Related Experiment Video
Updated: Jan 10, 2026
Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index
Published on: January 8, 2020
Applying High-Dimensional Propensity Scores in a Study of Inhaled Corticosteroids and COVID-19 Outcomes
Marleen Bokern1, John Tazare1, Christopher T Rentsch1
1London School of Hygiene and, Tropical Medicine, London, UK.
Background:
In pharmacoepidemiologic studies of COVID-19, there were concerns about bias from residual confounding. We investigated the effects of inhaled corticosteroids (ICS) on COVID-19 outcomes, applying high-dimensional propensity scores (HDPS) to adjust for unmeasured confounding.
Methods:
We selected patients with chronic obstructive pulmonary disease on 01 March 2020 from Clinical Practice Research Datalink (CPRD) Aurum, comparing ICS/LABA/(+/-LAMA) and LABA/LAMA users. ICS effects on the outcomes COVID-19 hospitalisation and death were assessed through IPT-weighted and unweighted Cox regression. HDPS were estimated from primary care observations, prescriptions and hospitalisations. SNOMED-CT codes and dictionary of medicines and devices codes from CPRD Aurum were mapped to International Classification of Disease 10th revision codes and British National Formulary paragraphs, respectively. We estimated propensity scores (PS) combining prespecified and HDPS covariates, selecting the top 100, 250, 500, 750 and 1000 covariates ranked by confounding potential.
Results:
When excluding triple therapy users, conventional PS-weighted estimates showed weak evidence of increased COVID-19 hospitalisation risk among ICS users (HR 1.19 [95% CI: 0.92-1.54]). Results varied slightly based on the number of covariates included in HDPS (HR using 100 HDPS covariates excluding triple therapy 1.01 [95% CI: 0.76-1.33], HR using 250 HDPS covariates excluding triple therapy 1.24 [95% CI: 0.83-1.87]). Conventional PS-weighted models showed weak evidence of a harmful association of ICS with COVID-19 death when excluding triple therapy users (HR 1.24 [95% CI: 0.87-1.75]). HDPS-weighting moved estimates toward the null (HR using 250 HDPS covariates excluding triple therapy 1.08 [95% CI: 0.73-1.59]).
Conclusions:
HDPS may have better controlled confounding for COVID-19 deaths in this case. HDPS results can be sensitive to the number of covariates included, highlighting the importance of sensitivity analyses.
Related Concept Videos
01:26COPD: Management Using Bronchodilators and Corticosteroids
01:25Antiasthma Drugs: Inhaled Corticosteroids and Glucocorticoids
ICS work through a multifaceted mechanism of action. They suppress the inflammatory response caused by the proliferation of TH cells. They also reduce the transcription of the IL-2 gene, which is involved in the...
01:20COPD: Pathogenesis and Clinical Features
The primary cause for the onset of COPD is cigarette smoking and exposure to air pollution. These hazardous factors initiate a chain reaction within the lungs, resulting in chronic inflammation, damage to the airways, and a...
01:26Asthma-II: Pathophysiology and Classification
Additionally, environmental and genetic factors play crucial roles in determining an individual's susceptibility to asthma and the severity of their condition.
Critical processes in asthma pathophysiology include:
01:27Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History
01:20Asthma: Pathogenesis and Management
Asthma is classified as allergic and non-allergic. Allergens such as dust mites, pollen, and pet dander trigger allergic asthma, while factors like cold air, intense emotions, or exercise can induce non-allergic asthma.