Can high altitude climate therapy (HACT) result in long term benefits for adults with severe asthma?
How much do you know about asthma? Have you ever considered that the air we breath every day is often filled with environmental triggers that worsen asthma symptoms making it more difficult for asthmatics to breath? Did you realize that at elevation many of those environmental triggers such as air pollution and pollen are gone? The rumors are true, mountain air really is better and residents at altitude are truly lucky to be breathing in fresh, clean, crisp mountain air on a daily basis.
Based on data collected by The Global Initiative for Asthma (GINA), as of 2004 it was estimated that 300 million people of all ages worldwide suffer from asthma. That number is projected to increase to 400 million by 2025! In 2010, the CDC documented that 1.8 million people in the US alone visited the emergency department for asthma related care and of that number at least one third of them had to be hospitalized for severe symptoms.
Asthma is characterized by: 1) Chronic airway inflammation, 2) intermittent and reversible airway obstruction, and 3) bronchial hyper-responsiveness (the tendency of airways to narrow in response to a variety of triggers in the air that have little effect on people without any respiratory disease). Patients with asthma often complain of intermittent cough, shortness of breath (or difficulty breathing), and wheezing. This classic presentation is often worsened by triggers such as allergens, pollutants, tobacco, cockroaches, pollen, mold, stress, upper respiratory infections, weather and/or exercise. Symptoms are alleviated with bronchodilator medications, which act to open the airways making breathing easier.
Asthma is conventionally treated in a step-wise fashion, meaning that treatment escalates with increasing severity of symptoms. Patients who suffer from severe asthma on a daily and nightly basis are often on multiple medications in an attempt to control their symptoms. These usually include an inhaled corticosteroid medication, a long-acting beta-2 agonist. Some start oral steroids and some even require biologic or immune modulating agents. Patients that fall into this category often suffer from a decreased quality of life, multiple doctor or emergency room visits and have difficulty controlling their symptoms on a regular basis.
Recently, researchers have been investigating different avenues to provide relief for patients suffering from severe asthma symptoms. Studies published on high altitude climate therapy (HACT) are showing positive outcomes for adults with severe asthma that are refractory to conventional treatment.
An article published in 2018 in The European Journal of Allergy and Clinical Immunology conducted a study to determine if HACT resulted in long term benefits for asthmatics even after returning to sea level. Patients included in this study had to fall into the category of an adult with severe uncontrolled asthma symptoms despite conventional treatment methods. These patients were enrolled in a 12 week multi-disciplinary treatment program with environmental trigger avoidance in an alpine climate at an altitude greater than 1500 m (4921.26 ft). After the conclusion of the program, patients were followed for one year with repeat evaluations every 3 months to assess the long term effects of this therapy on their asthma symptoms.
This is the first study to show a decrease in exacerbations and improvement in asthma control up to 12 months!! This was measured in the number of asthma exacerbations, hospitalizations, and oral corticosteroid use before and after HACT treatment. The study showed a decrease in all three categories, which correlates to a positive outcome following this treatment.
While “trigger avoidance” has always been an important aspect of the conventional asthma treatment regimen, it is amazing to see how patients benefit when this is carried out effectively. It is hypothesized that allergens work to continually stimulate and maintain the airway inflammation in asthmatics. When these triggers are removed for a sufficient amount of time, the bronchioles have a chance to recover and decrease the process of ongoing inflammation.
Another proposed mechanism by which this treatment is effective is the decrease in air viscosity at altitude, which benefits the patient by decreasing the thickness of airway mucosa and may even reverse airway modeling. This makes breathing easier for patients and acts to decrease asthma symptoms.
So who can benefit from this treatment? Are all asthmatics created equally?
Scientists and clinicians alike have identified three different groups of asthma patients: 1) severe atopic asthma, 2) persistent eosinophilic asthma, and 3) asthma associated with morbid obesity. While classically these different patient populations respond differently to asthma treatments, it has been found in another study, “Predictors of benefit from high altitude climate therapy,” that HACT improves the quality of life and respiratory function in all patients suffering from severe asthma symptoms. This study sought to investigate if different factors such as age, blood eosinophils (a type of white blood cell), and degree of asthma control prior to admission could predict how much a patient would benefit from high-altitude climate therapy. While this study is making steps in the right direction, it was determined that further patient characterization is required to clearly identify which patients will benefit the most from HACT.
Finally, in a systematic review and meta-analysis on HACT, it was determined that patients experience a statistically significant improvement in lung function following this treatment modality. This review wanted to analyze the quality of research studies completed so far on this topic and also proposed some limitations of the publications so far.
Some things to consider that are still being evaluated include: What is the optimal altitude and duration of treatment in order to see the most benefit? Which patients will experience the most improvement from this treatment? How does this treatment method compare financially with others considering that it is a resource-intensive intervention?
Overall, research on HACT is making exciting headway! So far we have learned that adults with severe asthma can benefit from alpine treatment in some way regardless of phenotype. In addition, many patients experienced lasting improvement for up to 12 months. Be on the lookout as more research is published on this topic. As always, if you are patient suffering from asthma, check in with your primary care provider prior to making a trip to altitude to ensure your asthma is well controlled before arrival. While HACT has been shown to decrease asthma symptoms long term, arriving at altitude unprepared with uncontrolled symptoms could put an asthmatic at higher risk for high altitude sickness. As discussed at the beginning of the article, cold air can be a trigger for asthmatics as well and with that in mind it would be best to visit the mountains during the summer months! Lastly, always be prepared and carry your rescue inhaler with you, especially when traveling to altitude.
Sarah Gordon is currently a Physician Assistant Student at Midwestern University located in Glendale, Arizona. She plans to complete a one year fellowship at Mayo Clinic in otolaryngology/ head and neck surgery after graduation. Throughout her clinical year she has had the opportunity to travel to Denver and Frisco, Colorado, along with completing rotations located throughout the greater Phoenix area in Arizona. When she is not studying, she enjoys cooking new recipes, spending time with friends and staying active through fitness and outdoor adventures.
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