A recent study in International Ophthalmology explored the relationship between childhood asthma and the risk for developing cataracts in adulthood, particularly with corticosteroid treatment.
Give me some background first.
Asthma is a chronic respiratory condition characterized by airway inflammation, obstruction, and symptoms such as wheezing and shortness of breath.
Inhaled corticosteroids (ICS) in inhalers are cornerstones in asthma management, reducing inflammation and improving symptoms.
- However: Long-term use of corticosteroids is associated with a variety of adverse effects, including cataract formation.
Now, talk about the study.
Researchers in Denmark conducted a register-based study using the National Patient Registry of Denmark to explore whether ICS use during childhood increases cataract risk later in life.
Who was included in the study?
Patients with:
- A history of childhood asthma
- Previous residence at the Kongsberg asthma care facility in Norway
In total, 1,394 patients were enrolled and matched 1:1 with control participants by age (defined by year of birth) and sex.
- The control group did not have history of any obstructive respiratory disease (ie. asthma or chronic obstructive pulmonary disease [COPD]) or current or previous prescriptions for medications for such diseases.
And how was the data analyzed?
Researchers retrospectively studied cataract incidence, ICS dose, and ICS treatment duration between the years 2006-2018.
Conditional logistic regression was used to determine:
- Relationships between risk of cataract formation and each of the ICS variables (dose and treatment duration)
- Cataract formation risk for the childhood asthma patients versus the control group, reported as odds ratios (OR) with 95% confidence intervals
Now to the findings.
Researchers determined:
- The childhood asthma cohort was 1.4x as likely to develop cataracts as the control group, who had no history of obstructive pulmonary disease
- Within the childhood asthma cohort, patients who received ICS treatment for asthma had a significantly higher risk of developing cataracts than the control group
In contrast…
- There was no significant increase in cataract development risk for patients who did not receive ICS treatment for asthma compared to the control group.
Take note: Confounding factors such as age, sex, socioeconomic status, BMI, diabetes, and corticosteroid use via other routes (ie. topical, oral, etc.) were accounted for.
Tell me more.
ICS treatment duration:
Among those who developed cataracts and had received ICS treatment, 63.2% had been treated for ICS for over 10 years.
Conversely, 51.9% of patients who received ICS treatment but did not develop cataracts had been treated for less than 10 years.
OR for cataract formation increased with ICS duration:
• 5–10 years: OR = 2.2
• 10+ years: OR = 2.5
ICS dose: Higher ICS doses were also associated with increased risk:
• 200–400 mcg/day: OR = 1.1
• 400–800 mcg/day: OR = 5.5
(compared to <200 mcg/day)
Limitations?
A few were called out:
- Since this study focused on Danish patients up to age 63, it is unclear whether the results can be generalized to other demographics and to ages over 63
- There may be a physiological basis that directly links asthma to cataract formation, which would be a confounding variable in this study
- Asthma severity was not accounted for either
- Different childhood respiratory conditions may present in similar ways—thus, it is possible that some patients may have been misdiagnosed with asthma in childhood
- This may weaken the relationship found between asthma and cataract formation
- Data on smoking status was not available for this study
- Smoking may pose a confounding variable as smoking has been shown to be a risk factor for cataracts
- Variations in reporting and coding practices between private and hospital settings may have led to underreporting of cataract prevalence
Take home.
There appears to be a dose-dependent and duration-dependent relationship between ICS treatment for childhood asthma and cataract formation in adulthood.
- Thus, ICS dosing and duration considerations should be taken into account when treating asthma, as well as regular ophthalmologic monitoring in adults with a history of asthma and ICS usage.
Further research is needed to clarify whether asthma itself contributes to cataract development.