Also, mortality in patients with bronchiectasis was significantly more related to respiratory diseases such as chronic obstructive pulmonary disease (COPD) than in those without bronchiectasis.
These findings highlight the urgent need for improved treatment strategies that can extend the lives of people with simultaneous steroid-dependent severe asthma and bronchiectasis, scientists said. Still, future studies are needed to determine whether these associations can be generalized to patients in other countries.
The study, “Bronchiectasis and increased mortality in patients with corticosteroid-dependent severe asthma: a nationwide population study,” was published in the journal Therapeutic Advances in Respiratory Disease.
Asthma is a condition in which the airways narrow and swell, making breathing more difficult. It is estimated that 20%–60% of people with severe asthma need to use a systemic steroid regularly to ease inflammation due to uncontrolled asthma-related symptoms or frequent exacerbations.
Since steroid-dependent asthma is associated with increased mortality, it is important to identify predictive factors of poor outcomes.
Characterized by an irreversible expansion, inflammation, and scarring of the bronchi of the lungs, bronchiectasis often co-occurs with severe asthma and is associated with a greater risk of exacerbations, severe disease, and hospitalization in asthma patients.
However, whether bronchiectasis increases the risk of death in people with severe asthma requiring steroid treatment remains unknown.
To fill this knowledge gap, researchers in South Korea analyzed the survival outcomes and healthcare use of 3,770 adults with steroid-dependent severe asthma: 754 with bronchiectasis and 3,016 without the disorder.
Data were collected from the Korean National Health Insurance Service database from 2005 to 2015. Patients in both groups were matched by age, sex, type of insurance, and co-existing conditions.
The team assessed potential group differences in all-cause mortality, specific causes of death, all-cause hospitalizations, and emergency visits after a mean of seven years’ follow-up.
Results showed that steroid-dependent asthma patients with bronchiectasis had a significantly higher all-cause mortality than those without bronchiectasis (8,429 vs. 6,962 deaths per 100,000 person-years). Person-years is a parameter that sums up the gathered follow-up years of all included patients.
Having bronchiectasis was associated with a significantly lower survival, reflecting a 1.27-times increased risk of death. This higher risk was maintained when analyses were adjusted for potential influencing factors (such as age, sex, insurance type, and the number of used inhalers). In addition, women with steroid-dependent asthma and bronchiectasis showed a higher risk of death than women without bronchiectasis. No such difference was seen in men.
While respiratory diseases were the most common cause of death in both groups — 58.3% in the bronchiectasis group and 42.8% in the non-bronchiectasis group — a significantly greater proportion of people with bronchiectasis died from COPD (37.1% vs. 25.1% of those without the condition).
Patients with bronchiectasis were 1.65-times more likely to die from respiratory diseases, mainly COPD, than those without bronchiectasis.
In addition, the rates of asthma-related and all-cause hospitalization, as well as those of all-cause emergency visits, were significantly higher in steroid-dependent asthma patients with bronchiectasis than in those without the condition.
The researchers hypothesized that bronchiectasis may increase the risk of worse outcome in people with steroid-dependent severe asthma due to an increased frequency of lung infections and a greater decline in lung function.
“Clinicians should manage patients with severe asthma with bronchiectasis more cautiously, as they have higher long-term mortality risk as well as increased exacerbation risk,” the researchers wrote, adding that treatment guidelines for these patients are “urgently needed to improve long-term survival.”
The team said, however, that the available data did not allow analyses adjusted for important risk factors of death, including smoking history, lung function, and lung infection. Detailed clinical data on asthma and bronchiectasis were also not available.
Future studies in other countries and populations are also needed to determine whether these findings may be generalized to the rest of the world, the investigators added.