Low-Dose ICS for Mild Asthma Prevents Small Drop in FEV1 Seen in High Altitudes

In those with mild, seasonal asthma not using ICS during winter, exercise and cold air at high altitudes leads to a small loss of FEV1.

Low-dose inhaled corticosteroid (ICS) treatment in individuals with mild, seasonal asthma prevents a decrease in pulmonary function in response to high altitude (HA) environmental factors, according to study findings published in the World Allergy Organization Journal.

Researchers sought to evaluate the effect of HA climate on forced expiratory volume in 1 second (FEV1) among individuals using seasonal inhaled corticosteroids (ICS) who had well-controlled allergic asthma.

The researchers conducted a longitudinal controlled study involving 21 individuals divided into 2 cohorts: an asthma cohort of 10 individuals (5 female; mean age, 41 years) with mild seasonal well-controlled bronchial asthma taking low-dose ICS treatment during pollen season (and no ICS treatment off season); and a control cohort of 11 healthy individuals (7 female; mean age, 40 years) without asthma, who were well matched to the asthma group according to health, physical activity, body mass index, age, and sex/gender.

Participant responses to HA factors (including cold temperature and physical exertion) were measured and analyzed at about 2600 meters above sea level in January. For the asthma group, responses were measured twice; once when participants did not take ICS, and then at another time point when these participants did receive ICS treatment.  These HA measurements were then compared with low altitude (LA; ie, 500 meters above sea level) FEV1 measurements taken from participants in both groups. In the asthma group, the measurements were taken in March, at the start of pollen season, when individuals in the asthma cohort were using ICS treatment.

In comparing post-exercise measurements taken at HA vs LA, the researchers found that individuals in the asthma group, when not using ICS, had an FEV1 that was 230 mL higher (P <.05) than that of individuals in the control group. Notably, FEV1 was not heightened among those in the asthma group when these individuals received ICS treatment. The study authors commented that while the FEV1 loss of 230 mL was statistically significant, it was nevertheless minimal and of limited clinical relevance.

As the drop in FEV1 occurring as a result of HA triggers is small, a preventive ICS treatment before a planned HA stay does not seem necessary for most patients with such mild disease.

The researchers further found a reduced methacholine response at HA vs LA, and no differences between the control and asthma groups. The effect of hypoxia on bronchodilation was analyzed by assessing participants’ response to salbutamol after methacholine was measured. The investigators found no significant differences between the HA and LA measurement for the asthma and control groups.

Study limitations include the underpowered sample size; selection bias (ie, the inclusion of only individuals with well-controlled seasonal disease); the inability to control variability in HA and LA conditions that could potentially affect measurements; and the generally low altitude of the HA measurements.

Researchers concluded that individuals with mild, seasonal asthma who are not using ICS treatment during winter experience a small but significant loss of FEV1 in high vs low altitudes from the combination of exercise and cold air exposure, and that this slight loss in pulmonary function could be avoided through ICS treatment. However, added study authors, “As the drop in FEV1 occurring as a result of HA triggers is small, a preventive ICS treatment before a planned HA stay does not seem necessary for most patients with such mild disease.


Mertsch P, Götschke J, Walter J, et al. Response to high-altitude triggers in seasonal asthmatics on and off inhaled corticosteroid treatment. World Allergy Organ J. September 24, 2022;15(10):100698. doi:10.1016/j.waojou.2022.100698