through auto-questionnaire conducted among physicians and interns to evaluate their attitude in the management of asthma in Togo reported that PFM was not known by majority of the investigated physicians and was prescribed by only 14.5% of them. This implies that large number of doctors may be unaware of the clinical utility of this cheap device, and this calls for attentions of pulmonologists to raise awareness on the utility of PFM for asthma diagnosis and monitoring. Chima et al., on the contrary, in a descriptive cross-sectional study in Nigeria, assessed the knowledge of asthma prevalence, asthma risk factors, and management practices among physicians reported that 95 (81.2%) had seen a PFM, but only 41 (35.5%) use it in asthma diagnosis. This implies poor utility of the device for asthma diagnosis despite being aware of the device. Chokhani et al. carried out a survey aimed to understand the physicians’ practice pattern and challenges faced while treating their patients with asthma in five countries—Malaysia, Nepal, Myanmar, Morocco, and Lebanon and reported that approximately, 38% physicians always used spirometry for diagnosis and only 12% physicians always recommended PFM for home-monitoring. There are opportunities to improve the use of diagnostic and monitoring tools for asthma. Adeyeye et al. examined the utilization of asthma guidelines in the management of asthmatics as well as the use of inhaler devices among the asthmatics presenting for specialist assessment and treatment in Lagos, Nigeria, and reported that majority of the asthmatics did not receive any health education about their condition and possession of PFM and use were low among the patients with only 22 (20.8%) having one. This implies that asthma control is poor among the patients in Lagos, Nigeria. Ehrlich et al. in a cross-sectional study based on random community sample of schools assessed the extent of recognition and appropriate management of childhood asthma in a large suburban area of Cape Town and reported that only a minority of parents reported the child ever having used a PFM.
The implication of these findings is such that there exists inequality in the availability of PFMs across countries in the world. This inequality affects LMICs more than in high-income countries. There is also knowledge gap about the clinical utility of this cheap device to diagnose and monitor patients with asthma in LMICs especially in Africa. This calls for a need for more awareness among doctors on the usefulness of this device, and there is also a need for stake holders to make it more assessable to clinicians and patients.
Few studies have evaluated the clinical application of PFMs in LMICs. Therefore, more research is required to determine the clinical utility of PFMs in the diagnosis and monitoring of asthma in low- and middle-income nations.
The number of publications available for this narrative review was constrained because this study was self-funded, and the researcher was only afforded access to free-text articles.
| Conclusion|| |
There is limited knowledge about the clinical utility of PFM in low-medium income countries despite the evidence that it can be used to demonstrate large airway obstruction. There is also limited access to the device in most health facilities and patients for self-monitoring. There is a need for more awareness on the usefulness of peak flow among doctors on the utility of the device for asthma diagnosis and monitoring. There is also a need for more research to assess the impact of the poor use of the device on asthma diagnosis, management, and overall outcome.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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