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World Asthma Day 2020 Special Interview: Part 1
As Nigeria joined the rest of the world to mark the 2020 World Asthma Day on Tuesday May 5, renowned Professor of Medicine and Consultant Chest Physician at the Obafemi Awolowo University/ Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, Professor Gregory Erhabor takes a look at asthma management in Nigeria and concludes that while the country seems to have made some progress over the years, the condition still remains poorly diagnosed and “inadequately managed,” due to low education, dearth of asthma medications and devices for managing the condition. Prof. Erhabor who is also the President/Founder of Asthma and Chest Care Foundation, member, Council of Global Governors of the American College of Chest Physicians and the Editor-in-Chief of the West African Journal of Medicine, also explains the role of obesity as an emerging cause of asthma in this first part of the special interview. EXCERPTS
As the world marks the 2020 World Asthma Day, can we say Nigeria is doing well in the area of Asthma management?
We have come a long way from where we used to be. The World Asthma Day (WAD) is an annual International event with goals to improve asthma awareness and care around the world. Several chest physicians across the nation now celebrate WAD yearly to increase awareness in all the geopolitical zones by educating healthcare professionals, patients, caregivers and the general public. This has improved public alertness thereby prompting quick response to patients with asthma when they need help.
Also, more resident doctors are showing interest in pulmonology and training to become chest physicians. This has resulted in more standardized ways of management in our various tertiary and secondary hospitals. Basic asthma medications, inhalational therapy and nebulizers are increasingly being used by a lot of hospitals and this shows some measure of progress. Although, this still runs short of what is expected and there is still a big divide between what happens in tertiary hospitals and primary and secondary care services.
For advancement of any disease, it is a triangle of patient management, training and research. There is still poor government involvement and active support to strengthen research and patient care in asthma in Nigeria. Moreover, asthma is poorly diagnosed and still inadequately treated even in tertiary hospitals because of poor education and lack of availability and affordability of asthma medications.
What is the prevalence rate of asthma in Africa as a whole and Nigeria in particular?
Asthma prevalence ranges from high prevalence countries like South Africa, which has a prevalence of 33.1%, to low prevalence countries like Gambia with prevalence of 4.4% while Nigeria prevalence falls in-between. Works that have been done in the ISAAC study and studies done by scholars in Nigeria shows that the prevalence ranges from 5% to 18.7% depending on the cohort being studied. Most studies show that there is an urban-rural gradient with more asthma being diagnosed in urban than rural areas. Anecdotal evidence had shown that about 15 million Nigerians may have asthma. Works have been done in different regions of Nigeria with varying prevalence rates and meta-analysis is being conceived to see if we can correlate all the studies together to come up with something that will be more representative of the asthma picture in Nigeria.
Apart from smoking and other activities that trigger asthma attacks, are there new risk factors Nigerians need to watch?
Basically, asthma results from interplay of genetic and environmental factors, a situation known as nature and nurture. Individuals with family history of asthma are prone to developing asthma. When individuals with genetic predisposition to asthma get exposed to certain triggers in the environment, they develop symptoms of asthma. Triggers are extremely small and lightweight particles transported through the air and inhaled into the lungs. They precipitate asthma attacks and are usually found in the environment. Triggers include pollens, house dust mite, cockroach allergens, cold air, spores, fumes, smoke, sprays, perfumes; exercise, certain drugs like aspirin, tobacco smoke, prolonged exposure to air pollution, and agents found at work place like chemicals, amongst others. People with allergies such as allergic rhinitis, conjunctivitis, sinusitis, or atopic eczema are predisposed to developing asthma. The most common trigger still remains house dust mite. However, there is new interest in the role of obesity in the development of asthma.
Can you please explain how obesity cause asthma?
Within the last few years, there has been a growing number of literatures on the obese asthma syndrome. The detailed discussion of this topic will be beyond the scope of this article. How obesity contributes to asthma in an individual may vary. However, these are a few ongoing factors that have come up as the relationship:
- Obese people are more susceptible to many strong risk factors of asthma like allergens, chemicals, cigarette smoking and air pollution. There are many things that have been attributed to it but one common one is that the diet that promotes obesity such as the western diet has high levels of saturated fatty acids, low fibers, low antioxidants and high in sugar. There is a growing literature that the harmful effects of these dietary components could lead to increased neutrophilic inflammation which predispose to asthma and increased bronchodilator response.
- Also, there has been some studies showing that obesity can lead to low circulating Vitamin D and vitamin D deficiency has been implicated in the development of asthma and obesity.
- There is also what we call a bidirectional relationship. Obesity predisposes to asthma and asthma also predisposes to obesity. For example, sixty percent of adults with severe asthma in United States are obese. Obese patients have worse asthma control and lower quality of life. Obese asthmatics do not respond as well to standard controller medications like inhaled corticosteroids and combination long-acting beta 2 agonists with inhaled corticosteroids (LABA/ICS), as non-obese patients. Furthermore, obese adults have 1.6 to 3 times more risk of developing wheeze and asthma.
- Obesity can cause or worsen gastroesophageal reflux disease (GERD) and sleep apnea and both of these conditions have caused increased risk of developing asthma.
- Patients with asthma who are obese usually have chronic low-grade systemic inflammation which is due to the release of certain pro-inflammatory chemicals (cytokines) in the body. One of these is Leptin which is synthesized by adipose tissue (fat tissue) and its levels in the body increases with obesity. Leptin and leptin receptors are found within the cells of the lungs, promote inflammation and contribute to bronchial asthma. High levels of leptin cause impairment of lung function, increased airway hyperresponsiveness (AHR) including exercise-induced bronchoconstriction and worsening of asthma symptoms.
Why is Asthma more prevalent in children than adults? Are there some genetic factors associated with it too?
Asthma is really not more prevalent in children as newer studies have shown. However, we need to do more multinational and intercontinental research to evaluate the prevalence because it appears asthma is still much underdiagnosed in both children and adults. Asthma runs a bimodal pattern – childhood asthma and adult asthma. Asthma tends to be more in number and in severity among boys than girls in childhood. This becomes balanced at puberty between the ages 12-14. However, between 15 to 50 years of age, females predominate. Early childhood events may influence the development of asthma, the so-called hygiene hypothesis. However, what determines the progression is being debated. Some believe once you develop childhood asthma you continue to have symptoms. Others believe that there is a rule of third; that following development of asthma, a third goes into quiescence, some recover and others progress.
In 2016, the Nigerian Thoracic Society predicted that about 100 million Nigerians will suffer from asthma in 2025 (in the next five years). According to the organisation, the country has 15 million sufferers from the lung disease out of over 350 million others believed to be suffering from asthma worldwide. What is your take on this?
I am not sure of that prediction of 100 million Nigerians having asthma. This is rather nebulous because the world prevalence of asthma is about 350 million. I think they may have been misquoted. I do not think Nigeria will have one-third of asthma sufferers in the world. Considering the current trend, that may not be possible but there could be increase in asthma prevalence as some of the factors responsible for asthma are still with us as industrialization takes over the rural environment.
What are the newer therapies in the management of asthma?
Severe allergic asthma could sometimes be very difficult to treat, in other words they may not respond to the commonly used asthma medications. In recent times, several new medications, known collectively as ‘biologics,’ have been approved for the treatment of moderate-to-severe asthma. Biologics are unique in that they target a specific antibody, molecule, or cell involved in asthma. Because of this, they are known as ‘precision’ or ‘personalized’ therapy.
A biologic is a medication made from the cells of a living organism, such as bacteria or mice, that is then modified to target specific molecules in humans. For asthma, the targets are antibodies, inflammatory molecules, or cell receptors. By targeting these molecules, biologics work to disrupt the pathways that lead to inflammation that causes asthma symptoms.
Some examples of these drugs include: Omalizumab, which targets allergy antibodies known as IgE and Mepolizumab, reslizumab, and benralizumab which all target pathways that affect eosinophils-which are cells involved in the disease process of asthma. The commonest and most widely used is Omalizumab particularly in Europe, the United States and other regions. These drugs are used as add-on therapies for the treatment of inadequately- controlled severe persistent allergic asthma, despite the use of high dose inhaled steroid and long acting bronchodilators in patients aged 6 years or over.
Among those who used these drugs, severe exacerbations were noticed to decline significantly. Omalizumab is given by underneath the skin injection once every 2-4 weeks based on initial serum IgE level and body weight.
The major drawback of these agents is the prohibitive cost. For example, a vial of 150mg for Omalizumab, cost on the average $1,188. Aside this, these drugs are not readily available in most low- and middle-income countries, like Nigeria. Another disadvantage is that they are mostly injectables and so they have to be administered in the hospital setting under strict monitoring.
Adverse effects such as fever, increase susceptibility to upper respiratory infection, headache, fever, urticaria, injection site induration, injection site itching, pain, and bruising all contributed to making the use of these medications not very desirable. Other forms of therapy include Bronchial Thermoplasty which is an innovative, non-drug procedure developed for the treatment of severe persistent asthma. It involves the use of thermal energy to reduce the increased airway muscle that is associated with airway constriction in asthma patients and also to prevent permanent airway damage, otherwise called airway remodelling.
In recent time, experts have also advocated the use of Tiotropium which is a long-acting antimuscarinic agent. This drug works by relaxing the airways smooth muscles and reducing the increase mucus secretion associated with difficult -to-treat asthma.
At what point exactly do you place an asthma patient on nebulizer?
Nebulizer is a drug delivery device used to administer medication in the form of a mist inhaled into the lungs. Nebulizers break up medical solutions and suspensions into small aerosol droplets that can be directly inhaled from the mouthpiece of the device. They can be oxygen driven thereby giving a dual approach to effectively managing patients with asthma. There are various forms of nebulizers. These include the ultrasonic, jet powered and mesh nebulizers. These devices are basically used in managing acute exacerbations of asthma, chronic obstructive pulmonary disease and in the delivery of certain medications in managing other diseases. The aim of nebulizer therapy is to deliver a therapeutic dose of a desired drug as an aerosol in the form of respirable particles within a short period of time, usually 5–10 minutes.
The medications delivered via nebulizers can also be delivered using an inhaler with a spacer device and this may achieve the same result with a nebulizer. However, nebulizers are useful in acute settings. It is useful when patients do not have spacer devices, if they are too young to cooperate or in the elderly who have poor co-ordination between device actuation and breath, or any condition that makes it difficult to use the inhaler therapy. Research has shown that healthcare providers find it more convenient to administer nebulizers to patients in severe respiratory distress because less education or cooperation is required at such times, it can be oxygen driven, and it is less patient dependent.
How readily available are nebulizers and peak flow meters in our country?
Nebulizers and peak flow meters are now increasingly available in Nigeria compared to what used to happen in the past. OMRON has been actively involved in educating physicians, pharmacists and other healthcare practitioners globally on asthma and the use of peak flow meters, and other asthma devices like nebulizers. I am also aware that OMRON is collaborating with NEW HEIGHTS and they are involved in massive discounted sales of peak flow meters and nebulizers. Also, there are some pharmaceuticals who distribute peak flow meters free to patients. There have also been some charity organizations like Asthma and Chest Care Foundation and Breathe Easy Foundation, UK, who have been actively involved in distributing peak flow meters free of charge to patients. However, this is not enough, we look forward to more participation by philanthropists to make nebulizers, peak flow meters and asthma medications available to the masses. One of my goals as a chest physician is to ensure that every asthmatic on the surface of the earth, especially in developing country, have a peak flow meter available to him or her.
