Calendar time-specific propensity score analysis for observational data: a case study estimating the effectiveness of inhaled long-acting beta-agonist on asthma exacerbations

Dilokthornsakul, Piyemeth, Chaiyakunapruk, Nathorn, Schumock, Glen T. and Lee, Todd A. (2014) Calendar time-specific propensity score analysis for observational data: a case study estimating the effectiveness of inhaled long-acting beta-agonist on asthma exacerbations. Pharmacoepidemiology and Drug Safety, 23 2: 152-164. doi:10.1002/pds.3540


Author Dilokthornsakul, Piyemeth
Chaiyakunapruk, Nathorn
Schumock, Glen T.
Lee, Todd A.
Title Calendar time-specific propensity score analysis for observational data: a case study estimating the effectiveness of inhaled long-acting beta-agonist on asthma exacerbations
Journal name Pharmacoepidemiology and Drug Safety   Check publisher's open access policy
ISSN 1053-8569
1099-1557
Publication date 2014-02
Year available 2013
Sub-type Article (original research)
DOI 10.1002/pds.3540
Open Access Status
Volume 23
Issue 2
Start page 152
End page 164
Total pages 13
Place of publication Chichester, West Sussex, United Kingdom
Publisher John Wiley & Sons
Collection year 2014
Language eng
Formatted abstract
Purpose
Propensity scores (PS) are frequently used in observational studies. PS are usually estimated over the entire study period without consideration of the effect of changing patterns of the included variables over time. This study sought to compare PS estimated using the entire study period (conventional PS) and PS estimated for specific periods (calendar time-specific PS (CTS-PS)), and to determine whether there are differences in estimated treatment effects using these approaches.

Methods
We conducted a claims data analysis. Asthmatic patients who received an asthma controller during 1997–2008 were included. Exposed patients were those who received an inhaled long-acting beta-2 agonist. Conventional PS used the entire period to estimate a PS for individuals. CTS-PS approach divided the study period into 1-year periods and estimated PS separately for each period. Each individual had two PS. Both PS approaches were used to estimate adjusted hazard ratio (HR) for asthma exacerbations using Cox proportional hazard models.

Results
A total of 288,518 patients with an average age of 11.9 ± 5.8 years were included. The difference between conventional PS and CTS-PS in each period ranged from −0.213 to 0.098. The adjusted HR of conventional PS-matched cohort was 1.20 (95%CI: 1.18–1.22), whereas the estimate for the CTS-PS-matched cohort was 1.24 (95%CI: 1.23–1.37).

Conclusion

Focusing on a specific year, there was a difference between conventional PS estimated versus CTS-PS for that year. However, there was minimal effect of CTS-PS on the observed treatment effects compared with conventional PS approach. 
Keyword Asthma
Calendar time-specific propensity score
Conventional propensity score
Inhaled long-acting beta agonists
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Public Health Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 0 times in Thomson Reuters Web of Science Article
Scopus Citation Count Cited 3 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 18 Feb 2014, 00:23:30 EST by System User on behalf of School of Public Health